Speaking: From Intention to Articulation

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Speaking Willem J. M. Levelt

RELATED TOPICS Linguistics

"Required reading for anyone w orking in the field." -- Joseph Paul Sternberger, Contemporary Psychology

Aug 1993 ISBN 0262620898

In Speaking, Willem "Pim" Levelt, Director of the Max-Planck-Institut für Psycholinguistik, accomplishes the formidable task of covering the entire process of speech production, from constraints on conversational appropriateness to articulation and self-monitoring of speech. Speaking is unique in its balanced coverage of all major aspects of the production of speech, in the completeness of its treatment of the entire speech process, and in its strategy of exemplifying rather than formalizing theoretical issues.

584 pp. "[Levelt] synthesizes the state of the art w ith remarkable breadth, depth, and clarity. In 500 pages of highly readable text and forty pages of bibliography, he integrates, as no one has done previously, many lines of research that have often been pursued in ignorance of one another.... An outstandingly instructive book." -- Dan Sperber, Times Literary Supplement "A w ork of massive scholarship and authority." -- Brian Butterw orth, Times Higher Education Supplement

Table of Contents Preface Acknow ledgments Author's Notes 1 The Speaker as Information Processor 2 The Speaker as Interlocutor 3 The Structure of Messages 4 The Generation of Messages 5 Surface Structure 6 Lexical Entries and Accessing Lemmas 7 The Generation of Surface Structure 8 Phonetic Plans for Words and Connected Speech 9 Generating Phonetic Plans for Words 10 Generating Phonetic Plans for Connected Speech 11 Articulating 12 Self-Monitoring and Self-Repair Appendix: Symbols From the International Phonetic Alphabet, With Examples Bibliography Author Index Subject Index

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) 1- 4. North-Hollanri Lingua92 ( 1994

Preface For many years, the topic of lexical acquisition was a stepchild in linguistic inquiry . While" the acquisition of syntax was acknowledged to be organized according to a set of deep and highly structured innate principles, word meanings were assumed to be acquired by a simple and particularistic associativeprocedure that mapped perceptual experienceonto phonetic entities . We believe this stance was anomalous from the start, as had been pointed out eloquently by Plato and, in modem times, by Quine. Not all words are perceptually based; even those that are map quite abstractly from ' ' perceptual categories; and neither perception nor learning is simple . During the past decade, it has becomeclear from linguistic inquiry that the lexicon is more highly structured than heretofore thopght ; moreover, that much of grammar turns on critical - and universal - links between syntactic and lexical-semanticphenomena. Hence the present volume. The papers grew out of a workshop held at the University of Pennsylvania. Its aim was to bring together psychologists, computer scientists, and linguists whosejoint concern was the lexicon and its acquisition; these researchershave typically worked quite separately and on problems thought to be disparate. The volume is organized in six sections: 1. Nature of the mental lexicon.. The two essaysthat open the collection are from linguists gleaning general perspectiveson lexical learning from the linguistic facts themselves. The first , by Edwin Williams , arguesfrom the real complexity and idiosyncratic nature of the mental lexicon (including lexical phrases) that innate linguistic and categorization principles are not enough, that real children require a learning theory more sophisticated than usually has been supposed. A detailed analysis of English causativealternation verbs by Levin and Hovav eloquently supports Williams on the complexity of lexical structure. 2. Discovering the word units.. To acquire a vocabulary, the learner requires some proceduresfor segmentingthe continuously varying sound wave into word -sizedpieces. Cutler discusses this problem, presentingevidencethat a bias toward rhythmic alternation servesas a powerful bootstrap for infants (and adults , whatever their specific language background) solving this problem. Kelly and Martin then show that , armed with such blases, learners B.V. All riahtsreserved 0024 - 3841 /94/ 507.00 ~ 1994- ElsevierScience SSDI 0024- 3841( 93) EO036- 7

2

Preface

exploit multiple probabilistic cuesto discover the word units: domain-general learning procedurescan be used to discover many domain-specificfacts about language. ' 3. Categorizing the world: The word meaning culled from children s interaction with the world ultimately depends on how they represent their ' observations. A first question is whether children s mental representations (categories, and the theories that bind them) are the same, no matter the age ' of the learner. In her article, Carey makes a strong casefor a ' discontinuity theory, in which the very basis of inference from observation onto meaningidentification changesover developmental time. Keil , in contrast, argues that the mentalities of children and adults hardly differ. For both , his view is that concept and word acquisition involves both the discovery of multiple probabilistic surface factors (reminiscent of Kelly and Martin ) and some theorydriven generalizations. 4. Categories, words, and language: A further set of articles again documents ' how the child usesthe evidenceof observation to decide on a word s meaning. But theseemphasizethe role ~f linguistic principles as an additional determining factor. Thus Markman points out that the learner is biased ' toward a ' whole object assumption - a new word probably namesthe whole animal rather than one of its parts or properties. But then how could a child learn ' nose' or ' white' ? She provides evidence for a linguistic principle ' ' ( mutual exclusivity ) that leads children to avoid two labels for the same object. Waxman shows experimentally that such blases, even in the toddler , are specifically related to the characteristic semantic properties typical of lexical classes- nouns name objects but adjectives name properties. Landau ' ' ' ' shows how the separation and respectivestructures of the what and where systems(as documentedby neuropsychologists) are related, in learning, to the child ' s acquisition of object namesvs. place expressions. All thesearticles are neutral concerning the direction of the causal links here: the extent to which the perceptual- conceptual facts determine lexical class assignment, or the other way round. Bloom takes a stronger view in discussingthe acquisition of nominal subtypes (count vs. mass noun, noun phrase) : He holds that very early in life children consider syntactic form classas relevant to determining a novel word ' s meaning. 5. The caseof verbs: The papers mentioned thus far make a strong case that the form -meaning linkages that typify language design are exploited by children acquiring the vocabulary of their native tongue. Grimshaw ( 1981) and Pinker ( 1984) emphasized, on the basis of these linkages, that children could derive lexical class assignment from experience-based learning of the

Preface

word ' s meaning; Pinker showed further that such a procedure would be ' marvelously useful for the construction of phrase structure ( semantic boots' . Landau and Gleitman 1985 ( ) emphasized that learning might trapping ) sometimes, even usually, be the other way round ; specifically, that syntactic structure plays a necessary role in narrowing the search space for verb ' ' meanings ( syntactic bootstrapping ) . The three articles in this section hotly debate how the semantics-syntax links (specifically, the relation betweenverb argument structures and subcategorization structures) are implicated in the learning processfor verbs. Fisher, Hall , Rakowitz , and Gleitman emphasize the role of syntax in narrowing the range of interpretations made available by experience; Pinker argues that logically the child must work from experience to determine the syntax in the first place; and Grimshaw stalwartly proposes a reconciliation of these two views. 6. Proceduresfor verb learning: The positions just described, even if correct, can suggestonly some boundary conditions on a learning theory for verbs. Fisher et al., asjust described, assertthat some rudiments of syntax are necessaryfor learning the verb meanings. But as Pinker points out , the question then would be: How did the child acquire the syntax if not by exploiting the word meanings themselves? Brent, in the best tradition of computer science, offers a discovery procedure for verb subcategorization that usesstring-local surface cues only , and does surprisingly well. The final article in the volume, from Steedman, was designedas a specific commentary on Brent' s work . But this short article is much more general than that. It strikes a number of sane cautionary notes about current theories of verb learning, of which the most important is that real acquisition is bound to be a messybusiness, with syntactic, semantic, and prosodic cues recruited by the child more or less catch-as-catch-can. Steedmanalso points out , in what we find an appropriately laudatory comment, that it is only in the presenceof ' explicit computational models such as Brent s that the bootstrapping theories can ever be developedand seriously evaluated. It is the hope of the editors that this compendium of topics and views on lexical learning will be of particular use to the linguists who constitute the Lingua audience, in two ways. First , we suppose it will be useful to see the kinds of methodological and substantive contributions that scientific psychology can make to the question of languagelearning - and henceto the theory of language. Second- as we have emphasizedearlier - becausesyntactic and lexical structure are so closely entwined, we expect that the various articles will be informative as to how theselinkages enter into the learning procedure for vocabulary.

Preface

We thank Lingua for the opportunity to air theseworks in this Special Issue, and we particularlythank the LinguaChief Editor, Teun Hoekstra, for this continuingaid and supportof this project. We thank also the National ScienceFoundation which, through an STC grant to the University of Institutefor Researchin Cognitivescience Pennsylvania , madethe Workshop . In that regard, we areespeciallygratefulto the staffof IRCS (Trisha possible Yanuzziand Chris Sandy) and to Carol Miller, Kimberly Cassidy , and Sally Davis (graduatestudentsin the Departmentof Psychology who ran the ) with verve and considerable , efficiency Workshop , good humor. Finally, we thank Stevenand Marcia Roth for a grant to Lila Gleitmanwhichaidedus in the preparationof the Volume.

, June1993 Philadelphia

Lila Gleitman Barbara Landau

Acknowledgments

This book emergedin the stimulating circle of the Max -Planck-lnstitut fiir ' Psycholinguistik and Nijmegen University . Numerous colleagues can t give up educating me in matters linguistic and psycholinguistic, and I would be at a losswithout them. Also , many distinguishedvisitors from all over the world have given me help and advice. I am sincerelygrateful to all of them. Some, from within and without this circle, have taken the effort to read drafts of chapters and to formulate comments, either orally or in writing . Before mentioning them, I must say that each of theseefforts has deeply touched me. Time and again I experiencedit asa great privilege to be taken so seriously and with so much friendship. In alphabetical order, these angelswere Manfred Bierwisch, Melissa Bowerman, Herbert Clark , Anne Cutler , Jane Edwards, Lyn Frazier, Merrill Garrett , Gerard Kempen, Wolfgang Klein , Aditi Lahiri , and John Marshall . I would also like to thank Gerard van Galen, who gave me a specialtutorial on psychomotor theory. Though I typed the manuscript myself with two index fingers on a terminal , finishing toucheshave beenmade by Uschi de Pagter and Edith Sjoerdsma, especiallyin completing the bibliography . Our librarian , Karin Kastens, also helped me on countlessoccasions. Many thanks to all three of them. The graphic work was done by Wil Maas during three months of ideal cooperation.

NiJmegen . February 29, 1988

Author ' s Notes

On Pronominalization in to the present chaos of person pronominalization male whether : conventions , Speakers, English by adhering to the following or . Hearers female , or generic , will receive masculine pronominalization addressees will be treated as female . When there are two or more interlocutors (i .e., speakers/ hearers) , the first one will be male , the second one female , and so on in alternation . General use of these conventions in psycholinguistics will , given the bias for language - comprehension research,

I will contribute

make most person reference female . On Tr ~

ription

I will follow the transcription conventions of the International Phonetic Alphabet . The phonetic symbols used are listed in the appendix .

) 7- 34. North-Holland Lingua92 ( 1994

Remarks on lexical knowledge EdwinWilliams CognitiveScienceLaboratory, Princeton University, 221 NassauStreet, Princeton, NJ08540, USA ' ' The abstractnessof lexical knowledge, and its independencefrom the words of a language, are is the the lexicon that idioms demonstrate . Abstract repository not only generally underestimated of fixed expressions, but of abstract language-particular phrase- and word-patterns as well. Paradigmsare language-particular patternings dimensionedand structured in languageparticular two abstract of these burden . The of with learning languageparticular patterns syncretism ways, but learned features of lexical knowledge falls ouside of what current thinking about language learning would allow.

1. Introduction I will survey two aspects of lexical knowledge which I feel pose special problems for learning. In both casesthe remarks will tend to emphasizethe extensivenessabstractness , and at the sametime the language-particularity of lexical knowledge, and will consequentlymagnify the learning problem. One conclusion that could be drawn from these observations is that intricate structures can be learned, and this learning is not adequately modelled by . either parameter setting or list learning. I t is useful to distinguish two notions of lexicon, one Bloomfieldian and the other grammatical. The Bloomfieldian lexicon is the repository of all of a ' is the linguist' s theory of languages idiosyncracies. The grammatical 'lexicon ' the category of linguistic object we call a word . These are quite different conceptions, but have come to be identified in modern times. The result is a picture of grammar in which we have a clean streamlined syntax, where syntax is the theory of phrase, and a notion of word that entails that words are idiosyncratic and irregular at heart, with partial regularities expressedas ' ' redundancy rules whose name implies low level generalizationswhere exception is the rule. I think that this picture is wrong. A more correct picture is I think given in Disciullo and Williams ( 1986) . In that view, both the word formation and the ScienceB.V. All rightsreserved -3841 0024 /94/$07.00~ 1994- Elsevier -G SSDI0024-3841(93)EOOS9

E. Williams / Remarkson lexical knowledge

' ' syntactic system are clean streamlined systems, independent of the lexicon. The lexicon is the repository of forms about which something specialmust be learned. This certainly includes, for example, all the monomorphemic words, but it also includes composed units of both syntax and word formation , composed units whose properties do not all follow from the rules which compose them. This would include a great deal of words, but also a great deal of phrases. In fact, I now think there are more lexical phrasesthan there are lexical words, but this re~ ains a speculation. In addition , I think that lexical knowledge includes knowledge of complex abstract.structures that cannot be arrived at through parameter setting, and which must be learned from the data in a strong sense. I will discusstwo of these: ' abstract idioms' in section 2, and paradigms in section 3. If my view of theseis correct, the rich structure each exhibits results not from a rich innate predefined linguistic structure, but rather from a richly structured learning strategy. If nothing else, then, the remarks that follow draw attention to the learning problems that might arise if first , more ~f linguistic knowledge is lexical than has been thought, and second, if acquired lexical knowledge is more abstract and structured in language-particular ways than has been thought . I think that the sort of structure that is found in each case reveals the hand of the learning strategy.

2. Idioms

The phrasesin the lexicon are called ' idioms' . We generally think of idioms as ' frozen' expressions. I will use the term idiom to refer to any defined unit whose definition does not predict all of its properties. This will include the phrase kick the bucket, a phrase, whose idiomatic meaning is die, but also transmission, which unpredictably means ' such and such car part ' . We don' t think of transmissionas an idiom , but it will be useful and I believecorrect to include it . It has been commonly assumedthat idioms are well-formed structures, but I think lately this view has been questioned. To say that an idiom is well formed is to say simply that it conforms to the rules of formation for the type that it is. Of course, the idiom does not conform to all of the rules, else it would not be an idiom . What rules do idioms obey? It is useful to consider the rules of ' form ' apart from the rules of interpretation . We find idioms violating both types of rules.

E. Williams I Remarks on lexical knowledge

The idioms that do not obey the rules of interpretation are deviant in meaning. The rules of argument structure are not obeyed in some cases, and in others, the rules of referenceare not obeyed. We might refer to both these ' ' types of idioms as semantic idioms. It is perhaps misleading for me to say that there are idioms which do not obey the rules of form , for it is an overwhelming fact that idioms obey the basic rules of fonn it) a language. For example, all idioms in English obey the ' head-initial ' setting of the head position parameter. On the other hand, there are unpredictable, language-particular exploitations of the formal possibilities ' in a language; we might call theseidioms ' formal idioms. A widely shared set of assumptionsabout idioms is the following : ( 1) usual assumptions: idioms are listed idioms are well-formed phrases idioms have empty parts : The cat has Xs tongue relation of idioms to syntax: insert the idiom , then fill in the parts ' So, for example, The cat has got X s tongue is an idiomatic phrase, fully consistent with the laws of English syntax, which is inserted in a phrase marker for an S position ; further substitution of a referential NP for the position of X will yield an English sentence. These assumptions, though common, lead to some surprising conclusions, or at least some surprising conclusions, or at least some surprising questions. . In particular , they lead to the view that a great deal of what we have called ' ' ' rule' in syntax might really be idiom . To give an example, consider the fact that embeddedquestions in English must begin with a WH word. It is well known that this is not to be describedby making WH movement obligatory in English. What kind of information is it then that [ Wh-phraseS ] is a (potential) embeddedquestion in English? It COULD be that this form is an idiom : ' ' (2) [[ Wh-phraseS ]. , : embeddedquestion Under this conception, (2) could be listed in the lexicon, awaiting insertion into some embedded S position, where it is an embedded question (as the slogan after the colon above indicates) . Further substitution of some wh

E. Williams I Remarkson lexical knowledge

phrase for the wh-phrase position in (2) and of an S for the S position in (2) will complete the sentence, exactly parallel to The cat has got X 's tongue. One does not ordinarily think of this as idiomatic information , even though it is languageparticular ; rather, one thinks of this feature of English as one of the ' parametric' possibilities. (2) is not the ordinary way to encode this information . Example (2) may seem sufficiently different from The cat has got your tongue that it would never be misidentified as an idiom in the same sense. However, I intend to supply enough examplesof casesintermediate between the two ' that I cannot see how it cannot be questioned whether (2) is the correct description or not. 2.1. Idioms are instances of we//- formed structures

The view that I am presentingherewould have large numbersof objects of a sometimesquite abstract character stored in the idiom lexicon of language. This view might then be seenas convergi.ng with severalrecent proposals that . there are 'constructions' in language, a backlash against the principles and parameters model. There is, though, a fundamental difference between the proposal here and those proposals - specifically, I hold that idioms are well formed, and that the rules of well-formednessare simple ' parameterized' rules. 2.1.1. Filmore's examples For example: C. Filmore (p.c.) has sugg~sted to me that while most prepositions in English are prepositions , some are not , and consequentlythe notion that there is a uniform head position in English is not correct ; the most ,:>ne can say is that there are a number of constructions in which the head is leftmost, and some others in which it is not. His candidates for postposition in English are notwithstandingand ago: (3a) John notwithstanding, we will go there tomorrow . (3b) John left 3 days ago. I believe that neither of these is a preposition, and that the notion that English is head initial can be maintained in a strong form . Notwithstandingcan be assimilated to the following constructions:

(4a) John aside, ... That noted, ...

on.lexical E. Williams / Remarks knowledge which are clearly small clauseconstructionsof somekind. The difference and asideis that asidecan appearin other small betweennotwithstanding whereas clauseconstructions , notwithstandingis restrictedto the context indicated: (Sa) put that aside, * notwithstanding . (Sb) We may ~xpress this restriction on notwithstanding by not listing it in the ' ' lexicon on its own , but only as a part of the following idiom :

' ' ]sc S]s: evenwith NP, S (6) [[NP notwithstanding Importantly, (6) is an instanceof a structurewhich is well fonnedin English , namelythe structureof (4) : independently

(7) rNP - AP]- S > >

' ' [ NPnotwithstandingS: even

' I will usethe doublecarat sign' > > ' to mean' hasa well-formedinstance. I think ago as well has a better analysisthan the postpositionalone. Consider: (8a) long (8b) 5 minutes (8c) a few days

ago in the past before the party

It appears that time prepositions in general can take some sort of extent specification; however, this specification in general precedesthe time preposition , as we might expect specifiers to. (8c, d) shows clearly that the extent specification is not a part of the complement structure, as the prepositions in and before have complements to their right . Now , ago differs from these in two ways. First , it cannot have a complement to the right . This however shows nothing except that ago is intransitive. Secondly, in the caseof ago, the extent specification is obligatory . Here, if we think that extent specification is ordinarily outside of the subcategorizational reach of a head, we might appeal to an idiom to capture this exceptional feature of ago:

E. Williams/ Remarkson lexicalknowledge

' I complements right , specs left ' > > assign [(Extent-spec) P (NP)]pp> > [Extent-specago]pp Here, the idiom is a well-formed subinstanceof prepositional phrase, which itself is a ' subinstance' of all the structures that fall under the parametric specializationsof English. In sum then, although the notion of idiom we are employing is quite general, it is at the same time quite restrictive, in that all idioms conform to more abstract (though perhaps parameterizedlanguageparticular) principles. 2.1.2. What rules.do idioms obey? Idioms basically obey the (rules determining the) phrase structure of the language, but not the rules of reference; so for example, kick the bucket is a well-formed VP, but no referenceto any bucket is made. These two observations set someouter bounds. I think a more interestingprobe is theta structure, where it turns out in fact that idioms diff ~r in the extent of their conformity . . It is well known that idioms differ in their syntactic ' transparency' - ' kick the bucket' does not passivize, whereas' cross that bridge when we come to it ' does. Fiengo ( 1974) connected this difference to a further difference, namely, a difference in whether the object can be quantified : ( l Oa) * They kicked the buckets (as an idiom ) ( lOb) We will cross those bridges when we get to them. In (b), ' bridges' refers to ' problems' , and (b) says that we are talking about more than one problem. In (a) on the other hand, it is impossible to refer to more than one death. Is this an arbitrary difference? I do not think so; I think it follows from the fact that the meaning of ' kick the bucket' is intransitive. This intransitivity of meaning meansthat there can not be a correspondencebetweenthe syntactic and semanticargument structures, sincesyntax is transitive here. In (b) on the other hand, the verb cross can be assigneda transitive theta structure, and one of its theta roles can be assignedto bridges. So what is wrong with the meaning of (b) is simply the reference, not the theta structure: cross refers to solve and bridges refers. to problems. But in (a), it is not just reference, but . theta structure itself, which is idiosyncratic. If this is so, then (b) has a transitive theta structure, and its passivizability is no surprise, if passiveis an operation on theta structures, as I believe it is.

E. Wi/Iiams / Remarkson lexical knowledge

And the fact (a) is not passivizableis no surprise either, sincethere is no theta relation betweenthe direct object and the rest of the sentence. If this account is correct, then theta structure is not necessarilyrespectedin idioms, though it may be. A child learning an idiom will aggressivelyassignit as much structure as possible according to its rules. If it can assign it a semanticargument structure basedon its syntactic argument structure, it will , but if not , then the idiom will lack argument structure.

2.2. Abstractidioms 2.2.1. Idioms with instances If we begin with the idea that an idiom is a phrase, and that it can contain empty parts, then we immediately face the question, how empty can an idiom be? Can it , for example, be mostly empty? The question arisessharply for an example like the English noun pants. This noun, as is well known , is an ' ' arbitrary plural ; a shirt , for example, of the same genus topologically (at least when the fly of the pants is unzipped) is singular. This is a trivial piece of .idiomatic , that is unpredictable, information about this noun, that it must be plural. Strikingly , though, this is not true of this noun alone, but in fact of every word that has the meaning that pants has: something worn on the legs in such and such a way : ( 11) pants jeans shorts cutoffs culottes bermudas ... New, made-up terms for lower trunk wear must conform as well. One exception, bathing -suit , is an exception only in that it does not specifically refer to lower - trunk wear, but rather means whatever one wears to bathe in ; it is an accidental fact of current fashion that this refers to lower -trunk wear. Now , what sort of information is this? It is information about a general restriction on form that follows from meaning; specifically, if a noun is going to have such and such a meaning, then it must be plural ;

' ' ( 12) Ns +- : lower trunk wear I .have drawn the arrow from right to left to mean, if an item is going to have the meaning on the right , then it MUST have the form on the left. This is a different sort of idiomatic information from knowing that kick the bucket CAN mean die, and so the different notation.

E. Williams / Remarkson lexical knowledgE

Another example like pants is fish . Fish names , with some exceptions , are all unmarked plurals or have that as an option : trout , bass, perch , bream , yellow tail , mahimahi . The exceptions are not really fish , by and large : whale , guppy , minnow . Other animal families are untouched by this idio syncracy : bee, wasp , ant . As far as I can tell , this is an unpredictable , but ' ' information very general fact about English , and counts as idiomatic about the language . A further case of the same sort is the language - particular patterns of lexicalization identified by Talmy ( 1985) . He found that languages systematically differed in the kinds of verb meanings they allowed . For example , English allows verbs of motion to indicate a means of motion . Float can be used as a directional verb , but at the same time , it indicates the manner of motion : John floated under the bridge can mean that John moved under the bridge by Boating . Spanish and French lack entirely verbs of this kind . F/otter in French and flotar in Spanish ( float ) can mean only to float stationarily , and the restriction is apparently a hard and fast one. Similarly , verbs of posture ( sit , kneel , lie , etc.) differ systematically from language to language , in whether the stative , inchoative , or causative is the basic or underived form ; English , Japanese, and Spanish systematically differ in this choice - see Talmy ( 1985) for details . Again , we have language -particular variation of a quite general sort . ' ' Again , the information is idiomatic , but the question remains , how to ' ' represent it . We might again represent it as an idiom with a hole in it :

( 13a) [inchoative)v +- : posture verb (Japane~ where V is atomic. 13b motion verb]v +- : manner (English ) ( ) [ Now , the representation here I think is not so important as the question of what this sort of information is, and especiallyhow it is acquired. I think that language-particular patterns of the kind that havejust been discussed- pants in English, the motion verbs in Romance, the posture verbs, etc. - fall outside of the ' parametric' core, and yet, they are quite general, and basically exceptionless. This means some sort of general induction , the kind that is meant to extract ' lexical reduncancyrules' , must be capable of acquiring from ' of the rule. Some substitute for the data the ' exceptionlessness negative evidence, such as counting, and statisticking, is required. And somelimitation on the spaceof searches must hold , in order for the induction to remain in the realm of possibility .

E. Williams I Remarkson lexical knowledge

The most surprising casesare the casesthat achieveexceptionlessness . The ' idiom is pants exceptionless, in that any noun that means the right thing must participate in the idiom . The presentparticiple is another case: there are no present participles that do not end in -ing whereaspast tense forms, as is well known , are quite varied. The learner learns more than that there are no exceptions; he learns that there can be no exceptions. We will discuss such cases further in sec~ion 4. For the moment, we note that the formalism , though it at the same time proposed suffices to express exceptionlessness hides the learning problem implied by them. '

2.2.2. Formal idioms: Exploited and unexploitedavenues The pants phenomenon just examined is I think more widespread. Formally ' , the grammar permits singular nouns to have the meaning such and ' such a type of legwear , but this avenue is unexploited in English, thanks to ' ' ( 12) . By unexploited avenues I mean possibilities that the formal system would seemto allow , but which it does not use. In identifying such casesone always risks missing the formal explana~ion for the missing possibility, though a case like pants I think clearly shows that there will not always be one. As one example, consider compound terms in English and French. Both languageshave meansof putting together words from further words, or kind denoting terms. In French, the syntactic system is exploited; so, one has compound terms of the following kind : ( 14

)

VP

>

>

V

>

NP

>

V

N

>

>

essuie

'

'

glace

wipe

window

' ,

windshield '

wipers VP

>

>

V

PP

>

>

V

P

N

>

>

laisse

pour

'

'

- conte

left

for

count

,

'

' abandoned

one

Here, the double carat means ' has as an instance' . So, compound terms in French are instancesof syntactic constructions. As word level items they have their own limitations (e.g., no referential material may occur in them, and so, for example, no determiners are allowed) , but they are neverthelesswellformed syntactic objects. English , on the other hand , exploits a different system to form its compound terms :

( 15) [ X Y] y > > [ NN] N

E. WUliamsI Remarkson lexical knowledge

The system exploited here is the affixation system in the lexicon, which is . Ordinarily , Y is a suffix, forming the head of a word. English right -headed ' lets Y be a full noun, giving us compounds. Importantly , both languageshave both resources- English has the same (left -headed) syntax as French, and French has the same right -headedaffixation systemas English; however, they each exploit a different one of thesefor their compound terms. I assumethat this is ' idiomatic ' - that is, language' ' particular , but perhaps not parametric .

2.3. Syntacticidioms English embeddedquestions must begin with a wh-phrase. This is not to say that Wh-movement is obligatory in English, as it clearly is not ; not only do matrix questions not necessarilyundergo Wh -movement, but even a whword in an embeddedquestion need not move, when, for example, another has moved, or the complementizeris already wh, like whether:

( 16) Who wonderswhetherGeorge saw who ? The correct generalization is as stated: a Wh -word must appear at the beginning of an embeddedQuestion. What sort of information is that ? We might describeit as an idiom , in the sensedevelopedherein:

( 17) [wh-phraseS +- : embeddedquestion That is, a sentencewith a Wh-phrase at the beginning is a question, and nothing else is. The arrow goes backwards, as any embeddedquestion must have this form . ' Idiom ( 17) is a good candidate for a ' parameter , in that there is a small number of ways that question words can be dealt with : ( I ) moved to front ; (2) moved to verb (as in Hungarian); or (3) left in situ. However, I think there is good evidencethat idioms just like ( 17) must be countenanced, ones that are not reducible to parametersof variation . One caseis the ' amount' relatives. These have the following form :

) [wh-phraseS] (18a '

> > N what S : Little (amount relatives) [ ] I him food I had. 18b what ( ) gave I him what I had. 19 ( ) give

E. Williams I Remarks on lexical knowledge

( 18b) has an implication that ( 19) does not have, namely, that there was little food in question. Now , where does this implication come from ? It does not come from what, which does not have this implication in general, not even in free relatives, exceptin the context in ( 18b) . Furthermore, it does not inhere in free relatives in general. In fact, it occurs only in the structure in ( 18), it is idiosyncratic to that structure. Assuming that there is no parameter to set here, then this is a learned fact about this structure. What is interesting is how formally similar ( 18) is to ( 17) . The only difference is that the semantics of ( 18) is very particular, and therefore plausibly idiomatic , whereas the semantics of ( 17) is very general. But the formal means may be the same in the two cases: a feature of meaning and form are connected in an idiomatic entry in the lexicon. If a learner can induce ( 18), it would seem that ( 19) would be accessible to the same mechanism. A related sort of case arises from Subject Aux Inversion in English; the following is an idiom of English:

(20) [ V S]. +- : matrix yes/no question This is comparable to ( 17) - an obligatory idiom (that is, of the pants variety) has the effect of forcing syntactic rules to apply. More interesting are the casesof inversion which receivea conditional interpretation : (2Ia ) Had I been there, this would not have happened (21b) S > > [ V S]s: conditional > > [ had...]s > > [were...]vp The rule of inversion gives a large number of forms which are ungrammatical in this context :

* (22) Could I write poetry, I would not be a linguist . In fact, inversion in the conditional context works only for the auxiliaries had a~d were. What sort of infonnation is this? Importantly , the casesallowed in the construction are a subset of the casesallowed in general; hence, what is learned is that not all the formally allowed possibilities are realized. We will adopt the following convention for representingthis situation :

E. Williams I Remarks on lexical knowledge

(23) Instanceprinciple : If a fonn to which a meaning is assignedhas listed subinstances, then those subinstancesare exhaustive. 2.4. Idiom families

At one end of the language-particular information that a learner must acquire are the completely fixed expressions; at the other end are the broad ' . I have suggestedthat there are intermediate ' abstract typologiCalparameters 0 idioms _ pants and amount relatives, for example, which link theseendpoints with a graded continuum. In compensation for this more complicated situation , and the more complex learning problem that it poses, I have suggested that each level of ' abstractness' must conform to the level above it ; thus we ' ' do not have a wholesale theory of constructions , but still a broadly parametric model. This says that a construction - say, passive must conform to the typo logical pattern that is determined by some parameter but leaves open the possibility 0that not all features of the passive .settings, construction will be determined by this conformation . As further evidence of this view, I will discuss here some idiom families, that is, language-particular idiom patterns. Each idiom pattern has a number of idioms as instances. The principle reason for recognizing the existenceof the idiom family is that somelanguageswill have idioms of a certain sort, and others will lack them altogether, apparently in a way not related to the parametric typology of the languages, though of course one could always be wrong about that for any particular case. The most interesting sort of case I know of was pointed out to me by Martin Everaert (pic.) ; the idioms are of the form :

(24) NyPNy by side The two Ns are meant to be identical tokens of the samenoun, as in side by side. French, English, and Dutch have these idioms, Japaneselacks them ' ' entirely. For this reason, we would want to call (24) itself an abstract idiom of the sort discussedin previous sections. Idiom (24) probably has as its most imniediate instantiations not actual idioms, but further , more concrete, idiom families, one for each P that participates:

E. Williams I Remarkson lexical knowledge

(25) Nx P Nx > > Nx by Nx Nx to Nx Nx on Nx Nx for Nx Nx fromNx Someof the manyexamplesof instancesin thesesubfamiliesare:

(26) N to.N > >

hour minute second year

window door station head hand cheek

NbyN > >

minute, hour , etc. ; layer house cave

N for N > > dollar for dollar N from N > > limb from limb Non N > > layer on layer If these are idioms, then we expect them to be instances of well-formed structures in the language. One is at first hard-pressed to identify what structures these are well-formed instances of , but I think the most likely "candidate is the compound prepositional phrases, asfrom . .. to:

(27) John went [from a to b] The compound prepositions generally require both prepositions to be overtly present, but this is not always so, as in the following : (28) I do not know what he is doing [one day to the next] . T1')us the compound prepositions are somewhat like conjunctions, where we find both simple (and) and compound (both ... and) varieties. It so happens that the idiom family so productive in English is a subspeciesof compound prepositional phraseswhere the first preposition is not present. In French, on

E. .Williams I Remarkson lexical know/ed~E

the other hand, both prepositions must be present: depart en part (' limb from limb ' ) ( V. Deprez, p .c. ., T . Hoekstra has pointed out to me the existenceof heurepar heure and cote a cote) . The various subcasesof (24) do not have a common element of meaning. So, for example, cheekto cheekrefers to the pressingtogether of two cheeks, as in dancing; but minute to minute and day by day refers to a seriesof days in sequence . Even the instancessharing a common proposition do not have a completely shared element of meaning, as the two instanceswith to just cited show. Therefore, these forms are not compositional, despite clear patterns in the meaning. On the other hand, from the fact that they are so prevalent in one language, and absent altogether in another, we know that they are present as a group in some sense. It seemsunlikely that there is a parameter for this property alone; perhaps it follows from some other parameters, though it is hard to seehow. An alternative is that the structure in (25)-( 27) is induced from the data of the language. How could this happen? Supposethat at a certain point in the . course of acquisition, some number of forms with the shape NxPNx have been learned. As a class, they conform to the shapeof left headedcompound prepositional phrases, and so do not fall outside of the language altogether. On the other hand, their properties are not entirely explicable in terms of the general principles of the grammar; in particular, the use of bare singular count Ns as the objects of prepositions is not a general feature of prepositional phrases in English. So these remain idiomatic ; however, they are idiomatic as a class, not as individuals. Another family of idioms is illustrated in the following : (29) John hunts bear snares rabbit traps monkey

(a) *John huntsbook * 1 am goingto gradepaper , (b) *Johncountsmonkey (c) * hunt sleepyelephant What is special about this case is the use of the bare singular as object. Normally , this is not allowed for English count nouns, but is allowed here. So, we have an abstract idiom , of the following form :

E. Williams I Remarks on lexical knowledge

(30)

N] vp [V + HUNT + ANIMAL

The form in (30) is a special case of the general form of VP (and so, for ' ' ' ' example, is V N and not N V ), and thus conforms to our overall claim that abstract idioms are always instancesof more generalpatterns of the language. The limits of this idiom are somewhat roughly indicated by (b) and (c) - the ) shows verb must be a verb of hunting, and the object must be an animald a further restriction - not only are determiners excluded, but adjectives as ' well (unless"sleepy is a kind of elephant) . One might conclude from this the observation that this construction was ' ' in fact a lexically compound verb - to hunt monkey then would be syntactically intransitive . I doubt this, since English in general disallows compound verbs, and particularly disallows left -headed compound verbs; but even if the conjecture were correct , then the problem posed by these examples is not solved, but simply delivered to the lexicon, with fee still unpaid. I . assume that it is not at all predictable that English would have this pattern ; and in fact, inspection of (b) and (c) might lead one to not expect this pattern . I conclude therefore, that learning ( 30) entails generalizing over exampleslike those in (29), and the limits of the generalization must follow in some way from the actual mechanism of generalization. The existence of these idioms of intermediate abstractness argues that learning languagedoes not reduce to (a) learning parameter settings, and (b) learning the properties of particular lexical items. Rather, there are structures between these two extremes, what I have called abstract idioms , which .can only be learned as language-particular generalizations of particular forms.

3. Paradigms A paradigm is a multidimensional array of linguistic forms - for example, a verb conjugation, or a Latin noun declension. A paradigm is not just a convenient way to display linguistic information ; rather, it is a basic form of linguistic knowledge. It interests here becauseit is highly languageparticular , and at the same time, quite abstract in structure. Paradigmatic structure is also pervasive. Example (a) below is a slice of the Latin verbal conjugation :

E. Williams / Remarkson lexical knowledge

(31) Latin : (a) + - finite + - indicative + - passive + - perfective presjimperfjfut + - plural Ij2j3person

(b) amo amamus amas amatis amat amant

The Latin verbal conjugation is 8-dimensional, with the dimensions listed on the left. It is not possibleto say in a general way how many dimensionsa paradigm will have, nor how many points on a given dimension, nor what the dimensionswill ' mean' , or what syntactic or semanticcategoriesthe points on a dimension will be taken as signifying. There are severallevels of abstraction involved in paradigms. At the lowest level, we have word -paradigms, such as in (31b). At a slightly higher level of abstraction, we have paradigms in the traditional sense, roughly speaking, setsof endings: ( 32) - 0 - as -t

-mus - atis - ant

At a slightly greater level of abstraction, one might regard a paradigm as a set of rules which, when applied to a stem, derive a word paradigm, by, for example, adding endings. So there is a rule for forming the past tense, a rule for forming the third person present tense, etc. In fact, though, I believe that a paradigm is even more abstract than that - a paradigm is a patterning which is more abstract than any set of forms, any set of endings, or any set of rules for filling the slots in a paradigm. That the paradigm is a real object, and not the epiphenomenalproduct of various rules, is shown by the phenomenaof blocking, syncretism, suppletion, and paradigm defectiveness , as argued in Halle ( 1973) . To consider only the first of these: if there are two rules for filling a slot in a paradigm, ' only one may be used; thus, we have bit , not bited, and in general, only a single past tense form for a given verb , despite multiple ways to form past tenses. This reveals that there is a target slot to fill , which .is independent of the rules for filling it , and that slot is given by the paradigm .

E. Williams / Remarkson lexical knowledge

3.1. Extensiveness

We tend to think of paradigms as a means of displaying inflectional information about the parts of speech. But in fact, the notion of paradigm is much broader than this. To begin with , paradigms must include syntactic items, or phrases, as well as words. To seethis, we need only examine a slice of the Latin verb paradigm: (33)

active passive present amo amor perfect amavi amatus sum

Here the forms are all 1st singular, present-perfective crossed with activepassive. One comer of this square contains a phrase, amatus sum, while the other three comers contain words. This shows that phrases form an inextricable part of paradigmatic information . If we removed the perfective passive form , we would have destroyed the symmetry of the paradigm, which is otherwise perfectly symmetrical. We can see the same thing in an English paradigm, the comparative paradigm:

COMP SUPER (34) A long longer longest compact morecompact most compact better best good The rule is, if an adjective is mono- (or nearly) syllabic, then form the comparative with -er ; if not , then the comparative and superlative are formed ' phrasally. The existenceof this paradigm is what pennits us to speak of the ' of an comparative adjective, even though there are two ways of forming . comparatives Many languageslack any way at all to fonn the comparative; English has two ways, one morphological, the other syntactic. Paradigms include not just inflectional dimensions, but what have been called ' derivational' processes as well. I am sure that there is no distinction be~ween derivational and inflectional morphology , but if there is, then paradigms are found in both morphologies.

E. Williams I Remarkson lexical knowledge

3.2. The abstractness of paradigm structure

In general, there is not a one-to- one relation between the slots in a paradigm and the rules for creating the fonDSwhich fill the paradigm. In one circumstance, there are more slots than rules, and therefore, severalslots will be filled with the same form - this is the phenomenon of syncretism. The pattern of syncretism that is found reveals the method of assigningforms to slots. The method consistsof the following : . ( I ) Hierarchalize the dimensionsof the paradigm. Assign forms to nodes in the hierarchy. For example, the English verbal paradigm is 4-dimensional (personX number X present-past X finite), and there are 4 distinct forms. We may hierarchize the tree and assignthe forms to it as follows :

(35)

.

I pres m sg I

2 3*

m pi

I

2 3

V * = run

V' I

I

I

finite I

infinitive I

I

I

I

past.

perf*

infinitive

rfl

rfl

I 2 3

1 2 3

rfl

rfl

I 2 3

1 2 3

* past = ran

3 * = runs

1 2 3 rfl rfl

I 2 3

perf * = run

The tenninal nodes are the actual cells of the paradigm. The starred nodes are the nodes to which actual forms are assigned. By convention, a cell is filled by the nearestspecifiedform above it . The identity of the forms and the points in the tree at which they are mapped are given in (35) . The assignment ' shown is the most economical, as each form is assignedonce. ' We might call the starred nodes entry points' - these are the points at which concrete forms are specified. The tree along with the starred nodes we

E. Williams / Remarkson lexical knowledge

' ' might call the pattern of syncretism . This is a pattern which is independent of the rules for creating the forms in the pattern. It is a part of the formal structure of the paradigm. Strikingly , the pattern of syncretism holds generally in a category, not just for particular verbs, as we will see. If we look at the pattern of syncretism for a variety of English verbs, a startling pattern emerges:

V$ I

(36)

I I pres r +- , * sg IA 2 3 r +- ,

. pI I 2 3

finite ~

I

perf *

infinitive

r +- ,

r +- ,

pastS

I 2 3

I 2 3

r +- ,

~

m

IA 2 JA

I 2 3

1 2 3

I

r +- , I 2 J

Entry points : $ modals $* regular; go-went $*" be have, says, does - irregular in 3prsg: * haves Here, marked on the same tree, are the entry points for severalcategoriesof verbs, including irregular verbs. As can be seen, the sets of entry points form a nested set; the verb be shows the most distinctions, and consequently has the most entry points, but all other verbs, including all irregulars, have some subset of the entry points of be. It is far from obvious that such a relation should exist - if a verb is going to be irregular, why should it not be irregular in having a different pattern of syncretism, a different set of entry points ? But this does not happen, even irregular verbs respectthe pattern of the language as a whole. In fact, even suppletive verbs, the limiting case of irregularity , respectsthe pattern of syncretism; the verb go has went as its past tenseform . Things could have been different: went could have been the third past plural form , with goed (or something else) for all the other forms ; but then, go-went would have violated the language-wide pattern of syncretism.

E. Williams / Remarks on lexical knowledge

Hence, the pattern of syncretism is a quite abstract structure, standing above particular words, particular rules, particular suppletive relationships. We can see this further in the noun declensions of Latin . Latin has 5 declensions, each with its own set of endings (we ignore here the genitive and the vocative) : Latin

declension structure :

< 1> 1 .

" s ~

direct r- l -, nom

indirect r - L- ,

acc

< 2>

abl s ~

,

dat

abl

acc

direct r--l --w nom acc

dat

direct r=

nom

nom

indirect . r- L- ,

acc

< 3>

abl s ~

.

nom

I

s ~

: L - ,

acc

direct . r - L- , nom

dat

indirect . r - L- , abl

dat

acc

abl

dat

direct r-- L- , nom

dat

indirect . r - L- , abl

dat

-;Il I I p

I

direct indirect r-- L, r - Li nom acc abl dat

acc

direct r ~ nom

acc

indirect . r - L- , abl

N Ac D Ab

-a - am - ae -a

-IS . - IS

N Ac D Ab

-us -urn -0 -0

-i - os - is - is

etc.

indirect . r - L- ,

I 1 1 -pi

I

abl

acc

< 4>

dat

indirect r-- L- ,

direct r - L- ,

abl

-;I1 I I p

< 2n > ~ ____~ - -- , direct r -- L- ,

indirect . r~

I I I -pi

I

indirect . r-- - L- ,

direct , . J--, nom

-;Il 1 I p

I

dat

-aeas

E. WilliamsI Remarkson lexicalknowledge < 4>

s ,

direct r- l - ,

nom acc

~

-pII

1

,

1

indirect r-- L- , abl

dat

nom

acc

abl

dat

principle syncretisms: 1st decl: pl . indirect (-is) 2nd decl:pl . indirect (is), sg. indirect (-0) neuter: above + direct sg. (-urn). pl . direct (-a) 3rd decl. :pl . indirect(-ibus) 4th decl. :pl . direct (-es) pl . indirect(-ibus) neuter: sg. (direct = indirect) (-0), pl . indirect, pl . direct Here, the nominative and accusativehave beengrouped together as ' direct' , and the ablative and dative as ' indirect ' . The reason for this is that this reflects the patterns of syncretism: nominative and accusative fall together sometimes, and dative and ablative do as well. A striking thread that runs through the entire set of declensionsis the indirect plural syncretism. In the singular, there is an indirect entry point for 2nd and 4th neuter; the plural syncretism holds across the board. Importantly , this generalization is independent of the rules for forming the indirect forms, for in fact there are two different rules for that : in the first and second, -is is affixed; whereasin the 3rd and 5th, -;bus is affixed. Hence, the pattern is more abstract than the rules or affixes. I would suggest that a pattern is abstracted that applies to all the declensions, essentially the tree structure in -< I > . Other declensionswill make further syncretisms, but this one will hold for all. A general conclusion we may draw is that when there are multiple related paradigms, there will be one instantiated paradigm, and all others will have its syncretic structure, and perhaps some more. But no other related paradigm will have a contrary syncretic structure, making distinctions where that one does not. We will call that one paradigm the basic paradigm. For the Latin nominal declension, the first declension is the basic paradigm . For English verbs, the verb to be is the basic paradigm. L,et us now consider Latin verbs. Every finite Latin verb form has a different form , so there is no syncretism at this level. But at the level of stem, there is a paradigm structure with a limited number of entry points. Below is a chart of the stem forms for various classesof Latin verbs:

E. Williams I Remarkson lexical knowledge

.. (37) Latin verbstemsuppletion Vx I I . I

perf *

I

I

A imperfect

future .

Z'

.

I

sg ------ ---+- , , 1

partic

I

I pres I

I

I

r

' 3

I

plur - - ------" , 1

2'

3

Entry points for stem : * A' esse edo , * A' volo *A regularized volo * A do * regulars , including fero feri Tull latus x amo

The asterisked positions represent the entry points for the regular verbs of all four conjugations. This alone is striking , for again, there are different rules in the different conjugations for yielding the forms at these entry ' ' points . The first and second conjugation form the future by suffixing -b- , whereas the third suffixes nothing , but switches the conjugational class of the basic stem. Neverthess, that the future is an entry point is common to all the conjugations. The verb essehas the most entry points, and every other verb uses some subset of those entry points. Thus the conjugation of esse is the basic conjugation, to which all the others are related. ' As a final example, we consider Anderson s ( 1984) description of Georgian ' verb conjugation. The system is quite complex; Anderson s account uses blocks of rules, both conjunctively and disjunctively ordered. It is my contention that such a systemwill fail to capture the most abstract patterning of a paradigm, which, as we have seen, is generally independent of affixes or

E. Williams / Remarkson lexical knowledge

rules. Someindicationthat this is so can be derivedfrom the following table of affixes(or, to useAnderson's accountmore directly, of rules for adding affixes ) for presentand past: (38) present -en 3pl subj -t pi -s 3rd subjects

past -es 3pl subj -t pi 3rd subject

' ' The rules are.quite similar, and Anderson s remark This -es rule has the same status as the -en rule in this block , and also takes precedenceof the -s and the -1 rules ...' ( 1984: 8) shows I believe that an abstract structure is being replicated in different parts of the paradigm, thus underscoring the independence of that structure from actual rules or affixes. 3.3. Learning paradigm structure We ask at this point , why are these patte .rns of syncretism in language ? Why is a pattern of syncretism replicated accross different modes of realizing paradigm cells? I speculate that it is the acquisition of paradigm structurethat is respon

sible for this arrangement. Pinker has demonstrated how the blocking principle will give rise to the developmentof paradigm structure in the languagelearner. The basic idea is that wheneverthe languagelearner has been forced to posit two items to fill a single cell, he is then motivated to split the paradigm (really, to double it ) so as to avoid violating the blocking principle : (39)

D

The paradigm now has a new dimension, and a whole new set of cells; the ' ' language learner now must learn the significance of the dimension, and fill in the rest of the cells. I think that this algorithm for building paradigms, combined with the notion of paradigm structure I have just outlined, will predict some of the patterns we have observed.

E. WilliamsI Remarkson lexicalknow/edgE

There are two sorts of splitting than can take place - intraand interparadigm ' ' splitting . Given a present tense paradigm for some verb, see, for ' ' ' ' example, the recognition that saw , like see, can be used for the 1st person ' ' singular, leads to a postulation of a past tenseplane, in which to locate saw . This is intraparadigm splitting . The other kind of splitting might be called ' declensional' splitting : given a set of endings, say the endings for the 1st declensionin Latin (-a, -am, -De, -a, etc.), the recognition that the ending -us can signify nominative singular, just as -a does, triggers the splitting of the nouns into (at least) two declensions. The differencebetweenthis and the first caseis that in the first case, a given word will have forms in every cell of the new and old plane, but in the second, a word will have forms in only a single declension. We may neverthelessconsider the splitting to be formally the same in the two cases, and this is supported by the observation that syncretism patterns the samein the two cases. An example of a ' declensional' split is the comparative paradigm in English; the paradigm is a linear three-point paradigm: adjective, comparative , superlative. But there are two modes of forming members, as we have . seen- one for monosyllabics and Simple disyllabics, and another for everything .else. A telling point which showsthat we are dealing with a declensional here is that the same criterion that is used to determine whether the split ' ' comparative is A -er or more A is used to determine whether the superlative ' ' is A -est or most A . This criterion is not therefore a part of the rules themselves , but is rather a general criterion of membership in the two declensions; much as ' feminine' is a criterion for membershipin the Latin 1st declension. Now , supposethat a learner has learned a piece of paradigm structure, and has learned not only the labels for the dimensions, but has also learned the positioning of the entry points, which I have called the pattern of syncretism. Supposefurther that when the paradigm is split, that this abstract pattern of syncretismis replicated along with the cells themselves:

(40)

0 If this is done, then we will expect to seepatterns of syncretismrecurring. The following prediction is made: whatever paradigm is learned first will embody

E. Williams / Remarkson lexical knowledge

the most distinctions. This is becausecells which are designated identical by the pattern of syncretism of the first pattern will remain identical in latter versions. There may be fewer distinctions in later folds , but not more. Thus for example when the learner learns the first declension, with its indirect plural syncretism, and then learns that there is a second declension, that same indirect plural syncretism will show up in the second declension as well , copied as a part of the abstract structure of the first declension.

4. Learning .words 4.1. Learning morphemes

The notion of an abstract paradigm, the blocking principle , and paradigm splitting may account for how a paradigm is elaborated, but what accounts for the identification of a (potential) paradigm in the first place? One ordinarily thinks of verbal paradigms, re.alizing person, number, tense reference, etc., as the typical par~digm, but in fact languages have novel paradigms that it is unlikely coul.d be specifically anticipated in UG . Supposethat one component of the learner is a device that usesextra cycles in the child ' s computational life to track down statistical correlations among various properties of its thus far stored linguistic units. What the set of properties is will not detain us here. The child learning English, for example, will discover a correlation betweenwords ending in -yand adjectivehood:

, etc. (4Ia) fishy, lumpy, lucky, speedy

(41b) dainty

, pretty , happy , etc .

Many adjectives do not end in -y , and many words ending in -yare not adjectives, but the probability that a word is an adjective increasesonce one knows that it ends in -yo Note that this is true for a large class of adjectives where the -y does not serve as a suffix (the second group) . Even excluding the caseswhere -y is an affix, there is a correlation. A battery of such correlations could serve the next step: to identify m~rphemes, and assign them properties. In the case of -y - + A , there are sufficient casesto warrant postulating a suffix with the category adjective, and assign it wherever possible - that is, wherever an independent stem exists.

E. Williams I Remarkson lexical knowledge

Even where the analysis into morphemesdoes not hold , the information of the correlation has been noted; it seemsunlikely that this information is forgotten once the morpheme has been established. Another example in English of a no- go morpheme is the suffixtude ; most of the 50 or so membersdo not admit an analysis into morphemes:

(42) altitudeattitudeplatitude, And yet, this suffix so strongly marks nounhood that there is not a single verb or -adjective with this ending. The number of examples it takes to establish a correlation between two properties is quite small. For example, the English noun-deriving suffix -af has fewer than 20 instances; and yet, the correlation between suffix and category seemsfirmly established for all speakers, as well as the restriction that the stem must be stressfinal , a separatelearned correlation : (43) betrothal, avowal, approval, removal ... The confidenceof theseidentifications is surprising given the small number of casesinvolved. S6, there are two levels of analysis so far ; first , the identification of correlating properties, and second, the postulation of analysisthat arisesfrom this. Units will be postulated that account for the correlation. There is a further level of analysis, I believe. In somecases, it is detennined by the learner not just that two properties correlate, but that one of the properties is uniquely correlated with the other property . We might suppose that children are built to look for this especially. Severalexampleshave been examined in this paper. One is the idiom Ns : ' ' ' wear on the ' legs ; the property of meaning wear them on your legs is ' ' uniquely correlated with nouns that end in s . Another is the progressive, which is uniquely corellated with V + ing. I believe that the uniqueness has special salience. It is what we might consider the ' ideal' case, and so the first sought and most readily accepted. We know , for example, that the past tense forms of verbs in English are irregular, and some are in fact suppletive. Given this, we are not surprised so much to learn new verbs with irregular past tenses. However, I think we would resist entirely learning a new verb with a suppletive progressive, a progressivethat did not end in -ing.

E. Williams I Remarks on lexical knowledge

4.2. Learningsubsystems In orderto geta paradigmgoing, onemustnoticeparallelcorrelations . For , in English, thereis a Latinateparadigm, of the following shape: example (44) verb

adjective

de- verbal noun

de-adjectival noun

conclude conclusive conclusion conclusivity

The strength.of this paradigm is great enough that when a coined word meets the criterion for membership , it immediatelyparticipatesin the entire paradigm: (45) subduct: subductive: subduction: subductivity How do we know that we are dealing with a paradigm here, and not simply with several distinguishable morphological rules? Becausethe correlations amongst the rules striking : for example, 80%' of the words that take -ive to form adjectivestake -ion to form nouns; this is as compared to the baserate of 6% of nouns that take. -ion. Surely speakersnotice this sort of correlation , and use it to construct a paradigm like (44), which can then be exercisedon new forms. The criteria for membership in this paradigm are somewhat rough, but include at least the following :

(46) word = prefix-stem prefix = {trans, sub, super, de, dis, con, etc.} stem= CVC(C). The force of thesecriteria can be seenin the fact that 26% of the nouns that begin with trans- fonn nominalizations in -ion, against the base rate of 6% for nouns in general. Incidentally, this sort of thing is not limited to the English Latinate vocabulary. 39% of the verbs beginning with the causative prefix enencroach , endear, encase , ensnare) form their nominalization in -ment, as opposed to the background rate of lessthan 5% . ' ' We ordinarily think of -ion as an unproductive suffix, compared, say, to the suffixness . However, as we have seen, in the domain of certain classesof stems, -ion approachescomplete productivity , and even becomesapplicable to new forms. The other side of the coin is that -ness is actually not so

E. Williams I Remarkson lexical knowledge

productive over the entire set of stemsin English - it is of course only in the adjectives that it shines. So -nessand -ion are equally productive, we might say, over their own classes- the class for -nessis adjectives, and the class for -ion is Latinate verbs. Given this, we might wonder, why isn' t every affix completely productive within some arbitrarily drawn subclassof the lexicon, say the class of things to which it does attach? I think the answer is that subclasses cannot be arbitrary . The Latinate class is productive for -ion precisely becauseit can be identified independently of the occurencesof -ion: it can be identified as the claSsto which -ive attaches, or perhaps it can be identified in some way along the lines of (46) . In either case, we must attribute to the language learner the ability and the inclination to compare subclasses, and look for high matches. When a high match is found , then a dimension of a paradigm has been identified.

References . NLLT 2, 157-218. in morphoiogy . On representation . Anderson , S., 1984 . . On the definitionof word. Cambridge Disciullo, A.M. and E. Williams, 1986 , MA : MIT Press . . Semanticconditionson surfa(:e structure. MIT dissertation Fiengo, R., 1974 . Prolegomena to a theoryof word formation. LinguisticInquiry 4, 3- 16. Halle, M., 1973 . Patternsoflexicalization.In: T. Shopen(ed.), Languagetypologyand language Talmy, L., 1985 . . Cambridge , MA : CambridgeUniversityPress description . On the notions'lexicallyrelated'and ' headofa word' . LinguisticInquiry 12, Williams, E., 1981 245-274.

) 35- 77. North-Holland Lingua92 ( 1994

A preliminary analysis of causative verbs English*

in

BethLevina.and Maika RappaportHovavb . Department , Northwestern , 2016SheridanRoad, Evanston , IL 60208 of Linguistics University 4090, USA . Department , Bar lIan University , RaniatGan, Israel52900 of English This paper investigates the phenomena that come under the label ' causative alternation ' in English, as illustrated in the transitive and intransitive sentencepair Antonia broke the vase/ The vasebroke. Central to our analysis is a distinction between verbs which are inherently monadic and verbs which are inherently dyadic. Given this distinction , much of the relevant data is explained by distinguishing two processes that give rise.to causative alternation verbs. The first , and .by far more pervasiveprocess, forms lexical detransitive verbs from certain transitive verbs with a causativemeaning. The secondprocess, which is more restricted in its scope, results in the existence of causative transitive verbs related to some intransitive verbs. Finally , this study provides further insight into the semantic underpinnings of the Unaccusativity Hypothesis (Perlmutter 1978).

I . Introduction is particularly rich in verbs with both transitive and intransitive . English uses where the meaning of the transitive use of a verb V can be roughly ' ' paraphrased as cause to V- in transit ive . Such verbs are illustrated in ( 1) and ( 2), where the transitive (a) sentences might be paraphrased in terms of the ' ' intransitive ( b ) sentences; that is , as Antonia caused the vase to break and ' ' Pat caused the door to open . . Thiswork waspresented at theWorkshopon theAcquisitionof the Lexiconat the University in January, 1992 . We would like to thank the other workshopparticipantsand of Pennsylvania ' . This work was also , for their comments particularly Tony Kroch, the papers discussant in March at Hebrew , 1992; we are grateful to the audiencefor their University presented . This paperhasalso benefitedfrom the commentsof Mary Laughren comments , StevePinker, . We wouldlike to thankJohnWickbergfor helpingus BetsyRitter, andan anonymousreviewer wassupportedin part by NSF Grant BNSin on-line texts. This research find relevantexamples . 8919884 - 3841/94/$07.00 (Q 1994- ElsevierScienceB.V. All rightsreserved 0024 -9 SSDIOO24-3841( 93) EOO38

B. Levin, M. RappaportHovavI Causative verbsin English

( la ) ( I b) (2a) (2b)

Antonia broke the vase. The vase broke. Pat opened the door. The door opened.

We refer to this alternation as the causative alternation and to verbs with both uses as causative alternation verbs. 1

Such transitive/ intransitive pairs have receivedconsiderableattention from linguists . working in a variety of linguistic frameworks: analyses of this phenomenon have ranged from the primarily syntactic (e.g., Burzio 1986) to the primarily semantic (e.g., Fillmore 1968) and from the wholly lexical (e.g., Wasow 1977, Keyser and Roeper 1984) to the partly lexical (e.g., Borer 1991). 2 There is a sensein which, at least descriptively, the phenomenon is taken to be well-understood, and the same handful of acceptedfacts regarding this phenomenon are frequently cited. 3 Although the analysis of this phenomenon has been the focus of many studies (see, for example, the referencescited in Levin 1993), relatively little has been said about the phenomenonexcept in relation to the multifarious theoretical concernsit has been used to shed light on. It turns out , however, that many important questions about the phenomenon itself remain unanswered. And as long as the phenomenon itself is still not well-understood, a complete analysis of the alternation cannot be devel' causative which is 1 Besidesthe causativealternation. English also has a ' periphrastic . with the verbsmakeor have. asillustratedin Antoniamadethevasebreak. It hasoften expressed ' that entersinto the relationbetweenthe transitiveand beenremarkedthat the notion of 'cause than intransitiveusesof the alternatingverbsallowsfor a morerestrictedrangeof interpretations that found in English periphrasticcausatives . The type of causationassociatedwith the . . manipulative alternatingverbswhicharethesubjectof our studyis termeddirect(or. sometimes allow indirectas well as contact. or immediate . while Englishperiphrasticcausatives ) causation directcausation(Comrie1981 . among . Cruse1972 . NedjalkovandSilnitsky1973 . Shibatani1976 with alternatingverbsin Englishis not others). As we shallsee. the type of causativeexpressed availableto all verbs. contrastingwith the type of causativeexpressedby the periphrastic . In somelanguages both directand constructionin English.whichis generallyavailable causative indirectcausationaremorphologicallyencoded . the two typicallyinvolve . but in suchlanguages distinctmorphologicaldevices . We referto the kind of causativewearefocusingon in this paper of a languageand as the lexicalcausative . sinceit is usuallyformedusingthe lexicalresources showsthe hallmarksof a lexicalprocess( Wasow1977 ). 2 The causativealternationhas also attractedconsiderableattention outsidethe theoretical and child linguisticsliterature. It is the subjectof a numberof studiesin psycholinguistics ) for a reviewof this literature. languageacquisition; seePinker( 1989 3 Two notableexceptions are Pinker( 1989 ). ) and Haspelmath( 1993

verbsin English B. Levin, M. RappaportHovavI Causative

oped. For this reason, before presenting our analysis of the causativealternation , we provide a survey of certain properties of the causative alternation aimed at providing a contribution towards filling this gap in our understanding . This facet of our investigation focuseson two related questions: (i ) Is it possibleto delimit semantically the classof verbs which participate in the alternation? and (ii ) Do all examplesof the causative alternation as defined above represent instances of a single phenomenon? Answers to these questions will not only help us understand the causativealternation itself, but they should also deepenour understanding of the nature of lexical representation and its relation to syntactic structure. In this paper, we hope to show that the phenomenathat fall under the label 4causativealternation' are on the one hand lessidiosyncratic and on the other hand less uniform than is typically believed. We suggestthat much of the data we investigate is explained once we distinguish two processes that give rise to transitive and intransitive verb pairs.4 The first , and by far more ' pervasive process, is the one which forms lexical 4detransitive verbs from some transitive causative verbs. The second, which is more restricted in its sCQpeforms causative verbs from some intransitive verbs. With respect to intransitivity , we hope to provide further insight into the semantic underpinnings of the Unaccusativity Hypothesis, the hypothesis proposed by Perlmutter ( 1978) that the class of intransitive verbs consists of two subclasses, each associatedwith a distinct syntactic configuration . Finally , as in our previous work , we hope to show that if the relevant aspectsof meaning of a verb (or class of verbs) are properly identified, many of the apparent idiosyncratic properties of that verb (or verb class) fall into place.

: The propertiesof the alternation 2. Background that need to This section sets out the properties of the causative alternation that made observation the often be accounted for . We begin by repeating 4 That is, disregarding those verbs which participate in the unspecifiedobject alternation (e.g., the verb eat as in Terry ate her lunch/ Terry ate). In this paper, we also do not discussthe middle construction (e.g., Bread cuts easily) ; this construction involves intransitive uses of transitive verbs which at least on the surface show some similarity to the intransitive variant of the causativealternation. We consider the middle construction to be a distinct phenomenon since it differs from the intransitive variant of the causative alternation in interpretation and other properties (Keyser and Roeper 1984, Ruwet 1972, among others) ; however, seeHale and Keyser ( 1987) for an analysis that treats the intransitive variant of the causative alternation as a special caseof the middle construction.

B. Levin. M . Rappaport Hovav I Causativeverbsin English

there are many verbs in English which occur in the transitive/ intransitive pairs characteristic of this alternation. A preliminary list of such verbs is given below. ( 3) bake , bounce , blacken , break , close, cook , cool , dry , freeze, melt , move , open, roll, rotate, shatter , spin , thaw , thicken , whiten , widen , ...

Furthennore, the counterparts of these verbs in other languages occur in transitive/ intransitive pairs characterized by the same semantic relationship. In some.languages, as in English, the relation is not morphologically mediated ; see the Basque example in (4). 5 In other languages, the relation is morphologically mediated in some way, as in the French example in (5), where the reflexive clitic se is associatedwith the intransitive member of the pair . 6

(4a) Mirenekateaireki duo Miren-NORK door-NOR open3sNOR-have-3sNORK ' Miren

(4b)

(Sa) (Sb)

' opened the door. Atea ireki da. door-NOR open 3sNOR-be ' The door ' opened. Marie a ouvert la porte. ' Marie ' " opened the door. ' La porte s est ouverte. ' The door ' opened.

The existenceof this phenomenonin a wide range of languagessuggeststhat the causativealternation is not idiosyncratic to English. Studies of the causative alternation going at least as far back as Jespersen ( 1927) have suggested that this alternation is found with a semantically 5 In Basque the change jn transitivity is accompanied by a change in the auxiliary accompanying the verb. Simplifying somewhat, the transitive use selectsthe transitive auxiliary ukan ' have' while the intransitive use selectsthe intransitive auxiliary izan ' be' . Thus the difference in , auxiliary reflects general properties of Basqueand not properties of the alternation. The labels ' NO R' and ' NO R K ' are the traditional namesfor the casesassociatedwith the noun phrasesin . the examples. SeeLevin ( 1989) for more discussion. 6 For more on the morphological relationships between the verb forms in the transitive and intransitive variants of the causative alternation, see the discussion of Nedjalkov ( 1969) and Haspelmath ( 1993) at the end of section 4.

B. Levin. M . Rappaport Hovav / Causativeverbsin English

coherent classof verbs. In order to determine whether this suggestionreceives support, we can ask the following rather simplistic questions: (i ) Do all intransitive verbs have transitive counterparts with the appropriate paraphrase ? and (ii ) Do all transitive verbs with a causative meaning have intransitive counterparts with the appropriate meaning? We begin with a discussionof the first question. The following examplesshow that there are undoubtedly intransitive verbs which do not have transitive causativecounterparts. 7 (6a) The children played. * (6b) The parents played the children. (cf. The parents made the children play.) (7a) The actor spoke. (7b) * The director spoke the actor. (cf. The director made the actor speak.) Sa The audiencelaughed. ( ) * (Sb) The comedian laughed the audience. (cf. The comedian made the audiencelaugh.) These examples might suggestthat agentivity is the crucial factor and that agentive verbs do not participate in the alternation , while non-agentive verbs do. As it happens, both suggestionsare wrong. There are agentive verbs which do show the causativealternation, as in (9) and ( 10), and non-agentive verbs which do not , as in ( 11)-( 14) . (9a) (9b) ( l Oa) ( lOb) ( 11a) ( 11b) ( 12a) ( 12b)

The soldiers marched to the tents. The general marched the soldiers to the tents. The horsejumped over the fence. The rider jumped the horse over the fence. The cactus bloomed/ blossomed/flowered early. * The warm weather bloomedjblossomed/flowered the cactus early . The neglectedwound festered. * The heat and dirt festeredthe neglectedwound.

'7 Some English intransitive verbs without transitive causativecounterparts are used transitively in the resultative construction, but in this construction such verbs do not have the transitive causative meaning which the alternating verbs have. Consider the verb laugh in the resultative construction The crowd laughedthe actor off the stage. This construction does not mean that the crowd made the actor laugh, which would be the interpretation that would parallel the intended interpretation of (8b), but rather that the crowd laughed.

B. Levin Hovav/ Causative in English verbs , M. Rappaport

(13a) The jewels glittered/sparkled. (13b) * The queen glittered/sparkled the jewels. (14a) The stream burbled/ roared. (14b) * The rocks burbled/ roared the stream. The examples in ( 15) and ( 16) illustrate a further complication involving the transitive use of agentive verbs of manner of motion : the directional phraseswhich are optional in the intransitive use of theseverbs are obligatory in their transitive use. 8

(:I Sa) (:I Sb) (:I Sc) (:16a) (:16b) (:16c)

The soldiers marched (to the tents) . The general marched the soldiers to the tents. " The general marched the soldiers. The horsejumped (over the fence) . The rider jumped the horse over the fence. ' The rider jumped the horse.

.The behavior of the agentive verbs of manner of motion contrasts with that of non-agentive verbs of manner of motion , which, as shown in ( 17), do not require a directional phrase in either their transitive or intransitive use. ( 17a ) The ball bounced / rolled ( into the room ) . ( 17b ) The boys bounced / rolled the ball ( into the room ) . Although manifested

various

researchers

by agentive

have

verbs of manner

commented of motion

that

the alternation

is qualitatively

as

different

8 There may be some disagreement about whether the directional phrases are absolutely necessaryin the transitive causative usesof these verbs, particularly with a verb like jump . But even if thesephrasesneed not be expressedin certain circumstances, they are always understood in the transitive causative use. A speaker who accepts ( 16c) stin cannot give this sentencethe interpretation that the rider made the horse jump in place; rather this sentencereceives the interpretation involving the directional phrase: the rider made the horse jump over something. We look at this issuein more detail in section 8, where we also discusssome verbs of manner of motion that do not have causativeforms even in the presenceof directional phrases. Verbs of manner of motion are not unique in imposing the directional phraserequirement. The behavior of agentiveverbs of position parallels that of agentiveverbs of manner of motion in that they can have a causativevariant only in the presenceof a directional phrase, which givesthem an ' ' assume . position reading: MDUdestood the baby versusMDUdestood the baby on the table. We do not discussthis data here becausethis classof verbspresentsa number of complications. SeeLevin and Rappaport Hovav (to appear) for more discussionof verbs of position, as well as a discussion of a directional phrase requirementthat surfacesin certain circumstanceswith verbs of emission.

B. Levin. M. Rappaport Hovav/ Causative verbsin English

from that shown by verbs such as break (Cruse 1972, Hale and Keyser 1987, among others), we include this alternation among the data that needsto be accounted for since the general form of the alternation is the same: the transitive and intransitive usesof theseverbs differ with respectto the notion of ' cause'. Aside from Pinker ( 1989), previous researchershave taken the central property of these verbs to be that when intransitive they require agentive subjects, noting that this property appears to be carried over to the object of their transitive causative use. This work disregards the change in status of the. directional phrase. In contrast, we believe that the directional phrase is the key to explaining why theseverbs show the alternation. On the other hand, the contrast between ( 15)-( 16) and ( 17) suggeststhat , although there are agentive verbs which participate in the alternation as we have initially defined it , this alternation may be an instance of a different phenomenon , as we propose in section 8. Jespersen ( 1927) calls the classof causativealternation verbs the ' move and ' change verbs, becauseit includes a variety of verbs of motion and verbs of change of state. The list of alternating verbs presented in (3) can easily be divided into two subclasses along theselines: ( 18a) bake, blacken, break, close, cook, cool, dry, freeze, melt, open,

shatter, thaw, thicken, whiten, widen.

(ISb) bounce, move, roll, rotate, spin,

...

To the extent that verbs of motion involve a change of position (though not ' ' necessarilya translation through space), the set of move and change verbs ' ' might be given the unified characterization verbs of change. . This semanticcharacterization, although on the right track , is nevertheless inadequate. As we will see, change of state verbs do constitute the core of the class of intransitive verbs which alternate. However, to the extent that verbs of manner of motion like run are verbs of motion , it remains to be explained why they cannot appear in this alternation without directional phrases (in contrast to non-agentive manner of motion verbs like ro//). There are also verbs manifestingthe causativealternations which cannot be readily characterized as verbs of change. These include verbs of sound and light emission and verbs of position . ( 19a) The bell buzzed/rang. ( 19b) The postman buzzed/rang the bell. (20a) The flashlight beamed/shone.

B. Levin Hovav/ Causative verbsin English , M. Rappaport (20b) We beamed/shone the flashlight. (21a) Tony hung the laundry on the clothesline. (21b) The laundry hung on the clothesline. Furthennore, different classesof verbs participate in the alternation to varying degrees, a fact which itself is in need of an explanation. Verbs of change figure most prominently and most regularly in the alternation. Some, though by no means all , verbs of emission - whether they describe the emission. of sound, light , smell, or substance - can alternate. We have presented examples that show that among the verbs of light emission, the verbs beam and shine alternate, but the verbs glitter and sparkle do not. Similarly, among verbs of sound emission, the verbs buzz and ring can alternate, but the verbs burble and roar do not. Verbs of position allow the alternation rather freely. Not only hang, but also the verbs lean, sit , and stand allow the alternation, although a few verbs of position, including slouch and loom, do not. The behavior of slouchis particularly interesting since this verb is rather close in meaning to lean. (22a) (22b) (23a) (23b) (24a) (24b)

The ladder leaned against the wall. 1 was leaning the ladder against the wall. The surly youth slouchedagainst the wall. * 1 slouched the surly youth against the wall. The bear loomed over the sleepingchild. * The giant loomed the bear over the sleepingchild.

To summarize, our discussion so far has focused on the first question: whether all intransitive verbs have transitive counterparts with the paraphrase appropriate to the causative alternation. We have seenthat the intransitivity of a verb is not sufficient to ensureits participation in the alternation. Nor is the semantic notion 'change' sufficient, since although verbs of change are generally found in this alternation, intransitive verbs of other types differ in their behavior with respectto the alternation, even when they are membersof the same semantic class. Some other properties besides intransitivity and ' ' change must be found, and presumably the properties isolated will help to explain the behavior of the verbs in the different classes. We turn now to the second question: whether all transitive verbs whose ' ' meaning involves a notion of cause have related intransitive usesthat lack this notion . Again , the answer is ' no' . There are verbs which meet the semanticcriterion , but which do not have related intransitive uses. Examples

B. Levin, M . Rappaport Hovav I Causativeverbsin English

include the verb cut, which Hale and Keyser ( 1987) define as in (25), or kill , which has been defined - albeit controversially - as ' cause to die' (Lakoff 1970, McCawley 1968, among others).

in materialintegrity (25) cut: [x cause[y developlinearseparation ], by sharpedgecominginto contactwith latter] : (10 (HaleandKeyser1987 (26a) Thebakercut thebread. ' ' (26b) *Thebreadcut. (on theinterpretationThebreadcameto becut) . (27a) Theterroristkilledthepolitician * 27b The killed . ( ) politician Verbs close in meaning to cut such as slice or carve do not show the alternation ; neither do verbs related to kill , such as murder and assassinate.

(28a) Thechiefsliced / carved the turkey . . (28b) *Theturkeysliced /carved (29a) The terroristassassinated /murderedthe politician. (29b) *The politician assassinated /murdered. Moving to other domains, verbs of creation also do not participate in the alternation, although creation is sometimesdescribed as ' cause to exist' or ' causeto come to be' e. . ( g , Dowty 1979: 91) . (30a) (30b) (3Ia ) (3Ib )

Anita Brookner just wrote a new novel. * A new novel wrote. The contractor built another house. * Another house built .

Even more interesting is the fact that many morphologically complex English verbs formed with the suffixes -ize and -iff lack intransitive counterparts ' ' , 9 although these suffixes can be consideredto be causative affixes. (In fact, -iff comes from the Latin word for ' make/ do' .) Consider the examples below: .(32a) The farmer homogenized/pasteurizedthe milk .

/pasteurized (32b) *Themilk hom0genized

9 This property of -;ze is also noted by Keyser and Roeper ( 1984).

B. Levin, M . Rappaport Bovav I Causativeverbsin English

(33a) Carlahumidifiedher

. apartment * ( 33b) Her apartment humidified . However , some of these : type: counterparts of the appropriate

(34a) (34b) (35a) (35b)

complexverbs have intransitive

I solidifiedthe mixture. The mixturesolidified. The cook caramelizedthe sugar. The sugarcaramelized .

The behavior of -ify and -ize verbs contrasts strikingly with that of English verbs formed with the suffix -en. The suffix -en is also arguably a causative suffix, but verbs with this suffix appear to show the causative alternation rather more freely.

./ Thebana~as ripened. (36a) I ripenedthe bananas . (36b) I loosenedthe rope./ Theropeloosened ./ Thesaucethickened. (36c) John thickenedthe sauce (Lakoff 1968: (37a), (4a As part of a study that attempted to identify causative alternation verbs automatically in a machine-readable version of the Longman Dictionary of Contemporary English (Procter et al. 1978), Fontenelle and Vanandroye ( 1989) found that only 14 out of the 82 -ify verbs in that dictionary participated in the alternation , contrasting with 46 out of the 84 -en verbs. Unfortunately , they did not provide figures for -ize verbs, but an examination of the machine-readable version of a comparable dictionary, the Oxford AdvancedLearner's Dictionary (Hornby 1974), suggeststhat 14 out of the 78 -ize verbs listed as headwords in this dictionary participate in such pairs. 10 The contrasting behavior of these morphologically complex verbs formed with ' causative' suffixes again calls into question the existenceof a correlation betweenthe presenceof a notion of 'cause' in a verb' s meaning and a verb' s ability to show the alternation. It appears that neither intransitivity nor a ' ' meaninginvolving cause is sufficientto ensureparticipation in the alternation. 10 Thesmallnumber of -ify and-izeverbslistedin thesedictionaries canbeattributed to their intended function : thesedictionaries arerelativelysmalldictionaries for learners of designed . However examination of a moreextensive list of suchverbssuggests that . a preliminary English thenumber of alternating verbsreallyis notthathigh.

B. Levin, M. RappaportBovav/ Causative verbsin Englisll

Before presenting our own account of the alternation, we turn to an examination of an additional factor that intervenesin determining participation : selectionalrestrictions. The shared semantic relation betweenthe transitive and intransitive variants of causative alternation verbs has sometimes beendemonstrated via the existenceof selectionalrestrictions that are shared by the subject of the intransitive use and the object of the transitive use (Fillmore 1967, among others) . For example, only physical objects with certain characteristics can break, a property reflected in the set of possible objects of transitive break and possible subjectsof intransitive break. (37a) (37b) (38a) (38b)

Antonia broke the vase/ the glass/ the dish/ the radio. The vase/the glass/ the dish/ the radio broke. * Antonia broke the cloth the / paper/ the innocence. * The cloth the the innocence broke. / paper/

Assuming that selectional restrictions reflect the meaning of a verb, then this pattern of selectional restrictions reflects the fact that both variants share a common core of meaning. However, the extent to which selectionalrestrictions are shared acrosssuch pairs is not as great as is often thought . Smith ( 1970), whose study of the factors that determine participation in this alternation we come back to in section 3, points out that some intransitive verbs that typically do not enter into such alternations may enter into them for certain specific choices of subjectsof the intransitive use, as shown in the following examples.

(39a) (39b) (40a) (40b) (4Ia) (4Ib) (42a) (42b)

The baby burped. The nurseburpedthe baby. (Smith1970 : (36a The doctor burped. *The nurseburpedthe doctor. (Smith1970 : (36c The bell buzzed . The postmanbuzzedthe bell. The beesbuzzed . *The postmanbuzzedthe bees.

The exampleswith the verbs burp and buzz show that selectional restrictions need not be identical for the corresponding arguments in the transitive and intransitive uses. In theseexamples, the set of possibleobjects of the transitive use are a subsetof the set of possible subjectsof the intransitive use.

B. Levin. M . Rappaport Hovav I Causativeverbsin English

The lack of common selectional restrictions is even more pervasive. There are also instances of the reverse phenomenon: a verb which when used transitively is found with a set of objects that is larger than the set of subjects the sameverb allows when used intransitively . To take one example, consider the verb clear, a deadjectival verb that presumably means ' cause to become clear' . This verb is found in causativepairs as in (43), yet, although one can clear a table or a sidewalk, the table and sidewalkcan' t 'clear' , as shown in (44). (43a) (43b) (44a) (44b)

The wind cleared (up) the sky. The sky cleared (up). The men cleared the table/ the sidewalk. * The table the sidewalk cleared. /

A similar example involves the verb peel. This verb does not alternate at all in its most literal sense' remove peel from a fruit or a vegetable', although it can be used intransitively to describethe removal of skin - a ' peel' -like covering from a body part . The intransitive use ~f peel seemseven to be preferred in .the use in (46) . 11 (45a ') (45b) (46a) (46b)

1 peeledthe orange. * The orange peeled. 11peeledmy nose. My nose was peeling.

The examplesin (43)-(46) show that for some causativealternation verbs the selectional restrictions on the object of the transitive and the subject of the intransitive do not always coincide exactly. 12 The transitive object or the intransitive subject may show narrower restrictions. Presumably, for those choicesof arguments where these do not have transitive or intransitive uses, they lack them for the same reason that some verbs never have them. To summarize, an account of the causative alternation as defined in the broadest sensemust explain why someverbs show this alternation freely, why 11 This examplewas inspired by a similar examplein Rothemberg( 1974 ), a study of a comparablephenomenonin French, which includesmany examplesof divergingselectional restrictions . 12 It is possiblethat a closerexaminationof a widerangeof verbsmayshowthat theselectional restrictionsdo not coincidefor any verb. For instance and Ritter , as pointedout by Brousseau of the verb breakwherethe overlapis not complete : H~ brokehis ( 1991 ), thereare evensenses promisebut * His promisebroke.

B. Levin, M.

Hovav / Causativeverbsin English

someverbsdo not showit at all, and why someverbsshowit underrestricted circumstances . Finally, such an account must grapple with the issue of whetherthe data discussed in this sectionrepresenta unifiedphenomenon or not.

3. Towards an account of the alternation

The phenomenon we are dealing with falls under the general rubric of diathesis alternations, alternations which involve changes in the syntactic expression of the arguments of a predicator as well as in its adicity (the number of arguments it requires) . Therefore, our account of the alternation should ideally be embeddedin a generaltheory which accounts for the adicity of predicatesand the expressionof their arguments. We follow much current researchon the lexicon (Jackendoff 1990, Rappaport et al. 1988, Rappaport and Levin 1988, Hale and Keyser 1986, 1987; Pinker 1989, among others) in assuming that the properties of diathesis alternations in general can be predicted from the formulation of appropriate lexical semantic representations for the alternating verbs together with a set of linking rules (Carter 1988), rules which determine the syntactic expression of arguments of a predicate. As assumedin much of this literature, we postulate two levels of lexical representation. The first is a lexical semantic representation, a representation of the syntactically-relevant aspectsof verb meaning, which probably takes the form of a predicate decomposition. The second is a lexical syntactic representation or argument structure, which encodesthe syntactic expressionof the arguments of a verb. We assumethat the lexical syntactic . representationis derived from the lexical semantic representationby a set of linking rules. Since the causative alternation verbs can be found with either one or two arguments, a question which arises in the context of determining the lexical semantic representation of these verbs is whether they are basically one argument or two argument verbs. That is, are the causativeusesformed from the non-causative ones or vice versa? We assumethat the basic use of the verb will impose less stringent restrictions on its arguments than other uses since the conditions associatedwith a derived use might impose additional co~straints on the arguments of the verb. In those instanceswhere there are different selectionalrestrictions on the transitive and intransitive uses, the use with the looser selectional restrictions, if there is one, is the basic one. This means that given the data discussed above, for the verb buzz it is the

B. Levin, M. RappaportHovav / Causativeverbsin English

intransitive use that is basic, but for the verb peel it is the transitive use that is basic. The question to be asked in such instances is what aspect of verb meaning determines that peel is basically transitive, while buzz is basically intransitive. The selectionalrestriction criterion still leavesopen the issueof those verbs that appear to have similar selectionalrestrictions for both the transitive and intransitive uses, such as break or open. (Although given the comment in footnote 12, it is possible that for all verbs the selectional restrictions in one variant are looser than those in the other.) In order to isolate the meaning components which determine the (in )transitivity of a verb, we compare verbs like break that permit transitive and intransitive uses, to verbs such.as laugh, cry, or glitter that permit only intransitive uses (except perhaps under very special circumstances). (In section 6 we will address the issue of what distinguishes the break verbs from transitive verbs like cut and write, which have only transitive, but not intransitive , uses.) The question is what makes verbs like break on their intransitive use different from these other verbs? Here we draw on Smith' s ( 1970) insightful discussionof the semantic factors that playa part in determining which verbs that can be used intransitively have transitive causativeuses. Smith characterizesthe difference between those intransitive verbs which ' do and do not have transitive causativeusesby meansof a notion of external ' control . Verbs like break, Smith proposes, denote eventualitiesthat are under the control of some external causewhich typically brings such an eventuality about. Such intransitive verbs have transitive usesin which the external cause is expressedas subject. Verbs like laugh and cry do not have this property : ' ' the eventualities each one denotes ' cannot be externally controlled but can ' ' be control led only by the person engaging in it ; that is, control cannot be ' ' relinquished ( 1970: 107) . Smith takes the lack of a causativetransitive use for these verbs and other verbs such as shudder, blush, tremble, malinger, and hesitate, to be a reflection of the presenceof internal control ; we return in section 4 to the question of why verbs of internal control should have this property . (47a) (47b) (47c)

Mary shuddered. * The green monster shudderedMary . The green monster made Mary shudder.

: (35a-c (Smith1970

Similar distinctions have been recognized in other work on English (e.g ., Hale and Keyser 1987) and other languages (e.g ., Guerssel1986 on Berber ) .

B. Levin, M . Rappaport Hovav / Causativeverbsin English

For reasons which we explain below, we will not use Smith' s notion of 'control' for distinguishingamong intransitive verbs which do and do not have causativeuses. Rather, we use a related notion, distinguishing between' inter' ' ' nally and externally caused eventualities. With an intransitive verb denoting an internally causedeventuality, someproperty inherent to the argument of the verb is ' responsible' for bringing about the eventuality. On this approach, the concept of internal cause subsumesagency. For agentive verbs such as play , speak, or work, the inherent property responsiblefor the eventuality is the will or volition of the agent who performs the activity . However, an internally caused eventuality need not be agentive. For example, the verbs blush and tremble are not agentive, but they, nevertheless , can be consideredto denote internally causedeventualities, becausethese eventualities arise from internal properties of the arguments, typically an emotional reaction. 13 Verbs with an inanimate, clearly non-agentive subject, may also denote internally causedeventualitiesin the sensethat theseeventualitiesare possible becauseof inherent properties of their subjects. In particular , the notion of internal cause can be straightforwardly e~tended to encompass verbs of emission. It is an internal physical property of the argument of such a verb which brings about the eventuality denoted by the verb. This property is reflected in the strong restrictions that these verbs impose on possible subjects. For example, only very few things have the properties that are necessary to sparkle, and the same holds for other verbs of emission. Consistent with the classification of theseverbs as internally causedis the fact that , as mentioned in section 2, verbs of emission generally do not have causativecounterparts, as illustrated in (48) . (We return in section 7 to cases in which they do.) * (48a) The jeweller sparkled the diamond . ' * (48b ) Max glowed Jenny s face with excitement . * (48c) We buzzed the bee when we frightened it . * (48d ) The cook bubbled the stew. 13 The verbsshudder andshake , whichat first glanceappearto havethe samemeaning , present an interestingminimalpair. Only shake , and not shudder , showsa transitivecausativeuse. Our accountwouldsuggestthat shakingis externallycausedandshudderingis internallycaused . This . The proposalreceivessupportfrom an examinationof the thingsthat can shakeand shudder tw~ setsarenot co-extensive ; thesetof thingsthat shudderis to a largeextenta subsetof the set of thingsthat shake . Thingsthat shudderusuallycan be thoughtof as havinga ' self-controlled' include ; , animals , and, perhapsby forcedextension , the earth or a car. In body they people contrast, leaves , teacups , or furniture can only shake. This difference , like the internal versus externalcausedistinction, reflectsthe way weconceptualize the world.

B. Levin, M . Rappaport Bovav I Causativeverbsin English

Since verbs of emission pattern with other verbs without causative counterparts , we use the notion internal versusexternal causerather than the notion of control . It seems inappropriate to attribute control to the inanimate emitter argument of a verb of emission. In contrast to internally caused verbs, verbs which are externally caused inherently imply the existenceof an external cause with immediate control over bringing about the eventuality denoted by the verb: an agent, an instrument, a natural force, or a circumstance. Thus something breaks becauseof the existenceof some external cause; something does not break solely because of its own properties. Some of these verbs can be used intransitively without the expressionof an external cause, but , even when no cause is specified, our knowledge of the world tells us that the eventuality theseverbs denote could not have happenedwithout an external cause.

(49a) The vasebroke.j Antonia broke the vase. .jPat openedthe door. (49b) The door opened .We thus assume that the intransitive verbs which have transitive uses are externally caused, while those intransitive verbs which do not are internally caused. A closer look at the class of alternating verbs will bear out this suggestion. The change of state verbs that figure prominently among the alternating verbs describe changes in the physical shape or appearanceof some entity that can be brought about by an external cause, be it an agent, a natural force, or an instrument. Many of theseverbs are deadjectival; they are based on stage-level adjectives which describe properties of entities that can be caused to change, such as their physical characteristics, color , and temperature (Dixon 1982) . Some examples of such deadjectival verbs taken from Levin ( 1993) are given below in (SO); these verbs fall into two major groups, one in which the verbs are zero-related to adjectives, as in (a), and the second in which the verbs are formed from adjectivesthrough the use of the affix -en, as in (b) . ( 50a) brown , clear, clean, cool, crisp, dim , dirty , dry, dull , empty, even, finn , level, loose, mellow, muddy, narrow , open, pale, quiet, round , shut, slack, slim, slow, smooth, sober, sour, steady, tame, tan, tense, thin , warm, yellow, ... (SOb ) awaken, blacken, brighten, broaden, cheapen, coarsen, dampen, darken, deepen, fatten, flatten, freshen, gladden, harden, hasten,

B. Levin. M. RappaportHovav I Causativeverbsin English

heighten, lengthen, lessen, lighten, loosen, moisten, neaten, quicken, quieten, redden, ripen, roughen, sharpen, shorten, sicken, slacken, smarten, soften, steepen, stiffen, straighten, strengthen, sweeten, tauten, thicken, tighten, toughen, waken, weaken, whiten, widen, worsen, ... The verb smarten provides a particularly interesting illustration of the constraints on the adjectives that can serve as the base for verbs. Although the ' ' ' , intelligent and well and fashionably adjective smart has two senses ' dressed, the verb smarten is related to the second adjectival sense, reflecting the fact that it is typically only in this sensethat the adjective denotesa stagelevel property, and, hence, a property that might be causedto change. l4 That is, individual -level properties are typically not acquired as a result of an external cause, whereasstage-level properties are. The distinction between internally versus externally causedeventualities is not relevant only to verbs of change. l 5 It also explains the behavior of verbs of position with respect to the causative alternation. As noted above, verbs like hang, lean, sit , and stand have causative uses, but verbs like loom and slouchdo not. It seemsto us that the differencebetweeninternal and external cause is the key to their differing behavior. Looming and slouching are postures that are necessarilyinternal caused, unlike hanging, leaning, sitting, or standing, which are postures that can be brought about by an external cause. Many studiesassumethat the intransitive variant of a causativealternation verb is basic and the transitive variant derived. This assumption probably seemsjustified becausethe meaning of the transitive verb includes that of the 14

Betsy Ritter has pointed out to us the expressionSmarten up! Here the verb is related to the ' ' adjectival sense intelligent , but interestingly the verb is related to a stage-level use of the . It that this adjective appears adjective, like rnany other basically individual -level adjectives, can sornetirnesbe used as a stage-level predicate. Dowty ( 1979: 129, fn. 4) discusses other instancesin which deadjectival verbs lose sorneof the sensesof their baseadjective. For exarnple, he notes that although the adjective tough can rnean ' ' either ' difficult or ' resistant to tearing , the verb toughencannot rnean ' rnake difficult ' . We think that the stage-level versusindividual -level distinction could be responsiblefor at least sorneof the differencesin available sensesthat Dowty cites including the toughenexarnple. 15 There seernsto be a gap in the English verb inventory : there appear to be no agentive verbs of changeof state. We do not have an explanation for their absence. In fact, we are aware of very few internally causedverbs of changeof state at all , and those we have found , such asflower and blo.r.rom, and, in sorne languages, blush are non-agentive. We discuss this type of verb in Levin and Rappaport Hovav (to appear) .

B. Levin, M. RappaportBovavI Causative verbsin English

intransitive verb. For example, while transitive break means' causeto become broken' , intransitive break means ' become broken' . We suggest that this is not the case. A scrutiny of the range of verb classesin Levin ( 1993) reveals that there are no externally causedverbs without a transitive variant. That is, all externally causedverbs have a transitive causative use, but not all of them need have an intransitive use in which the external causeis unspecified(e.g., write or murder) . Given this generalization, we offer the following analysis: internally caused verbs are inherently monadic predicates, and externally causedverbs are inherently dyadic predicates, taking as arguments both the external cause and the passive participant , which is often referred to as the patient or theme. The adicity of the predicate is then a direct reflection of a semantic property of the verb. Externally caused verbs only detransitivize under specific circumstances; we discuss the circumstances that license the non-expressionof the causeargument of externally causedverbs in section 6. But it is important to stress that on our analysis externally causedverbs do not undergo a processof causativization - they are inherently causative- but rather a processof detransitivization. Since the majority of causativealternation verbs are externally caused, it is the processof detransitivization that is most pervasive in English. The following lexical semantic representationsfor the two types of verbs reflect the type of distinction we suggest. BROKEN ]] ( 51) break-transitive: [x CAUSE [y BECOME ( 52) laugh: [x LAUGH ] The representation for a verb like break is a complex lexical semantic ; it represents the meaning of representation involving the predicate CAUSE such verbs as involving two subevents, with each of the argumentsof the verb associated with a distinct subevent. The representation for an internally caused verb such as laugh does not involve the predicate CAUSE ; such verbs have only one subeventand are taken to be basically monadic. We discussthe rules that determine the syntactic expressionof the arguments in theselexical in the next section. However, it is clear that the semantic representations ' intransitive fo rm of break involves an operation which prevents the external cause from being projected to the lexical syntactic representation (the argument structure) . We do not discussthis operation in this paper, but seeLevin and Rappaport Hovav (to appear) for discussion. In light of the discussion above, certain facts about the formation of causativesacross languagescited by Nedjalkov ( 1969) are not surprising. In

verbsin English B. Levin, M. RappaportHovavI Causative

this study, which is basedon a survey of 60 languages, Nedjalkov looks at the morphological relation between the causative and non-causative uses of the verbs break and laugh (as well as two other verbs) in each of theselanguages. Nedjalkov points out that in the majority of his sample, the transitive causative form of the verb break is morphologically unmarked, with the intransitive form being identical to the transitive form ( 19 out of 60 languages ) or derived from this form (22 out of 60 languages). If verbs such as break are appropriatelycharacterizedas denoting externallycausedeventualities , then the monadic use is in some sensederived and indeed morphological marking has a function : it is needed to indicate the non-expression of the external cause. 16 Nedjalkov also considers the verb laugh. As a monadic verb which is internally caused, the verb laugh does not denote an eventuality that involves an external cause and can, therefore, be assumed to be basically a single argument verb. lit fact, Nedjalkov does not cite any languagesin which this verb has a transitive counterpart which is identical in form to or morpho logically less complex than the intransitive and which receives a causative 17 interpretation . Nedjalkov reports that in .54 of the 60 languagessurveyed, the causative form is morphologically more complex than the non-causative form ; seealso Hale and Keyser ( 1987) for discussionof some similar data. ' Haspelmath ( 1993) follows up on Nedjalkov s study and discusses verbs which tend not to show consistent patterns cross-linguistically . For example, verbs corresponding to English melt tend to be basically transitive in most languages, with the intransitive form being the derived form , but the opposite pattern is found in a few languages. It is likely that this variability arises becausethe meaning of a verb such as melt is consistent with classification as either internally or externally caused. 18 Pinker ( 1989) also points out that 16 Of course a is usedto create wherethereverse , therearesomelanguages typeof morphology 's in Nedjalkov . 9 of the60languages fromthemonadic sample predicate dyadiccausative predicate 's themorpheme . However showthisproperty , it is difficultto tell fromNedjalkov paperwhether in thelanguages in general of causatives breakisthatusedfor thederivation usedto formtransitive thatin the to hispapersuggests citesin theappendix concerned , althoughthedataNedjalkov . the causative of used to form the it is at least not the of laugh morpheme languages majority 17 Nedjalkov and wheretheverblaughhasbothtransitive ( 1969 ) notesthatin thoselanguages ' ' ' intransitive uses , this verbis likelyto mean'laughat ratherthan makelaugh whenused . transitively 18 Nedjalkov , burnandboil, findingthat theirbehavior ) alsolooksat two otherverbs (1969 thanthatof break wasmuchmorevariable formation across to causative withrespect languages withtheverbmelt, could observes . Thisvariation andlaugh . likethevariationthatHaspelmath . classification of theseverbs alsobeattributedto thevariable

B. Levin. M. RappaportBovavI Causative verbsin English

there are certain classesof verbs which denote eventualities which can be construed on cognitive grounds to be either internally or externally caused. It is precisely with respect to these kinds of verbs that cross-linguistic variation is expected. In fact, appropriately formulated linking rules should predict which kinds of verbs are most likely to exhibit cross-linguistic variation . The distinction betweeninternal and external causation seemsto do just this, and we take it to corroborate our approach.

4. Formulatingthe linking rules Although the number of arguments that a verb requires in its lexical semantic representationis determined by whether it describesan internally or an externally causedeventuality, we must also posit linking rules that ensure that these arguments have the appropriate syntactic expression. As we describein Rappaport et al. ( 1988), we seelinking rules as creating the lexical syntactic representation or argument structure of a verb from its lexical ' semantic representation. As we also outline in that paper, a verb s argument structure in turn relatively straightforwardly determines the d-structure syntactic configuration that the verb is found in. We propose that the following linking rules are among those that determine the lexical syntactic representation of a verb: (53) Immediate CauseLinking Rule: The argument of a verb that denotes the immediate cause of the eventuality denoted by that verb is its external argument. ( 54) Directed ChangeLinking Rule: The argument of a verb that denotes an entity undergoing a directed changedenoted by the verb is its direct internal argument. We have stated theselinking rules in tenDs of the argument structure notions ' ' ' ' external argument and direct internal argument ; these argument structure ' ' positions are then projected into syntax as the d-structure grammatical relations of subject and object, respectively. In the next section we explain why we have stated these rules in tenDS of argument structure notions that correspond most closely to d-structure grammatical relations rather than to sstructure grammatical relations. In this section we discuss the linking rules and their application to the data we have discussed.

B. Levin, M . Rappaport Hovav I Causativeverbsin

Englisll

The Immediate Cause Linking Rule is intended to apply to the argument that causesthe eventuality denoted by both internally and externally caused verbs. First , we consider internally caused verbs such as laugh or play . The verb laugh' s single argument is the cause of the eventuality that the verb denotes and will be expressedas an external argument as a consequenceof the Immediate Cause Linking Rule. This rule will also explain why laugh and other internally caused verbs do not have a simple transitive causative use. Such a use would involve the introduction of an additional cause, external to the eventuality denoted by the verb. Such an external causewould have to be expressedas the external argument due to the Immediate Cause Linking Rule. The external causewould thus compete with the verb' s own argument for external argument. As a verb has only a single external argument, such causative useswould be ruled out. On this account, the lack of a causative variant for an internally caused verb receivesan explanation in terms of the properties of argument structure; this explanation only indirectly appeals to the semanticsof the verbs involved. 19 The only way to introduce an external causeis to expressthe causative use of internally caused verbs periphrastically. And across languages, verbs like laugh, cry, speak or play are causativized through the use of a causative affix or verb. ( 55a) (55b) (56a) (56b) ( 57a) ( 57b) (58a) ( 58b)

* The clown

laughed me. The clown made me laugh. * The bad news cried me. The bad news made me cry . * The director spoke the actor. The director made the actor speak. * The parents played the children. The parents made the children play .

Following Baker ( 1988), Marantz ( 1984), S. Rosen ( 1989), and others, we assumethat the causative morpheme or verb comes with its own argument structure, so that the Immediate Cause Linking Rule does not have to 19 Pinker ( 1989 ) points out that internally causedverbs are not expectedto have causativeuses becausethe eventuality they denote cannot have an external causewhich is at the same time an immediate cause; that is, such eventualities cannot be construed as being directly caused. Although this property is probably implicated in the non- causativizability of such verbs, the existenceof ii1;ternally causedverbs which do causativizeunder certain syntactic conditions, such as those discussedin section 8, suggeststhat syntactic factors enter into the explanation as well.

verbsin English B. Levin. M. RappaportBovav/ Causative

associate two arguments from a single argument structure with the same argument structure position . General principles will determine that in languages with causativeaffixes or verbs the introduced causewill be first in line for being chosen as the external argument in its clause. The Directed Change Linking Rule is similar in spirit to familiar linking rules which associatea patient or a theme (or an equivalent notion ) with the direct object grammatical function (Anderson 1977, Fillmore 1968, Marantz 1984, among others) . Our formulation is meant to give specific semantic content to the notions ' patient' and ' theme' . The Directed Change Linking Rule is meant to apply to verbs of change of state and verbs of change of location. This second class includes verbs of directed motion such as come, go, rise, andfa // but NOTverbs of manner of motion such as roll , run, jog , and bounce. This difference follows because, although the action denoted by a verb of manner of motion inherently involves a kind of change, it is not a directed change. Tenny suggeststhat there are certain kinds of changeswhich can be characterized ' ... as a change in a single parameter or a change on a scale' ( 1987: 189) . We call such changes' directed changes'. Tenny. arguesthat an argument denoting an entity which is specifiedto undergo such a changeis realized in the syntax as a direct object. This property distinguishes a change of state verb like dry from both agentiveand non-agentive verbs of manner of motion like walk and roll . The verb dry specifiesa change characterizable in tenDS of a single parameter, dryness, whereas walk and roll do not specify such a change. In contrast, for verbs of directed motion there IS a directed 2o change: a movement in a particular direction. The argument of a nonagentive manner of motion verb such as roll will be a direct internal argument, as we will see, but this linking will be effected by another linking rule. The justification for this will be given in section 7. The linking rules we have formulated also ensure that when a verb like break is used transitively, the external cause will be the external argument, and the patient, since it undergoes a specified change, will be the direct internal argument. When a verb like break is used intransitively with only the patient argument, the Directed Change Linking Rule will apply, and this 10 As fonnulatedherethe DirectedChangeLinking Rule, unlikesomeother proposedlinking rulesthat aresimilarin scope , suchas widenor cool. , will applyto certainatelicverbsof change We arguethat this propertyis desirablein Levin and RappaportHovav (to appear ), wherewe Rule with other a more detailed of the Directed linking comparison ChangeLinking provide rules, especiallythosewhichmakereferenceto conceptssuchas telicity. We alsocompareour ' ) which makesuseof the rather similar notion of approachwith one such as Dowty s ( 1991 ' incrementaltheme'.

B. Levin, M . Rappaport Hovav I Causativeverbsin English

. argument will be the direct internal argument. Since these verbs have sstructure subjects when intransitive , this argument must assumethe subject grammatical relation at s-structure, presumably as a consequenceof independent syntactic principles. The typical GB -framework account of the expression of the arguments of such verbs makes reference to the Case Filter , Durzio' s Generalization, and the Extended Projection Principle (e.g., Burzio 1986); we do not go into details here. 21 Together the Immediate Cause and Directed Change Linking Rules can be used to predict whether the membersof the verb classesthat we discussedin section2 will have causativeusesor not. Verbs of changeof state are inherently dyadic verbs, so they will always have causativeuses, although not as a result of causativization; in section 6 we elaborate on the circumstancesin which these verbs can have monadic ' detransitive' uses. Internally caused verbs are not expectedto have causativeuses, explaining the behavior we observedfor verbs of emission; we discuss in section 7 why some verbs of emission neverthelessdo have causatives. Agentive verbs of manner of motion , as internally causedverbs, are also not expected~o have causativeuses. As seenin section 2 these verbs do not typically have causative uses in isolation; we discussin section 8 why theseverbs may have causativeusesin the presenceof a directional phrase. We attribute the mixed behavior of verbs of position to a split in the class: some of theseverbs are internally causedand others are not , and the internally causedverbs are not expectedto have a causativeuse. These linking rules leave open the question of what happens with an argument that falls under neither of the linking rules introduced in this section. Here we make the assumption, which we justify in Levin and Rappaport Hovav (to appear), that an argument that is not linked by one of these two linking rules will be a direct internal argument rather than an external argument.22 ( 59) Default Linking Rule: An argument of a verb that does not fall under the scopeof the other linking rules is its direct internal argument. 21 SeeBresnanand Zaenen( 1990 ) for an accountwithin LFG. 22 In Levinand RappaportHovav(to andexistence ), wearguethat verbsof appearance appear requiretheir own linking rule. We formulatean additionalrule that appliesto theseverbs, linking the argumentwhoseexistence is asserted to directinternalargument . The DefaultLinking Ruleis supposedto apply to thoseargumentsthat do not fall under the scopeof any linking rule, whetherit is this additionallinking rule or the previouslyfonnulatedrules, the ImmediateCause and DirectedChangeLinking Rules.

verbsin English B. Levin, M. RappaportHovavI Causative

The Default Linking Rule will apply to the theme (located) argument of transitive sit , stand and other externally caused verbs of position, since this argument neither causes the eventuality denoted by the verb nor does it 23 undergo a specified change. We return to the Default Linking Rule in sections7 and 8, where we illustrate its applicability more fully .

5. The Un8ccaativeHypothesis We have introduced a distinction between internally and externally caused eventualities. As we discussin greaterdetail in Levin and Rappaport Hovav (to appear), the two classesof intransitive verbs describedhere are preciselythose that are implicated in phenomenawhich fall under the rubric of the Unaccusative Hypothesis ( perlmutter 1978). Since the linking rules do not make referenceto the adicity of a predicate, they predict that a verb like break, even when the external causeis not expressed , still takes a direct internal argument, as can be seenfrom the application of the linking rules to the representations we introduced above for the two classesof intransitive verbs. With intransitive break, only the y variable in (51) is expressed ; as the argument undergoing a directed change, it will be a direct internal argument, and hencead -structure object in the syntax. In contrast, the x variable in (52), as an immediate cause, will be an external argument, and hencea d-structure subjectin the syntax. The syntactic expressionof the argumentsof thesetwo verbs is given below.

-intransitive : - [vpV NP] (60a) break NP : 60b ( ) laugh [vpV] Given the definitions of unaccusativeverbs as verbs taking a single direct internal argument and unergative verbs as verbs taking a single external argument, the linking rules proposed in section 4 will receivesupport if there is evidencethat internally caused verbs are unergative and externally caused . tive diagnostics . tive. We review two uoa(x:usa verbs, when monadic, are una(x:usa ; see Levin and discussion this claim for further be used to that can ; support Rappaport Hovav (to appear) . 23 Wedo notdiscuss of of theapplication theseverbsfurtherin thispapersincea full account in their the linkingrulesto theseverbswouldrequireus to introducecertaincomplications Hovav(to appear in LevinandRappaport . Wediscuss thesecomplexities behavior , ). However verbsof position caused thattheexternally wewouldliketo pointout thatouraccount suggests . transitive shouldbebasically

B. Levin, M . Rappaport Hovav / Causativeverbsin English

Work on the Unaccusative Hypothesis has establishedthat the resultative construction can be used as an unaccusativediagnostic (Hoekstra 1984, Levin and Rappaport Hovav (to appear), Simpson 1983, among others) . Although both unaccusativeand unergative verbs are found in this construction, they pattern differently due to an interaction of verb type with a syntactic constraint requiring the resultative phrase to be predicated of ad -structure object. What matters for our purposes is that when an unaccusativeverb is found in the resultative construction, the resultative phrase is predicated directly of its surface subject, as in (61), but a resultative phrase cannot be predicateddirectly of the surface subject of an unergative verbs, as in (62a). A resultative phrase may only be predicated of the subject of an unergative verb ' ' through the mediation of what Simpson ( 1983) calls a fake reflexive object, as in (62b). Alternatively , a resultative phrase may be predicated of a nonsubcategorizedobject found with an unergative verb, as in (63), an option not available to unaccusativeverbs, as shown in (64) . 24

(61) (62a) (62b) (63) (64)

The bag broke open. *We yelledhoarse. We yelledourselveshoarse. The dog barkedthemawake. *The bag broke the groceriesall over the floor.

Thus the different patterns of the resultative construction correlate with the status of a verb as unaccusativeor unergative: a monadic verb which allows a resultative phrase to be predicated directly of its subject is unaccusative, while a monadic verb which allows such a phrase to be predicated of an object - either a ' fake' reflexive or a non-subcategorizedobject - is unergative. The closely related X ' s way construction is also an unaccusativediagnostic. This construction, in which a resultative phrase is predicated of the subject of a verb through the use of the phrase ' X ' s way' in object position, is found with unergative. verbs, but not with unaccusative verbs (Jackendoff 1990, Marantz 1992) .

(65) They workedtheir way to the top. (66) *The Arctic explorersfroze their way to fame. 24 SeeLevin and Rappaport Hovav (to appear) for an explanation of the differential behavior of the two classesof verbs in the resultative construction, and Hoekstra ( 1992) f~r an alternative account.

B. Levin, M . Rappaport Hovav / Causativeverbsin English

The resultative and X 's way constructions distinguish internally caused verbs from externally causedverbs as predicted. An examination of the set of tokens of theseconstructions we have collected over the last few years shows that internally causedverbs like laugh, play , and work are regularly found in the X 's way construction and the unergative resultative pattern, while instances of monadic externally caused verbs are attested only in the unaccusative resultative pattern. The behavior of verbs of emission in the resultative construction is of particular interest since the classification of these verbs has been the subject of controversy. Perlmutter ( 1978) originally classifiedtheseverbs as unaccusative , but this classification has been challenged (see for example Zaenen 1993) . We have classified these verbs as internally caused verbs, and hence, we predict that they will pattern with unergative verbs in general, and in the resultative and X 's way constructions in particular . The examples below verify this prediction . 25

(67a) The beaconsflared the newsthrough the land. (HendersonI 92;

cited in K.-G. Lindkvist, A Comprehensive Study of Conceptions of , 1976, p. 89, sec. Locality, Almqvist & Wiksell, Stockholm, Sweden 233, 4) ' (67b) ... you cant just let the thing ring itself to death, can you? (Observer ; TraceThat Call No More!, New York Times, March 8, 1989 ) (67c) The very word was like a bell that tolled me back to childhood summers... (Hers; Child' s Play, Women's Sway, New York Times, July 17, 1988) (67d) Then he watchedas it gurgledits way into a whiskeytumbler. (M. Grimes, TheFive Bellsand Bladestone , Little, Brown, Boston, 1987, . 200 ) p (67e) To counterthe uneasethat was oozing its way betweenthem. (P. Chute, Castine , Doubleday, GardenCity, NY , 1987, p. 214) In Levin and Rappaport Hovav (to appear) we look at a wide range of tests and find that they corroborate the results of the two tests that we have discussedin this section, further supporting the linking rules formulated in 25 Given their unergative classification. we would not expect these verbs to pattern as unaccusativeverbs with respectto the resultative construction. In actual fact. some of theseverbs are found in the unaccusativeresultative construction. but as we discussin Levin and Rappaport Hovav (to appear) their unaccusative behavior correlates with a shift in meaning. with the additional meaning being one that is typically associatedwith an unaccusativeclassification.

B. Levin, M . Rappaport Hovav I Causativeverbsin English

section 4. In that work , we also show that there are some verbs which are compatible with both internal and external causation. Theseverbs include the non-agentive verbs of manner of motion such as roll and bounce and the verbs of position . As we show in that work , with such verbs external causation is correlated with unaccusative status, while internal causation is correlated with unergative status.

6. When can an externally causedverb detransitivize? The next question we addressis the following : if externally causedeventualities are basically dyadic, when can verbs denoting such eventualities turn up as intransitive , and why is this possibility open to some verbs only for ' certain choices of arguments? Again we draw on the insights in Smith s ( 1970) paper to reach an understanding of this phenomenon. In trying to identify the factors that permit detransitivization (that is, the non-expressionof the external cause), it is useful to look at the characteristics . of the subjects of externally caused verbs. Among the verbs that never detransitivize are verbs that require an animate intentional and volitional agent as subject, such as the verbs murder and assassinateor the verbs of creation write and build. / murdered the candidate. (68) The terrorist assassinated wrote a letter to the editor of the local newspaper. 69a ( ) Tony (69b) That architect also built the new high school. Smith proposesthat the verbs of change that may be used intransitively are ' precisely those in which the change can come about independently in the ' sensethat it can occur without an external agent ( 1970: 102) . She identifies independenceand external control - the notion which we have subsumed under our notion external cause - as the two features which characterize verbs of change. Independence allows for the possibility of intransitive counterparts, and external control or causation allows for the possibility of a ' transitive causativeuse. Smith s observation can also be recast as follows : the transitive verbs that detransitivize are those in which the eventuality can happen spontaneously without the volitional intervention of an agent. We believe that this property is reflected in the ability of such verbs to allow natural forces or causes, as well as agents or instruments, as external. causes, and, hence, as subjects, as illustrated with the alternating verb break.

B. Levin, M. RappaportHovav/ Causative verbsin English ( 70) The vandals / the rocks / the stonn broke the windows .

Verbs such as break contrast with verbs such as murder, assassinate , write. and build. These four verbs, as well as any other verbs which, like them, denote eventualities that require the participation of a volitional agent and do not admit natural force subjects, will not detransitivize, despite the fact that their meaningsinvolve a notion of ' cause'.

(7]a) (7] b) (7]c)

*The candidateassassinated / murdered. *The letter wrote. *The housebuilt.

In fact , these four verbs are among those that require an agent in the strongest sense: they do not even allow an instrument as subject .

thecandidate . (72a) *Theknifeassassinated /murdered (72b) *Thepenwrotetheletter. cranebuilt thehouse . (72c) 11The A verb like cut shows that the set of verbs that do not detransitivize is not limited to verbs which restrict their subjects to volitional agents. Although this .verb does not typically allow natural force subjects, it does allow instruments in addition to agents as subjects. 26

(73) The baker/that knife cut the bread. Sentence(74), however, cannot be used to describe the bringing about of a separation in the material integrity of some object. ' ' (74) * The bread cut. (on the interpretation The bread came to be cut ) The behavior of a verb like cut can receive an explanation. Its meaning includes a specification of the means involved in bringing the action it denotes about, which in turn implies the existence of a volitional agent. Specifically, the very meaning of the verb cut implies the existenceof a sharp instrument that must be used by a volitional agent to bring about the change 26 SeeBrousseauand Ritter ( 1991) for further discussionof the circumstancesthat allow verbs to take both instruments and agents as subjects.

B. Levin, M . Rappaport Bovav / Causativeverbs"in English

of state denoted by the verb. If the samechange of state were to come about without the use of a sharp instrument, then it could not be said to have come about through cutting , showing that the choice of instrument makes cutting cutting . Perhaps the same considerations can explain the behavior of the verb remove, which does not have an intransitive form . Its non-existence might seemsomewhat surprising since at a first approximation this verb' s meaning ' ' might be paraphrased as cause to become not at some location . A closer look at the verb remove's meaning reveals that the eventuality it denotes is brought about by a volitional agent, as shown by the oddnessof the examples in (75), which have inanimate non-volitional subjects. (75a) ??The wind removed the clouds from the sky. (cf. The wind cleared the clouds from the sky.) (75b) ??The water removed the sand from the rocks. (cf. The water washed the sand from the rocks.) We assume that the same factors explain why most morphologically complex verbs formed with the suffixes -ize and -iff cannot typically detransitivize, as the data repeatedhere illustrates.

(76a) The fanner homogenized/pasteurizedthe milk . (76b) * The milk homogenized/pasteurized. (77a) Carla humidified her apartment. (77b) * Her apartment humidified. Most of theseverbs cannot detransitivize, we propose, becausethey describe eventualities such as being pasteurized or homogenized that cannot come about spontaneouslywithout the external intervention of an agent. It appears to be preciselythose -ify and -ize verbs which allow for this possibility that do detransitivize. (78a) I solidified the mixture./ The mixture solidified. (78b) The cook caramelizedthe sugar./ The sugar caramelized. Again , the -iff and -ize verbs that do and do not permit intransitive uses contrast ,with respectto the range of subjectsthey permit when transitive. The verbs that resist detransitivization show a narrower range of subjects when transitive ; specifically, they appear to exclude natural force subjects.

B. Levin, M . Rappapor ' Hollall I CausativelIerbsin English

(79a) * The rainy weather humidified the apartment. (79b) The intense heat caramelizedthe sugar. If we look more closely at some of the alternating verbs in -iff and -ize listed in (80), we see that many of these verbs, such as intensify or equalize, are deadjectival and are very similar in meaning to the previously mentioned alternating deadjectival verbs in (50) . (80a) acetify, acidify , alkalify , calcify, carbonify , emulsify, gasify, intensify, lignify , liquefy, nitrify , ossify, petrify , putrefy, silicify, solidify, stratify, vitrify , ... (80b) caramelize, carbonize, crystallize, decentralize, demagnetize, depressurize , destabilize, equalize, fossilize, gelatinize, glutenize, harmonize, ionize, magnetize, neutralize, oxidize, polarize, pulverize, regularize, staQilize, vaporize, ... Other alternating -iff and -ize verbs are denominal; their meaning may be ' paraphrasedroughly as causeto turn into the substancenamed by the noun that the verb is based on' : caramel for caramelize, powder for pulverize, gas for gasify, and so on. The non-alternating -iff and -ize verbs also include some denominal verbs whose stems are nouns that name substances: zincify , carbonize, and lodize. But -what is interesting is that the meaning of these non-alternating verbs is different from that of the alternating verbs: it could be paraphrased as ' ' ' process or treat using the substance rather than cause to turn into the ' substance. We suggest that due to this difference in meaning, these verbs require an agent and hence do not detransitivize. In fact, if zincify meant ' turn to zinc' rather than ' ' processwith zinc , we would predict that the verb could alternate, and our own intuitions , as well as those of others we have consulted, is that it would. A preliminary examination of a wider range of non-alternating -iff and -ize verbs suggeststhat many describe changesthat involve a particular type of processing or treatment, as with the previously cited verbs homogenize and pasteurize or as with the verbs sterilize or vulcanize. Other non-alternating verbs involve changesof state that only come about through the active intervention of an agent, such as legalizeor sanctify. The constraint on detransitivization also explains why some verbs have intransitive usesonly for certain choicesof patient : it is only for thesechoices of patient that the change can come about without the intervention of an agent. For instance, in section 2 we noted the following contrasts involving the verb clear:

inEnglish verbs Hovav B. Levin , M. Rappaport I Causative (8Ia) (81b) (82a) (82b)

The menclearedthe table/ the sidewalk. *The table/ the sidewalkcleared. The wind cleared(up) the sky. The sky cleared(up).

Our knowledge of the world tell us that tables and sidewalks are things that are cleared (of dishes and snow, respectively) through the intervention of an animate agent. The sky, however, can clear through the intervention of natural forces, such as the wind . Thus the difference in the possibility of intransitive counterparts. Similarly, peeling - causing an entity to lose an outer layer is typically brought about through the actions of a volitional agent, particularly if a fruit or vegetable is involved. However, there are certain entities that lose their outer layers due to natural causesrather than through the action of an agent, and in these instancesthe verb peel can be used intransitively , as in the case of the loss of skin from a person, as illustrated in (84) .

(83a) (83b) (84a) (84b)

I peeledthe orange. . The orangepeeled . 'II peeledmy nose. My nosewaspeeling.

The verblengthencanbe usedto presentanothercontrastof the sametype: (85a) (85b) (86a) (86b)

The dressmaker lengthenedthe skirt. *The skirt lengthened . The mad scientistlengthenedthe days. . The dayslengthened

Typically skirts are only lengthenedthrough the intervention of an agent, and 27 hence the verb lengthen as applied to skirts is not found intransitively . Days, on the other hand, become longer as the earth progresses through a certain part of its orbit around the sun, something that happens without the intervention of an outside agent. And lengthenas applied to days is typically used intransitively, although in a science fiction context where artificial Z7 Of course, it is possible to construct contexts in which a skirt might be lengthenedby being washed. As Mary Laughren has pointed out to us, the intransitive use should be possible in such circumstances.

B. Levin, M . Rappaport Hovav / Causativeverbsin English

manipulation of the length of days is possible, transitive usesare also found , as in (86a) . These examplesshow yet again that detransitivization is possible precisely where an externally causedeventuality can come about without the intervention of an agent. In this sense, detransitivization is a productive process, since it appearsto be possible wherever this condition is met. In trying to pin down a verb' s transitivity , we have suggestedthat verbs can be categorized according to whether or not they denote an eventuality with an external cause and according to whether or not they denote an eventuality which can occur spontaneously. Since these two distinctions are rather similar, we might ask whether there is any need to distinguish between them. In fact, Haspelmath ( 1993) has independently developed an analysis similar to the one we present here, except that he does not make a clear distinction between the two notions. Although Haspelmath is not explicit about this, it appears that he takes the likelihood of spontaneousoccurrence ' for an event to be the opposite of external causation for that event. It seems to us that there is evidence favoring our approach, which takes the two notions to be distinct. Haspelmath links the likelihood of spontaneous occurrenceto intransitivity , without distinguishing betweenunaccusativeand unergative intransitive verbs as we do. For Haspelmath, those verbs which denote events which are likely to occur spontaneously will have an intransitive form , while those which are not likely to occur spontaneously will have only .a transitive form . However, Haspelmath does note that acrosslanguages certain intransitive verbs like break tend to be the morphologically marked member of a causative alternation pair of verbs, while others like laugh tend to be the morphologically unmarked member. It turns out , as he notes, that those verbs which, like break, are both spontaneously occurring and externally caused, are the ones which tend to have the intransitive form as the morphologically marked one. Those which, like laugh, are spontaneously occurring and internally caused tend to have the transitive member of a causative alternation pair morphologically marked. This difference justifies the retention of both notions. In some sense, Haspelmath' s study provides cross-linguistic corroboration of the results we obtained from the in -depth study of a single language.

7. Why can some intern aBy caused verbs have a causative use?

We now return briefly to the question of why some internally causedverbs sometimeshave causative uses. For instance, in section 2 we discussedhow

B. Levin, M . Rappaport Hovav I Causativeverbsin English

the verbs burp and buzz, which we have seen are internally caused, can be used transitively for certain types of arguments, as in the examplesbelow.

(87a) (87b) (88a) (88b)

The nurseburpedthe baby. *The nurseburpedthe doctor. (Smith1970 : (36a,c The postmanbuzzedthe bell. *The postmanbuzzedthe bees.

This phenomenonis sparselyand unevenly distributed acrossthe English verb inventory . For instance, the verb burp may be the only bodily process verb with a causative transitive use. The existenceof causative transitive uses is somewhat more widely attested with verbs of emission, particularly verbs of sound emission. This property might be attributable to the fact that , unlike verbs of bodily process, verbs of emission are typically predicated of inanimates ; therefore, some verbs of emission can describe either internally or externally causedeventualities. Among the verbs of emission that can be used transitively are a few verbs of light emission, including beam and shine, and a somewhat larger number of verbs of sound emission, including buzz, jingle , ring, and rustle. The verb buzz describesa type of sound that is emitted by certain animals - bees - or by certain types of devices- bells and buzzers. This verb can only be used transitively when the emitter of the sound is a device, and only if the device can be causedto emit the sound through direct manipulation by an external cause. Similarly , the verb of light emission beam may be used transitively when the object of the verb is a flashlight, again a ' 28 manipulatable device, but not a person s face. (89a) He beamedthe flashlight in the dark . (89b) * He beamedher face with satisfaction. The following generalization appears to hold of all the verbs of emission with causative transitive uses: they can be used transitively only with an emitter that is directly manipulated by an external cause, and when used in this way, the interpretation must be one in which the emission is directly brought about by an external cause. There are fewer verbs of light emission 28 StevePinkerhaspointedout to us that the transitiveuseof verbsof light emissiongenerally ' hasa meaningwhich includes' aimingin a particulardirection, renderinga directionalphrase that . He suggests perhapsthe analysisof these eitherobligatorily presentor at leastunderstood verbsshouldbe similar to the one we proposefor the causativeformsof the agentiveverbsof mannerof motionin the nextsection.

B. Levin, M. RappaportHovavI Causative verbsin English

with transitive causative usesthan there are verbs of sound emission since in most instances the entities of which verbs of light emission are predicated emit light without the intervention of an external cause, unless theseentities are devices. More verbs of sound emission than verbs of light emission are predicated of entities which emit a sound only under manipulation by an external cause. Some verbs of emission, such as sparkle and burble cited in section 2, never have causative transitive uses. It is unclear to us at this point whether some verbs of emission lack causative uses because they denote eventualities in which causation simply cannot be assumed by an external cause - that is, they are necessarily internally caused - or because, even though external causation may be possible, the set of verbs denoting eventualities compatible with both internal and external causation is explicitly learned from examples. We can now propose an explanation for why burp is apparently the only verb denoting a bodily processwith a transitive causative use. One of the few feasible instances of external causation of a bodily process is burping as it applies to babies. Babies are incapable of burping by themselves, so that the person caring for the baby must assumecontrol of the burping . Thus the verb burp can be used transitively only when babies are involved. We propose then that the eventualities denoted by a small number of English verbs are compatible with either internal or external causation, giving rise to both an intransitive use and a transitive causative use of these verbs. Sincethe causativeuse, when available, is associatedwith direct manipulation of the emitter by an external cause, we assume that in such instances the emitter is no longer viewed as the causeof the eventuality, and that the only cause is the external cause which manipulates the emitter. The Immediate Cause Linking Rule will apply to the external cause, so that it will be the external argument. The Default Linking Rule will apply to the emitter, since it does not meet the conditions on the other linking rules, and it will be the direct internal argument. As mentioned earlier, certain verbs of manner of motion have meanings compatible with either internal or external causation. These verbs include the set of verbs of manner of motion which are not necessarilyagentive, such as swing, bounce, or roll . In Levin and Rappaport Hovav (to appear) we provide evidence that a verb like roll is in fact unaccusativewhen predicated of an inanimate entity, as in The ball rolled ( on the floor ) , but unergative when used agentively, as in The dog rolled ( on thefloor ) . This behavior is just what our analysis predicts. When internal causation is involved, the Immediate Cause Linking Rule will ensure that the single argument, as the internal

verbsin English B. Levin. M. RappaportHovavI Causative

cause, will be the external argument, and the verb will be unergative. When external causation by an agent or a force, such as a push or gravity, is involved but no overt cause is expressed, the single argument will be the direct internal argument due to the Default Linking Rule, and the verb will be unaccusative. (The Directed Change Linking Rule does not apply since there is no directed change; the verb roll is atelic in the absence of a directional phrase.)

8. The interaction of directional phrasesand tr88itivity In this section we return to the last type of causatives rnentioned in the survey in section 2: the causativeusesof agentive verbs of rnanner of rnotion such as march and jump , illustrated in exarnples( I Sb) and ( 16b), which are repeatedbelow. (90a) The general rnarched the soldiers to the tents. (90b) The rider jumped the horse over the fence. These verbs are internally caused monadic predicates. By the linking rules, their single argument should be an external argument; therefore, contrary to fact, these verbs are not expected on our analysis to have the transitive causativeuseswhich some of them do manifest. In this section we provide an account of why some members of this set of internally caused verbs have causativeuses. In the process, we will also provide an answer to another question that is posed by the linking rules that figure in our account of causatives. We have formulated two linking rules which associatearguments with the notion of direct internal argument, and one which associatesarguments with the notion of external argument. Since one of the rules linking arguments to direct internal argument is a default rule, a natural question to ask is why we need the other rule that links arguments to direct internal argument, the Directed ' Change Linking Rule, at all. Couldn t the Default Linking Rule alone yield the same results? For example, if we dispensed with the Directed Change Linking Rule, the Default Linking Rule could be applied to the verb break with the desired result. This section explains why both linking rules are needed. We illustrate the necessityof the Directed Change Linking Rule using the behavior of agentive verbs of manner of motion with respectto causativization.

B. Levin, M . Rappaport Hovav / Causativeverbsin English

We propose that the key to understanding the unexpectedbehavior of the agentiveverbs of manner of motion is the fact that in English, such verbs can be used as verbs of directed motion in the presenceof a directional phrase ( Talmy ] 975, ] 985, among others) . (9Ia ) The soldiers marched to the tents. (91b) The horsejumped over the fence. When an agentive verb of manner of motion is used in a directed motion sense, then both the Immediate CauseLinking Rule and the Directed Change Linking Rule are applicable to the agentive argument. If we assumethat the Directed Change Linking Rule takes precedenceover the Immediate Cause Linking Rule - something that a default linking rule could by definition not do - then the single argument of a verb like run would be a direct internal argument when the verb is usedin a directed motion sense. And indeed many studies of unaccusativity have established that English agentive verbs of manner of motion are unaccusativein the presenceof a directional phrase. 29 Given the unaccusativityof theseverbs with directional phrases, it is possible to give an explanation for why agentiveverbs of manner of motion may have a transitive causative use when they are unaccusative: there is no external argument, so that the external causecan be linked to external argument. Since this alternative linking, which allows us to explain the existenceof the causative use of these verbs, cannot be accomplished by a default rule, we do not dispensewith the Directed Change Linking Rule. This account also explains why a directional phrase is neededor - at the very least - understood when agentiveverbs of manner of motion are usedcausatively. The presenceof such a phrase sanctionsthe alternative linking of the theme argument that permits the introduction of an external cause, explaining the contrasts below. (92a) (92b) (93a) (93b)

The general marched the soldiers to the tents. " The general marched the soldiers. The rider jumped the horse over the fence. * The rider jumped the horse.

Theexamplein (94)I shows that a phrasewith a directionalinterpretation.and not any type of locative phrase, is needed for the causative use. 29 We do not repeat this evidence here; see Hoekstra ( 1984), L. Levin ( 1986), Levin and " Rappaport Hovav ( 1992), C. Rosen ( 1984), among others.

verbsin English B. Levin, M. RappaportHovav/ Causative ( 94) 111ran the mouse around the box .

This example is unacceptable on the locative interpretation, which would involve the mouse running aimlessly around inside the box, but it improves on the directional interpretation where the mouse runs around the perimeter of the box. The constraint against locative phrasesreflects the fact that only directional phrasesallow for a directed change. The process which makes manner of motion verbs into verbs of directed motion is fully productive in English. Therefore, we would expect that the process which transitivizes these directed verbs of manner of motion to be fully productive as well, so that all class members should have a transitive causativeuse in the presenceof a directional phrase. 3o In fact, a wide variety of agentive verbs of manner of motion are attested in causative uses with directional phrases. 31 (95a) ... severalstrong Teamsters... shuffled Kit out of the room ... (L . Matera, A Radical Departure, 1988; Ballatine, New York , 1991, p . 79) " (95b) ... I promised Ms. Cain I would ride her around the ranch . . ." (N . Pickard, Bum Steer, Pocket Books, New York , 1990, p . 92) However, some of theseverbs do not seemto have such causatives. (96a) (96b)

* The trainer logged the runners to the finish line. * The leader climbed the team to the summit.

30 This account leavesunexplained the fact, noted also in Pinker ( 1989), that verbs of directed motion which are not verbs of manner of motion do not have causative counterparts: . She arrived the package ( at the store) . We believethat the lack of causativeswith theseverbs may not be a problem for our accou~t of causativesof verbs of motion . We suspectthat theseverbs are best not characterized as verbs of motion for several reasons, but rather they should be considered verbs of appearance. Interestingly, verbs of appearance, for reasons that we do not . fully understand, do not permit causative uses: The magician appeareda dove (from his sleeve) . Pinker suggeststhat the semantic conditions we formulate here are only necessaryconditions for participation in the alternations. He proposes that membership in lexically specified semantic subclasses of verbs determinesthe sufficient conditions for participation indiathesis alternations in general. These subclasses are implicated in what Pinker caDs narrow-range lexical rules. It remains to be seenwhether the lack of causative usesfor certain classesneeds to be stipulated lexically as Pinker suggestsor can be shown to follow from more general principles. 31 It is clear from the context that in (9Sb) the riders are actually on separatehorses; that is, the exampledoes not have the accompanimentinterpretation found in sentencessuch as I walkedmy dog, which might be argued to instantiate a distinct phenomenon from the phenomenon being discussedhere.

B. Levin. M. RappaportHovavI Causative verbsin English

The unavailability of certain causativescan be attributed to the Immediate Cause Linking Rule itself, which is fonnulated in tenDS of immediate causation . All of the sentenceswith transitive causativeusesof agentive manner of motion verbs imply somesort of coercion (a fact also noted in Pinker 1989). In fact, in the absenceof a particular context, these verbs sound best when the subject is human and the object is an animal, or else when the subject is someonein a position of authority and the object is under that authority . We attribute thesepreferencesto a need to construe such examplesin a way that the subjectcan be interpreted as the immediate causeof the eventuality. Some verbs of manner of motion describe types of motion that do not lend themselvesto an interpretation involving coercion, and such verbs are unacceptab in the causativeuse. This additional condition on causativizationis illustrated by verbs that describeaimlessmotion , such as stroll , mosey, meander and wander. Typically aimless motion cannot be brought about by coercion and, indeed, theseverbs appear not to have a causativeuse.

However, a search of text corpora did yield the following example of a causative use of stroll , suggestingthat in the right circumstanceseven these verbs can causativize, although a reviewer found this example unacceptable, as our analysis would suggest. (98) Julie Smith will stroll you through the Garden District , in New

OrleansM Durning...

(NewYorkTimes )

On this account, agentive verbs of manner of motion enter into a real ' ' processof causativization , in the sensethat the causativeform is the derived form. The account of the causativeforms of theseverbs contrasts with that of the causative forms of verbs like break, which we have argued are basically dyadic and enter into a process of detransitivization. This analysis, as we mentioned in section 3, is corroborated by the fact, noted in Hale and Keyser ( 1987), that cross-linguistically it is the causative form of such verbs which tends to be morphologically marked. 32 32 Another fact which suggests that the pr~ involvedwith verbsof mannerof motion is differentfrom theoneinvolvedwith verbsof changeofstatc is pointedout by Reinhart( 1991 ). She notesthat the introducedsubjectin a transitiveuseof a verb of mannerof motion must be an agent, not an instrumentor naturalfon:e. CompareTheriderjumpedthehorseoverthefencewith . Thewhip/thelightningjumpedthehorseoverthe fence. Thispropertyis alsonotedin Cruse( 1972 )

verbsin English B. Levin, M. RappaportBovav/ Causative

Our account of the transitive use of verbs of manner of motion is different from our account of the transitive use of verbs of emission. We have claimed that certain verbs of emission can be construed as being externally caused; becauseof that, a directional phraseis not required to effect a changefrom an unergativeto an unaccusativeverb. In contrast, verbs of manner of motion are never really consideredexternally caused, so that a directional phrase must be introduced to effect t.hechangein the classificationof the verb from unergative to unaccusative. The introduction of the new external causeis constrained in that the external causemust somehowbe construed as an immediate cause. In fact, as we discuss at greater length in Levin and Rappaport Hovav (to appear), even with certain inanimate emitters, the emission of the sound does not come about by direct manipulation of the emitter, so that causativesare only possible in the presenceof a directional phrase (e.g., The driver roared/ screechedthe car into the driveway). That is, the situation reducesto precisely the situation observedwith agentiveverbs of manner of motion. The crucial part that the directional phrase plays in sanctioning the causative use of agentive verbs of manner of motion is brought out by comparing the behavior of the verbs run and roll . The verb roll , although a manner of motion verb, is not necessarily agentive and falls rather into ' Jespersen' s ' move class. As discussedat the end of section 7, the type of motion that roll denotes can be either internally caused OT, when brought about by an agent or a force such as a push or gravity , externally caused. Depending on whether the verb roll is understood as internally or externally caused, monadic roll would be predicted to behave either as an unaccusative or as an unergative verb. When the verb takes an animate agentive argument, it would be expectedto show unergative behavior since the rolling would be internally caused. In fact, when the verb takes an animate subject, it can be found in the prepositional passive construction, a construction that Perlmutter and Postal ( 1984) argue is only possible with unergative verbs. (99) This carpet has been rolled on by three generationsof children. When its argument is inanimate, the eventuality denoted by the verb would be externally caused. The argument would be an internal argument by the Default Linking Rule, since neither of the other two linking rules would be applicable, and the verb would be expected to show unaccusativebahavior. In fact, the verb cannot be found in an unergative type resultative construction with an inanimate subject, as shown in ( I OOa), though it can be found in an unaccusativetype resultative construction, as shown in ( l00b ) .

B. Levin HovavI Causative verbsin English , M. Rappaport ( I OOa) * The bowling balls rolled the markings off the floor . (cr. The basketball players dribbled the markings off the floor .) I ( OOb) The door rolled open/ shut. This account of why roll can be unaccusativedoes not make referenceto a directional phrase, contrasting with the account of why run can be unaccusative . However, like unaccusative run, unaccusative roll should allow for a causativecounterpart, though again without the necessaryaccompanimentof a directional phrase. As predicted, the verb roll can be used causatively even in the absenceof a directional phrase. ( I Ola) The bowling ball rolled (into the room ) . ( I Olb) The bowler rolled the bowling ball (into the room) . The contrasting behavior of the verbs roll and run supports our account of thesetwo verbs.

9. Conclusion

In this paper we have unravelled someof the puzzlesconcerningthe causative alternation. Central to our analysis is the distinction betweenverbs which are inherently monadic and verbs which are inherently dyadic. This distinction is related to - but not reducible t033 - the distinction betweenunaccusativeand unergativeverbs. With respectto the phenomenathat havecome under the label 'causativealternation' we have , suggestedthat the more productive processin 'detransitive' verbs from lexical transitive causative is one which forms English verbs, as in the case of the verb break. Some verbs, such as buzz have both transitive and intransitive usessincethe meaningof the verb is compatible with both internal and externalcausation; this phenomenonis restrictedonly to those verbs which are indeedcompatible with both interpretations. Transitivization of agentiveverbs of manner of motion involves the introduction of an agent to an inherently monadic verb when, due to the presenceof a directional phrase, the verb no longer takesan externalargument. We hope that this study of causative verbsin English will help to illuminate our understandingof the much discussed , still elusive notion of . , though transitivity 33 We argue in Levin and Rappaport Hovav (to appear) that verbs of inherently directed motion such as arrive are unaccusativeand monadic.

B. Levin, M . Rappaport Hovav I Causativeverbsin English

References Anderson . Commentson the paper by Wasow. In: P. Culicover, A. Akmajian, , S.R., 1977 T. Wasow(eds.), 1977 , 361- 377. Baker, M., 1988 . Incorporation: A theory of grammaticalfunction changing . Chicago , IL : . Universityof ChicagoPress -inchoativealternation: A casestudyin parallelmorphology . TheCausative Borer, H., 1991 . The LinguisticReview8, 119- 158. Bresnan . Deep unaccusativityin LFG. In: K. Dziwirek, P. Farrell, . J. and A. Zaenen , 1990 E. Mejias-Bikandi (eds.), Grammaticalrelations: A cross-theoreticalperspective , 45- 57. Stanford, CA: CSLI, StanfordUniversity. Brousseau . A non-unifiedanalysisofagentiveverbs. WCCFL 10. , A.-M. and E. Ritter, 1991 -Bindingapproach Burzio. L., 1986 . Italian syntax: A Government . Dordrecht: Reidel. . On linking: Papersby RichardCarter. (LexiconProjectWorking Papers25, Carter, R., 1988 editedby B. Levinand C. Tenny.) Cambridge , MA : Centerfor CognitiveScience , MIT . . Languageuniversalsand linguistic typology. Chicago Comrie, B., 1981 , IL : University of .' ChicagoPress Cruse. D.A., 1972 . A noteon Englishcausatives . LinguisticInquiry 3, 522- 528. Culicover . Formal syntax. New York: Academic . P., A. Akmajianand T. Wasow(eds.), 1977 . Press Dixon, R.M.W., 1982 . Wherehaveall the adjectivesgone? In : R.M.W. Dixon, Wherehaveall the adjectives ? and syntax, 1- 62. Berlin: Mouton. gone and otheressaysin semantics . Word meaningand Montaguegrammar. Dordrecht: Reidel. Dowty, D.R., 1979 . Thematicproto-rolesand argumentselection . Language67, 547- 619. Dowty, D.R., 1991 Fillmore, C.J., 1967 . The grammarof hilling and breaking . In: R. Jacobs , P. Rosenbaum (eds.), Readingsin Englishtransformationalgrammar, 120- 133. Waltham, MA : Ginn. Fillmore, C.J.. 1968 . The casefor case. In: E. Bach, R.T. Harms(eds.), Universalsin linguistic 1 88 . New York: Holt, Rinehartand Winston. , theory Fontenelle . Retrievingergativeverbs from a lexical data base. , T. and J. Vanandroye , 1989 DictionariesII , 11- 39. . On Berberverbsof change: A study of transitivity alternations Guerssel . (Lexicon , M., 1986 , MA : Centerfor CognitiveScience , MIT . ProjectWorkingPapers9.) Cambridge Hale. K.L. and S.J. Keyser . Sometransitivity alternationsin English. (LexiconProject , 1986 7. , , MIT . ) WorkingPapers CambridgeMA : Centerfor CognitiveScience Hale, k .L. and S.J. Keyser, 1987 . A viewfrom the middle. (LexiconProjectWorkingPapers10.) , MA : Centerfor CognitiveScience , MIT . Cambridge . More on the typology of inchoative . In: , M., 1993 /causativeverb alternations Haspelmath B. Comrie(ed.), Causatives : Benjamins . and transitivity. Amsterdam Hoekstra . Transitivity. Dordrecht: Foris. , T., 1984 . Smallclauseresults. Lingua74, 101- 139. Hoekstra , T., 1988 Hoekstra . Aspectand thetatheory. In: I.M. Roca(ed.), 1992 . T., 1992 , 145- 174. . Oxford advancedlearner's dictionary of current English. Oxford: Hornby, A.S. (ed.), 1974 . Oxford UniversityPress . Semanticstructures Jackendoff . Cambridge . , R.S., 1990 , MA : MIT Press Jesperse n, 0 ., 1927 . A modemEnglishgrammaron historicalprinciples : , Volume3. Heidelberg Carl Winters.

B. Levin, M. Rappaport Hovav/ Causative verbsin English . On the middleandergativeconstructions in English. Linguistic , 1984 Keyser,S.J. andT. Roeper Inquiry 15, 381- 416. Lakoff, G., 1968 . Someverbsof changeand causation . (Report NSF-20.) Cambridge , MA : Aiken ComputationLaboratory, HarvardUniversity. Lakoff, G., 1970 . Irregularityin syntax. New York: Holt, Rinehartand Winston. Levin, B., 1989 . The Basqueverbalinventoryandconfigurationality . In: L. Maracz , P. Muysken : The typologyof asymmetries , 39- 62. Dordrecht: Foris. (eds.), Configurationality Levin, B., 1993 . Englishverbclasses . Chicago and alternations : A preliminaryinvestigation , IL : . Universityof ChicagoPress Levin, B. and M. RappaportHovav, 1992 . The lexical semanticsof verbs of motion: The from unaccusativity . In: I.M. Roca(ed.), 1992 , 247- 269. perspective Levin, B. and M. RappaportHovav, to appear. Unaccusativity : At the syntax-lexicalsemantics interface . Cambridge MA : MIT . Press , Levin, L., 1986 . Operationson lexicalfonDS: Unaccusative rulesin Germaniclanguages . PhiD. thesis , MIT . Marantz, A.P., 1984 . On the natureof grammaticalrelations.Cambridge . , MA : MIT Press Marantz, A.P., 1992 . The wayconstructions in English. In: and thesemantics of directarguments T. Stowell, E. Wehrli (eds.), Syntaxand semantics , Vol. 26: Syntaxand the lexicon, 179- 188. New York: AcademicPress . . Lexicalinsertionin a transfonnationalgrammarwithout deepstructure. , J.D., 1968 McCawley CLS 4, 71- 80. Reprintedwith notesin: J.D. McCawley , 1973 , Grammarand meaning , 154166. Tokyo: Taishukan . . Nekotoryeverojatnostnye universaliiv glagol'nom slovoobrazovanii . In: Nedjalkov, V.P., 1969 ' I.F. Vardul (ed.), Jazykovyeuniversaliii lingvisticheskajatipologija, 106- 114. Moscow: Nauka. . The typologyof morphologicaland lexicalcausatives . Nedjalkov, V.P. and GiG. Silnitsky, 1973 In: F. Kiefer (ed.), Trendsin Soviettheoreticallinguistics , 1- 32. Dordrecht: Reidel. Perlmutter . Impersonalpassives and the Unaccusative . BLS4, 157- 189. , D.M., 1978 Hypothesis Perlmutter . The I -AdvancementExclusiveness Law. In: D.M. , D.M. and P. Postal, 1984 Perlmutter , C. Rosen(eds.), 1984 , 81- 125. Perlmutter . Studiesin RelationalGrammar2. Chicago, IL : , D.M. and C. Rosen(eds.), 1984 . Universityof ChicagoPress Pinker, S., 1989 . Learnabilityand cognition: The acquisitionof argumentstructure.Cambridge , MA : MIT Press . . Longmandictionaryof contemporaryEnglish. London: Longman Procter, P., et al. (eds.), 1978 Group. . Semantics and the lexicon. Dordrecht: Kluwer. , J. (ed.), 1993 Pustejovsky . What to do with theta-roles. In: W. Wilkins(ed.), Syntaxand , M. and B. Levin, 1988 Rappaport semantics . , Vol. 21: Thematicrelations, 7- 36. New York: AcademicPress . Lexique7, . Niveauxde representation lexicale , , 1988 RappaportM., B. Levinand M. Laughren 13- 32. Appearsin Englishas: Levelsof lexicalrepresentation . In: J. Pustejovsky , (ed.), 1993 37- 54. . Lexicalpropertiesof ergativity. Paperpresented Reinhart, T., 1991 at the Workshopon lexical and lexicalinsertion, December9- 11, 1991 . Utrecht, The Netherlands : Research specification Institutefor Languageand Speech , Universityof Utrecht. Roca, I.M., 1992 . Thematicstructure: Its role in grammar. Berlin: Walterde Gruyter.

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. The interfacebetweensemanticroles and initial grammaticalrelations . In : Rosen , C., 1984 D.M. Perlmutter , C. Rosen(eds.), 1984 , 38- 77. . Argumentstructureand complexpredicates . BrandeisUniversity. (PhiD. Rosen , S.T., 1989 thesis .) . Lesverbesa la fois transitifset intransitifs en Fran~ s contemporain . , M., 1974 Rothemberg The Hague: Mouton. . Theoriesyntaxiqueet syntaxedu Fran~ is. Paris: Editionsdu Seuil. Ruwet, N., 1972 . The grammarof causativeconstructions : A conspectus . In: M. Shibatani Shibatani , M., 1976 , Vol. 6: Thegrammarof causativeconstructions , 1- 40. NewYork: (ed.), Syntaxandsemantics . AcademicPress . Resultatives . In: L. Levin, M. Rappaport , J., 1983 , A. Zaenen(eds.), PapersinLexicalSimpson FunctionalGrammar, 143 --157. Bloomington , IN : IndianaUniversityLinguisticsClub. ' classand causativeverbs in . Jesperse n's ' move and change Smith, C.S., 1970 English. In : M.A. Jazayery , E.C. Palome , W. Winter (eds.), Linguisticand literary studiesin honor of ArchibaldA. Hill , Vol. 2: Descriptivelinguistics , 101- 109. The Hague: Mouton. of motion . In : J.P. Kimball (ed.), Syntaxand semantics L. 1975 . Semantics and , syntax Talmy, , . Vol. 4: 181-238. New York: AcademicPress . Lexicalizationpatterns: Semanticstructurein lexicalforms. In: T. Shopen(ed.), Talmy, L., 1985 and the lexicon, , Vol. 3: Grammaticalcategories Languagetypologyand syntacticdescription . : CambridgeUniversityPress 57- 149. Cambridge . PhiD. thesis . Grammaticalizing , MIT . aspectand affectedness Tenny, C., 1987 . Transformations and the lexicon. In: P. Culicover, A. Akmajian, T. Wasow Wasow , T., 1977 , 327- 360. (eds.), 1977 . In: J. Pustejovsky(ed.), . Unaccusativityin Dutch: An integratedapproach Zaenen , A., 1993 1993 , 129- 161.

Section 2

thewordunits Discovering

) 81- 104. North-Holland Lingua92 ( 1994

Segmentation

problems , rhythmic

solutions *

Anne Cutler . . MedicalResearch Council.AppliedpsychologyUnit. 15 ChaucerRoad. Cambridge CB22EF. UK Thelexiconcontainsdiscreteentries,whichmustbe locatedin speechinput in orderfor speech to be understood ; but the continuity of speechsignalsmeansthat lexicalaccessfrom spoken . The speechenvironmentof prelinguistic input involvesa segmentation problemfor listeners infantsmaynot providespecialinformationto assistthe infant listenersin solvingthis problem. Maturelanguageusersin possession of a lexiconmight be thoughtto be able to avoid explicit segmentationof speechby relying on information from successfullexical access ; however , evidencefrom adult perceptualstudiesindicatesthat listenersdo use explicit segmentation -specific . Theseproceduresdiffer acrosslanguagesand seemto exploit language procedures . structure Efficient as these are not have been rhythmic procedures , they may developedin responseto statisticalpropertiesof the input, becausebilinguals, equally competentin two onerhythmicsegmentation . Theorigin of rhythmic , apparentlyonly possess procedure ;languages ' segmentation may thereforelie in the infant s exploitationof rhythm to solvethe segmentation . Recentevidencefrom speechproduction problemand gain a first toeholdon lexicalacquisition and perceptionstudieswith prelinguisticinfantssupportsthe claim that infantsare sensitiveto . rhythmicstructureand its relationshipto lexicalsegmentation

I . Introduction: Using the lexicon in listening to speech The lexicon, which is the focus of the present collection of papers, is assumed to be an essential component of every language user' s linguistic apparatus. The contents of a lexicon are so patently language-specific that it goeswithout saying that a lexicon cannot be inborn - it must be acquired, on the basis of linguistic experience. Such experienceusually consists of hearing utterances, which typically are many words in length. But we can safely . Financialsupportis acknowledged from the Human Frontier ScienceProgram. Thanksas with whom the many and variedexperimentssummarised herewere alwaysto the colleagues carriedout: Sally Butterfield, David Carter, Giyoo Hatano, PeterJusczyk , JamesMcQueen , JacquesMehler, Dennis Norris, TakasmOtake and Juan Segui. For discussionsand other with this paperthanksto MelissaBowerman assistance , Sally Butterfield, Mike Kelly, James . , JacquesMehler, DennisNorris and Ann Peters McQueen . . AnneCutler is now at Max PlanckInstitutefor Psycholinguistics , P.O. Box 310, 6500AH . , The Netherlands Nijmegen - 3841/94/507.00 @ 1994- ElsevierScienceB.V. All rightsreserved 0024 -A SSDIOO24-3841( 93) EOO39

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assumethat complete utterancesare not what lexicons consist of. The number of utterances is potentially infinite , so that to store all the utterances we might ever hear our lexicon would also have to have infinite capacity. Even if we set an arbitrary length limit , the number of possible utterances is enormously large; for instance, Miller ( 1967) calculated that there must be at least 1020possible English sentencesof twenty words or less - a total which, he drily added, would take considerably longer than the estimated age of the earth to speak. Instead, we assume that the contents of a lexicon consist of sound-tomeaning mappings in discrete chunks. ( Wecan refer to lexical entries by the shorthand term ' words' , although of course not aU lexical entries necessarily correspond to what would be written as a single separate word. Some subword forms such as affixes or stem morphemes may well have lexical representation, as may particles which are conjoined with other words in writing ; likewise, multi -word idiomatic expressionsand frequently occurring phrasesmay be representedby a single entry .) Thus using a lexicon requires the separation of utterances into the lexically relevant chunks of which they are made up - producing speechrequires the languageuser to string together lexical entries to make a whole utterance, and recognising speech requires division of an utterance into units which can be looked up in the lexicon. Likewise, acquiring a lexicon eventually involves acquiring the ability to use it in theseways. The present contribution focusseson the very start of lexicon-building : how the infant might find out what words in the input languageare like , and might assemblean initial stock of known words. The initial task is perceptual. What exactly does it involve? For instance, does it involve (as mature useof a lexicon in speechrecognition involves) division of multiword utterancesinto lexically relevant chunks? And if so, how difficult is this task? To answer thesequestions we need to consider the nature of the speechinput with which the infant is most likely to be confronted. Comparative studies of various types of speechare consideredin the next section.

2. Stylesof adult - directetl

speech

Most of the speechany listener hears is spoken spontaneously- the speech signalswhich occur in the majority of everydaysituations have beenconceived and composed by their speakerseven as they are uttered. For most listeners, spontaneous speech is encountered far more often than other styles such

A. Cutler / Segmentationproblems

as rehearsed speech (heard in the theatre or on radio or television, for example), read speech (in news broadcasts, or , too often, in lectures) or computer-synthesisedspeech. Whatever the style of speech, words in isolation occur only rarely - nearly all utterances are multiword . A lot is known about the phonetics of multiword utterances, and a fair summary of our knowledge is that words are strongly affected by the contexts in which they occur; moreover, these contextual assimilation processes operate to obscure word boundaries, with the result that there are few reliable cues in a continuous speechsignal to where one word ends and the next begins. Klatt ( 1989) provides a telling overview of the problems which this causesfor the lexical accessprocess so essentialfor speechrecognition. Nevertheless, the majority of such phonetic studieshave beenconducted on speechproduced in laboratory situations, which is normally read speech. Is this a fair representation of the speech which most listeners usually hear? Motivated by this question, speechscientists have undertaken a number of studies aimed at describing spontaneous speech, and becauseof the underlying motivation , most of the studies have been comparative: spontaneous speech has been contrasted with read speech. These studies have revealed systematic differences between the two types of speech. Some of these differences might render the listener' s problems even worse in spontaneous than in read speech. For example, casual spontaneousspeechis particularly prone to phonological elisions and assimilations (G. Brown 1977, Labov 1972, Milroy 1980) and to syntactic simplifications and, occasionally, incompleteness (Cheshire 1982, Labov 1972) . Other differences, however, might make life easier for listeners to spontaneous speech. These are principally differences in the prosodic domain. Thus spontaneous speech tends to be produced at a slower rate than read speech(Barik 1977, Johns-Lewis 1986, Levin et al. 1982), and to have longer and more frequent pauses and hesitations (Barik 1977, Crystal and Davy 1969, Kowal et al. 1975, Levin et al. 1982) and shorter prosodic units (Crystal and Davy 1969) . Listeners can distinguish spontaneous utterances either from read speech (Levin et al. 1982, Remezet al. 1985, Blaauw 1991) or from rehearsedspeech (Johns- Lewis 1987) ; their judgements are most likely based on prosodic aspectsof the speech, becauseaccuracy is still high when the speechextracts have been low-pass filtered (Levin et al. 1982), while the distinction can not be as accurately made on written versions of the text (Johns- Lewis 1987) . Fluent spontaneous speech can be identified as accurately as disftuent (Blaauw 1991).

A. CullerI Segmentation problems

The prosodic differencesbetweenspontaneousand read speechhave consequences for the way speechin each mode is processedby listeners. McAllister ( 1991) examined word recognition in spontaneousand read speechusing the gating task, in which listeners hear successivelylarger fragments of a word. She found that word identification (in context) occurred earlier for a word stressedon the first rather than on the secondsyllable in spontaneousspeech, but not in read speech. In a word -by-word gating study of spontaneous speech Bard et ale ( 1988) and Shillcock et ale ( 1988) similarly found that words containing strong syllables were easier to identify than words which were realised as weak syllables. Mehta and Cutler ( 1988) investigated phoneme detection reaction time in spontaneous and read speech, and compared in particular the relative strength in the two speech modes of a number of previously established effects. They found no overall difference in responsetime between the two speech modes, and also no difference between the two modes on the one semanticvariable in the study, the effectsof the transitional probability of the target-bearing word. However, four other effects differed across modes. In read speechbut not in spontaneous speech, late targets were detected more rapidly than early targets, and targets precededby long words were detected more rapidly than targets preceded by short words. In contrast, in spontaneous speechbut not in read speech, targets were detected more rapidly in accentedthan in unaccentedwords and in strong than in weak syllables. Mehta and Cutler explained these differencesin terms of prosodic differences betweenthe two speechmodes. The greater frequency of hesitations in spontaneousspeech, for example, results in shorter prosodic units, which in turn reduces the average span over which rhythmic predictability will hold. So becauseprosodic units are long - generally clause-length - in read speech, but usually short in spontaneous speech, the opportunity for rhythmic prediction in the latter case is much smaller. Mehta and Cutler thus argued that position in the sentence is not , strictly speaking, what affects target detection time ; rather, the effective variable is position in the prosodic unit . Similarly, becausehesitations tend to be more frequent and longer in spontaneous speech,,it is much more likely that a particular target-bearing word will be precededby a hesitation in the spontaneousthan in the read mode. Where a target is immediately preceded by a hesitation, any effects of incomplete processingof the previous word will be nullified by the extra processingtime provided by the hesitation, so that effectsof precedingword length, which are held to reflect just such processinghangovers from the preceding word , will be lesslikely . Finally , becauseaccent patterns in spontaneousutteranceswere

A. Cutler / Segmentationproblems

more varied and less likely to expressdefault accenting than those in read utterances, and the acoustic differences between strong and weak syllables were greater in spontaneousthan in read speech, there was greater opportunity for processing effects of both sentence accent and syllable stress to appear in the spontaneousthan in the read speech; this would account for the finding of significant facilitation due to sentenceaccent and syllable stressin the fonner but not in the latter. The results of the gating studies described above provide similar evidenceof the perceptual importance of syllable stress in spontaneousspeech. These findings speak to the majority case for speech processing. Most speech that adult listeners hear is spontaneously produced. Such speech is characterised by a fairly slow overall rate of speech, short prosodic units, frequent pausesand, in English, a clear opposition betweenstrong and weak syllables. These factors affect the way the speechis processed.

3. The infant's speechenvironment Is the infant ' s speechenvironment the sameas that of an adult listener? In one respect it is not , becausespeechdirected to the infant as chosen listener exhibits a pattern which is systematicenough to warrant calling it a separate speechstyle. This conclusion emergesfrom a number of studies which have investigated the characteristics of speech addressed to young children at various stagesof development; again, the studies have mainly been comparative , with infant -directed spontaneousspeechbeing typically contrasted with speechfrom the same speakersto adults. In European languages, infant -directed speech tends to be spoken at a slower rate, to have more frequent stresses, shorter continuous sequencesand longer pauses, and to be higher in pitch than adult-directed speech(Fernald and Kuhl 1987, Fernald and Simon 1984, Fernald et al. 1989, Garnica 1977, Stern et al. 1983) . Slower rate, more frequent prosodic demarcation, and longer pauses, it will immediately be noted, are the primary factors which the review in the previous section revealed as distinguishing spontaneous from ' non-spontaneousspeech. To the present author s knowledge thesetwo literatures have not been directly compared; there would seemto be a defensible case, however, for considering adult-directed and it:tfant-directed spontaneous speechin terms of a single continuum , with infant ~directed speechoccupying a more extreme position on most measures.

A. CutlerI Segmentation problems

The one exception is that infant -directed speechis reported to have higher pitch and a wider fundamental frequency range ( Fernald and Simon 1984, Garnica 1977) . In contrast, the fundamental frequency range of spontaneous speechhas been reported in at least some studies to be relatively narrow , at least in intimate conversation (Johns-Lewis 1986, Blaauw 1991) . Pitch is a particularly important dimension of infant -directed speech, since the fact that infants prefer to listen to this style of speech(Fernald 1985) has been found to be principally due to its pitch characteristics (Fernald and Kuhl 1987, Sullivan and Horowitz 1983) . Ohala ( 1983, 1984) has argued that raised pitch is an ethologically universal signal of smallness, ingratiation and non-threatening attitude. From such a perspective it would be possible to argue that raised pitch might not be a phonologically relevant manipulation in speechto infants, but might simply arise from universal expressionof affection or nurturance on the part of an adult to an infant . Against this conclusion, on the other hand, might be cited the more recent findings that the pitch manipulations found in infant -directed speech in American English and related languagesare apparently not universal . Although rising contours predominate in infant -directed speechin the stresslanguagesEnglish (Sullivan and Horowitz 1983) and German (Fernald and Simon 1984), falling contours are more prevalent in the tone languages Mandarin (Grieser and Kuhl 1988) and Thai (Tuaycharoen 1978) . In a comprehensive review of the literature on pitch in infant -directed speech, Shute ( 1987) concluded that pitch modifications are not only clearly not universal across languages, but may also differ within one language as a function of sex of the speaker, age of the child addressee , frequency of the ' s interaction with children and other factors. speaker In fact a recognisablestyle of infant -directed speechis itself not universal, contrary to the confident expectations of researchersin the 70s that it would prove not only to be universal (Ferguson 1977) but absolutely necessaryfor successfulacquisition (R. Brown 1977) . It is now clear that there are cultures where infants are exposedto much normal adult speechbut no speechin any special infant -directed mode (Heath 1983, Schieffelin 1985, Schieffelin and Ochs 1983) . Even where infant -directed speech appears to conform to the pattern obserVedin English and like languages, this may not constitute a specialisedmode; thus infant -directed speechin Quiche Mayan has relatively high pitch , but so, in this language, does adult -directed speechfrom the same informants (Bernstein-Ratner and Pye 1984) . Thus it is reasonable to conclude that infants in the earliest stages of - and for some language acquisition receive at least some of their input

A. Cutler/ Segmentation problems

infants, perhaps all of their input - in a fonn that at least closely resembles nonnal spontaneous speech between adults. One of the characteristics of spontaneousspeech, it will be recalled, is the high frequency of phonological elisions and assimilations (G. Brown 1977, Labov 1972, Milroy 1980) . Some studies have reported that child -directed speech, too , is replete with such distorting processes (Bard and Anderson 1983, 1991; Shockey and Bond 1980), which is consistent with the view that this style of speechlies on a generalcontinuum with adult-directed casual speech. Other studies, however, have reported lower frequency of distorting phonological transformations in speechto infants than in speechto adults (Bernstein- Ratner 1984a,b) . In an attempt to resolve this apparent contradiction , Stoel-Gammon ( 1984) transcribed five hours of speechto one-year-olds; her results strongly support the view of a continuum , since she effectively discovereda continuum within her own data, from very clear articulation (e.g. releaseof word -final stop bursts, clear articulation of unstressedvowels) to very casual forms (frequent vowel reduction, omissions of whole syllables such as [sko] as a pronunciation of ' let s go) . Stoel-Gammon concluded that the phonological characteristics of speech to children depend on such factors as contextual redundancy, the function of the individual utterance, and the situational context - the same factors that determine the phonologicalforms of adult spontaneous speech (Liebennan 1963, Cheshire 1982) . There is to my knowledge no evidence, from any culture, of a greater incidence of isolated words in speech to children than in other forms of speech. Even though phrases may be short, they are still phrases. Thus a speechsegmentationproblem, as describedin the introductory section to this paper, seemsto exist for the infant as for the adult languageuser. The speech ' that the infant hears is continuous; much of the speech of the infant s environment will be speech among mature language users; in perhaps a majority of cultures speechaddressedspecifically to the infant would fonn only a small proportion of the input ; even then, such speech may not necessarilybe clearly articulated. The problem is compounded for the infant by the necessity of compiling a lexicon, and this added difficulty does not trade off against reduced segmentation difficulty in the input . In fact, the scaleof the segmentationproblem in the structure of the input is remarkably similar for the infant and for the adult.

A. CutlerI Segmentation problems 4. The segmentation problem for adult listeners

The adult listener typically hears continuous multiword utterances, and must therefore segmentthe speechstream in order to understand them. The importance of this segmentation problem has long been acknowledged, and many, widely varying, experimental approaches have tackled the question (e.g. Hayes and Clark 1970, Wakefield et al. 1974, Pilon 1981) . But the adult ' s situation differs from that of the child becauseas a mature language user the adult is already in possession of a lexicon. This has led some researchersto claim that the adult listener has no need of explicit segmentation procedures, since the successfulrecognition of a word will ensure that whatever immediately follows that word will be known to be word -initial . For example, Cole and Jakimik ( 1978) proposed that recognition of spoken utterances proceeds in strictly temporal order, and ' one word ' s recognition ' automatically 'directs segmentationof the immediately following word ' ( 1978: 93) . We could call such a model ' segmentationby default' . On closer inspection, though, it becomes obvious that segmentation by default could not work , at least for English. Firstly , the model relies on listeners being indeed able to determine where a word ends. It is true that sometimesphonetic sequenceconstraints will be of use in this. Somesequences of phonemes- [au k ], [m g] , [ai S] , for example - never occur word -internally in English (Lamel and Zue 1984, Harrington et al. 1987) ; thus a sentencelike How comeGuy shaved? should prove very easyto segment. But unfortunately such helpful sequencesare rare. As McQueen and Cutler ( 1992) have recently demonstrated, the English vocabulary contains few totally distinct words ; most long words have other words embedded in them (as reconciliation contains wreck, reckon, sill , silly , ill , etc.), while most short words occur within longer words (as late can be found in latency, collate, belated, ' translatability, etc.) . Moreover, McQueen and Cutler s computations showed that the majority of such overlaps occur at the beginnings of the longer words, a particular problem for segmentationby default. Of course, in typical English speechthe majority of words are monosyllabic Cutler and Carter 1987), which will certainly reduce the problems causedby ( such embeddings. But most monosyllabic English words do not become unique until at or after their final phoneme (Luce 1986) ; and in fact many words - especially monosyllabic words - can not be recognised until after their acoustic offset. Post-offset recognition has been demonstrated both with laboratory -produced (i.e. carefully read) speech (Grosjean 1985), and with spontaneously produced speech(Bard et al. 1988, Shillcock et al. 1988) . If

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words cannot be recognisedtill after their ends then segmentationby default would lose its very basis. Secondly, models such as segmentationby default are far from robust ; they assumethat prelexical processingof the speechsignal will be accurate. But in practice speechsignals are not always fully clear. Background noise, distance between speaker and listener, distortion of the speaker's vocal tract , foreign accents, slips of the tongue - all these, and similar factors, conspire to make the listener' s phonetic interpretation task harder. A much more robust model is neededto account for what is obviously true, namely that human speech recognition is extremely successful even under noisy conditions or with previously unfamiliar voices or accents.

S. A solutionfor English: Rhythmicsegmentation In fact there is a good deal of evidencefrom human speechrecognition in English that explicit segmentationprocedures.are employed by adult listeners. Cutler and Norris ( 1988) suggestedthat the characteristic rhythmic structure of English could form the basis for an effective segmentation procedure, becauseEnglish speech shows a systematic relationship between rhythmic patterns and word boundary locations. The rhythm of English is based on stress, with syllables of the language being either strong or weak; strong syllables contain full vowels, while weak syllables contain reduced vowels (usually schwa) . Cutler and Carter ( 1987) demonstrated that English lexical words are far more likely than not to begin with strong syllables - in a -word phonetically transcribed dictionary (the MRC Psycholinguistic 33,OOO Database: Coltheart 1981, Wilson 1988), 73% of all entries had strong initial syllables. But the frequency of occurrenceof individual words differs widely; lexical, or content words, are sometimesvery common (e.g. people), but more often are very rare (e.g. peon, steeple), while some words which inrunning speech are usually realised as weak syllables - grammatical, or function words, such as of or the - occur very frequently. Cutler and Carter examined -word natural speech sample, the Corpus of English Conversation a 190,OOO Svartvik and Quirk 1980), using the frequency count of this corpus prepared ( by Brown ( 1984) ; they found that in this corpus 90% of the lexical words have strong initial syllables. However, the grammatical words in the corpus were actually in the majority , and they were virtually all weak monosyllables. Cutler and Carter computed that about three-quarters of all strong syllables in the sample were the sole or initial syllables of lexical words, while more

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than two-thirds of all weak syllables w~re the sole or initial syllables of grammatical words. This means that a listener encountering a strong syllable in spontaneous English conversation would seem to have about a three to one chance of finding that strong syllable to be the onset of a new lexical word. A weak syllable, on the other hand, would be most likely to be a grammatical word. English speech should therefore lend itself to a segmentation procedure whereby strong syllablesare assumedto be the onsetsof lexical words. Cutler and Norris interpreted results of an experiment they ran as evidencefor such a procedure. They used a task which they called word -spotting, in which listeners were asked to detect real words embeddedin nonsensebisyllables; detection times were slower to the embeddedword in , say, mintayf (in which the second vowel is strong) than in mintef (in which the second vowel is schwa) . Cutler and Norris interpreted this as evidence that listeners were segmenting mintayf prior to the second syllable, so that detection of mint therefore required combining speechmaterial from parts of the signal which had been segmentedfrom one another. No such difficulty would arise for the detection of mint in mintef, since the weak second syllable would not be divided from the preceding material. Further evidence for such a procedure was produced by Cutler and Butterfield ( 1992), who investigated the way in which word boundaries tend to be misperceived. In both spontaneousand experimentally elicited misperceptions they found that erroneous insertions of a word boundary before a strong syllable (e.g. achievebeing heard as a cheap) and deletions of a word boundary before a weak syllable (e.g. bird in being heard as burgling) were far more common than erroneous insertions of a boundary before a weak syllable (e.g. effective being heard as effect oJ> or deletions of a boundary before a strong syllable (e.g. were waiting being heard as awaken) . This is exactly what would be expected if listeners deal with the segmentation problem by assuming that strong syllables are likely to be word initial , but weak syllables are not. As Cutler and Norris point out , the strong syllable is defined by the quality of its vowel (full , in comparison to the reduced vowels of weak syllables) ; thus spotting strong syllables cannot provide a complete solution to the segmentation problem since word boundaries actually occur prior to the onset of syllables. A strong syllable spotter must be supplementedby some means of estimating actual syllable onset; Cutler and Norris suggest that more than one alternative realisation of such a device would be feasible. Assuming that a rhythmically based segmentation procedure is indeed prac

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tical , its advantages are considerable. For instance, such a procedure is obviously not going to be affected by the frequency of words embedded within other words in speech, or by the relative frequency of monosyllables versus polysyllables. Only where polysyllabic words contain strong syllables in non-initial position will the procedure produce a non-optimal result (i.e. it will signal a word boundary but this will be a false alarm) . However, polysyllabic words with non-initial strong syllables occur relatively rarely (Cutler and Carter 1987), and in only a small minority of them will a false alarm actually produce a real word unrelated to the embedding word (e.g. late in collate; Cutler and McQueen, in press). Thus rhythmic segmentationis a relatively efficient procedure for English. It is also quite robust - in fact, it is precisely with uncertain input that rhythmic segmentation proves particularly useful. R.esearchersin automatic speechrecognition (e.g. Shipman and Zue 1982) have developed systematic representationsof phonetic uncertainty, namely transcriptions in which only general classesof phoneme are provided (e.g. glide, nasal, stop consonant, etc.). Two studies using uncertain input of this kind have produced further evidence in favour of rhythmic segmentation. In the first study, Briscoe ( 1989) implemented four segmentation algorithms and tested their performance -word on a (phonetically transcribed) continuous input , using a 33,OOO lexicon. The algorithms postulated potential lexical boundaries: (a) at the ' ' end of each success fully identified word ( segmentation by default ); (b) at each phoneme boundary; (c) at each syllable onset; and (d) at each strong syllable onset (the rhythmic segmentation proposal) . The measureof performance was the number of potential lexical hypothesesgenerated (the fewer the better) . With completely specifiedphonetic input all algorithms naturally performed quite well. However, significant differencesbetweenthe algorithms emerged when some or all of the input was phonetically uncertain; most affected were ' segmentationby default' and the phonemic algorithm , both of which generated huge numbers of potential parses of incomplete input . Far better results were produced by the algorithms which constrained possible word onset positions in some way, and the more specific the constraints, the better the performance: the rhythmic segmentationalgorithm performed best of all with the uncertain input . In the second study, Harrington et al. ( 1989) compared the rhythmic segmentation algorithm with a segmentation algorithm based on permissible phoneme sequences(Lamel and Zue 1984, Har rington et al. 1987), using as a metric the proportion of word boundaries correctly identified in a 145-utterance corpus. With phonetically uncertain , but the rhythmic segmeninput, sequenceconstraints proved virtually useless

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tation algorithm still performed effectively (in fact it correctly detected more word boundaries in uncertain input tharl the phoneme sequenceconstraints had detectedin completely specifiedinput) . The efficiency and robustness of rhythmic segmentation therefore suggest that listeners profit from employing an explicit segmentation procedure of this kind . A striking fact about this procedure, however, is its languagespecificity: as described for English, the procedure is based on stressrhythm , i.e. the opposition of strong and weak syllables. Clearly, it therefore cannot be a universal strategy, becausemany (indeed most) languagesof the world do not have stress rhythm . However, all languages have rhythm - speech rhythm need not be stress-based. In the next section alternative forms of rhythmic segmentation are described, supported by the results from experiments in languageswhich do not have stressrhythm .

6. Rhythmicsegmentation in French and Japanese Mehler (e.g. 1981) and his colleagues(e.g. Segui 1984) have used a variety of psycholinguistic tasks to demonstrate processing advantagesfor syllables in speech comprehension. In one experiment, which launched a series of cross-linguistic comparisons, Mehler et al. ( 1981) had French subjects listen to lists of unrelated words and press a responsekey as fast as possible when they heard a specifiedword -initial sequenceof sounds. This target was either a consonant-vowel (CV) sequencesuch as ba- or a consonant-vowel-consonant (CYC) sequencesuch as hal- . The words which began with the specified sound sequencehad one of two syllabic structures: the initial syllable was either open (CY ), as in balance, or closed (CYC ), as in balcon. Mehler et al. found that responsetime was significantly faster when the target sequence corresponded exactly to the initial syllable of the target-bearing word than when the target sequenceconstituted more or less than the initial syllable. Thus responsesto ba- were faster in balancethan in balcon, whereasresponses to bal- were faster in balcon than in balance. Mehler et al. claimed that this result supported a syllabically basedsegmentationstrategy in speechrecognition in French. Similarly, Segui et al. ( 1981) found that listeners are faster to detect syllable targets than to detect targets corresponding to the individual phonemeswhich make up those samesyllables. Further evidencefrom French that polysyllabic words, whether they are heard in isolation or in connected speech, are analysed syllable by syllable came from studies by Segui ( 1984) and by Dupoux and Mehler ( 1990) .

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If speechsegmentation in French proceedssyllable by syllable, there is an interesting parallel to the results from English reported in the previous section. Just as use of the opposition between strong and weak syllables in ' segmentingEnglish exploits the English languages characteristic stress-based rhythmic pattern, so does use of the syllable in segmenting French exploit rhythmic patterns, since the characteristic rhythm of French is syllable-based. Recent results from studies of speech segmentation in a third language, , confinn the connection between segmentation and speechrhythm . Japanese In Japanese , speech rhythm is based on a subsyllabic unit called the mora which can a vowel, an onset-vowel sequence be ( , or a syllabic coda). Otake et al. ( 1993) conducted an experiment in Japanesewhich was directly analogous to the French experiment by Mehler et al. ( 1981) ; they compared detection of CV (e.g. la-) and CVC (e.g. tan-) targets in Japanesewords beginning with open ( tanishl) versusclosed ( tanshl) syllables. In both words the first mora is ' the initial CV sequence ta ; and detection of CV targets was equally fast in both words (had the Japanesesubjects been using a syllabic segmentation procedure, the CV targets should have been harder to detect in closed than in open syllables) . CVC targets constitute two morae, and correspond to the first two morae of the words with initial closed syllables; however, they do not correspond properly to a mora-based segmentation of words like tanishi (CV-CV -CV) . Indeed, the Japaneselisteners respondedto the CVC targets in words like. tanshi, but usually failed to respond in words like tanishi. Thus rhythmic segmentation seemsto be quite a widespread phenomenon across languages, with the nature of the rhythmic processing being determined ' by the nature of each languages characteristic rhythmic structure: stress-based, syllabic, or moraic rhythm can all be used in speechsegmentation by adult listeners. However, there turn out to be strict limitations on the way any listener can exploit speech rhythm in segmentation; and these limitations may illuminate the questions with which we started this chapter, namely those pertaining to how the prelinguistic infant first solves the segmentationproblem.

7. Limits to rhythmicsegmentation First of all , the cross- linguistic differences in speech segmentation are characteristics of the listeners and do not simply follow from the nature of the speech input . English monolinguals do not use syllabic segmentation in performing the target detection task with either English or French ( Cutler et

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al. 1986) ; neither English nor French listeners use moraic segmentationwhen performing the same task with Japanese(Otake et al. 1993). In other words, syllabic segmentationseemsto be specific to French listeners, moraic segmentation to Japanese listeners. (In fact the French listeners segmented both English and Japanesespeechby syllables, just as they segmentFrench!) Moreover, under appropriate conditions listeners can be seen to abandon the rhythmic segmentation procedures characteristic of their language community . When responding very fast, French listeners can base their responseson subsyllabic units (Dupoux 1993) . CVV sequencesare apparently less conducive to application of moraic segmentation by Japaneselisteners than the (more common) CVCV and CVN sequences(Otake 1992). The failure to find processing disadvantages for English words beginning with weak syllables when the words are carefully read, reported in the second section of this paper, may reflect a similar case: if the input is very clear, stress-basedsegmentationmay not need to be called into play. Thus it is quite clear that none of the rhythmic segmentation procedures constitutes an ' absolutely necessarycomponent of adult listeners speechprocessing. The strongestevidencethat this is so comes, however, from studiesof bilingual . Cutler et al. ( 1992) testedFrench-English bilinguals with the techniques processing which had demonstratedsyllabic respondingin French listeners(Mehler et al. 1981) and stress-based responding in English listeners(Cutler and Norris 1988). Their subjectswereas bilingual as they could find - eachhad learnedboth languagesfrom the earlieststagesof acquisition, spokeboth languagesdaily, and was acceptedas a native speakerby monolingualsin eachlanguage. Yet these bilinguals did not necesarilyproduce the pattern of results which monolinguals had shown on each previous experiment. Instead, their response patterns could be predicted from a measureof what Cutler et al. called ' ' language dominance , which amounted in essenceto a decision as to which of their two languagesthe bilinguals would be most sorry to lose. On Mehler et alis target detection task with French materials, only those bilinguals who ' chose French as their ' dominant language showed a syllabic pattern of responding; the English-dominant bilinguals showed no trace of syllabic ' effects. On Cutler and Norris word -spotting task, in contrast, a stress-based responsepattern appeared only with those bilinguals who chose English; the responsesof the French-dominant bilinguals were unaffected by the rhythmic pattern of the embedding nonsense word. Apparently , these maximally competent bilinguals had available to them in these tasks only one rhythmic segmentationprocedure - either that which was characteristic of one of their native languages, or that which was characteristic of the other, but not both.

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Of course, it should be rememberedthat this conclusion is based only on the results of laboratory experiments, and may not reflect the full extent of the resourceswhich bilinguals can apply to the processing of , for example, spontaneous speech; as earlier sections of this chapter described, different ' speechstyles may call differentially upon a listener s processing repertoire. However, the experiments undeniably show that in the laboratory some bilinguals can exploit a given rhythmic segmentation procedure, and do exploit it , while others certainly do not exploit the same procedure, and possibly cannot do so. A claim that , for example, French-dominant FrenchEnglish bilinguals are capable of stress-based segmentation, but abandon it when processing laboratory speech, ought therefore to be accompanied by an account of why Eoglish-dominant bilinguals, and monolingual English speakers, do not abandon this procedure in the laboratory . On the basis of the laboratory results alone, it would surely appear that bilinguals simply do not have available to them the segmentationprocedure characteristic of their non-dominant language. This is a remarkable finding in the light of the undoubted competenceof these bilingual speakersin both their languages. The English-dominant bilinguals spoke and understood French just as well as the French-dominant bilinguals did , and the latter group spoke and understood English just as well as the former. For those bilinguals who used stress-based segmentationwith English, the apparent unavailability of syllabic segmentation for use with French seemed to have no adverse effect on their linguistic competence; likewise, for those bilinguals who used syllabic segmentationwith French, the unavailability of stress-based segmentation seemednot to reduce in any way their demonstrated competencein English. These results may therefore indicate that the rhythmic segmentation procedures are not a necessarycomponent of a languageuser' s processingmechanism; one can demonstrate native competencewithout them. This in turn would imply that rhythmic segmentation procedures are not simply developed in responseto experiencewith the statistical properties of the native language, as the arguments made by, for instance, Cutler and Carter ( 1987) with respectto stress-basedsegmentationin English contended. There is no doubt that stress-based segmentation does work efficiently with English; but despite having been exposedto English since their earliest years, and despite using English with native competenceall their lives, the Frenchdominant bilinguals neverthelessdo not , in the word -spotting experiment, show evidenceof segmenting by stress. The question must be posed, therefore , of how the rhythmic segmentation procedures could arise, if it is

96

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arguably the casethat they may not result automatically from experiencewith the statistical properties of the native language. A possible answer to this question, proposed by Cutler et al. ( 1992) and by Cutler and Mehler ( 1993), is discussedin the next section.

Supposethat the rhythmic segmentati.on proceduresused by adult listeners exist not for purposes of adult processingat all , but are simply traces which remain from a peri.od when the segmentationproblem dominated the infant ' s language processing. Perhaps it is precisely the characteristic rhythm of the input languagewhich offers the infant a first toehold into lexical acquisition, by suggestinga possible segmentation of the continuous speechstream into discrete units. In the caseof the syllable in French, in fact, just such a model has been put forward by Mehler et al. ( 1990) . More generally, Cutler and Mehler ( 1993) have suggestedthat the infant enters the world already armed with what they have called aperiodicity bias' . The task of lexical acquisition is primed in that the infant expects that meaning will map to form ; the task is made possible by the fact that this expectation is targeted towards a particular kind of form : input which is periodically structured. Speechsignals have periodic structure, and for the majority of children speechwill be among the most salient forms of input available. In the first few months and even days of life infants prefer to listen to speech rather than to other auditory input (Colombo and Bundy 1981, Glenn et al. 1981). The contrast between the periodic structure of speech as opposed to random noise is only one level of structure, however; regular periodic structure in speechexists at several levels. At the level of the speechsound, some sounds are relatively ' more periodic' than others - for instance, vowels are relatively steady-state sounds, while consonants are often more transient. As Cutler and Mehler ( 1993) point out , this could account for the findings that infants acquire language-specific vowel prototypes at about six months of age (Kuhl et al. 1992), well before they acquire the consonantal phonology of their language ( Werker and Polka 1993) . At a higher level again is the rhythmic structure of language discussedin the preceding sections. It is not unreasonableto propose that at some point during the infant ' s prelinguistic period this level of rhythmic structure is also attended to , and that the processing that goes on at that point is intimately connected with lexical

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segmentation- dividing the continuous speechinto lexical units. Nor need the rhythmic structure be exclusively expressedin the auditory domain ; as Pettito and Marentette ( 1991) demonstrate, gestural language acquisition by congenitally deaf infants follows a developmentalpath with noticeable similarities to spoken languageacquisition. Because , as we have described, rhythmic structure differs even across spoken languages, the infant exposed to stress rhythm will focus upon a different regularity than the infant exposed to , say, syllabic or moraic rhythm . As Cutler et al. ( 1992) argue, this can be conceived of as the infant attending to the smallest level of regularity occurring in the spoken input . What is remarkable about this processis that it seemsto happen only once, if the evidence from the bilingual studies is reliable. That is, exposure to two differing rhythmic regularities (syllabic and stressrhythm , for instance) does not result in the ability to use both types of rhythm in speechsegmentation; a language user appears to be able to command only one rhythmic segmentation procedure. This type of all-or -none instantiation of a languageprocessing procedure is distinctly reminiscent of the notion of parameter-setting in syntactic processing(e.g. Wexier and Manzini 1987) .

9. Prosodyandthe preHnguisticinfant The notion of rhythmic segmentation by infants as a ' bootstrap' into the beginningsof lexical acquisition has not been directly tested. In this concluding section, however, researchon prosodic processingby prelinguistic infants will be reviewed in an attempt to discover whether there is evidence which could support the notions proposed above. First , though , it should be acknowledged that involvement of speechprosody in this level of language acquisition has been proposed by others in several forms. The suggestionby Gleitman and Wanner ( 1982; seealso Gleitman et al. 1987) that words are initially identified as units via their stressedsyllables is closely related to the application of the present proposal to languages with stress rhythm , for instance. Likewise, Jusczyk (e.g. 1993) has suggestedthat prosodic structure is the dimension which infant listeners exploit to accomplish speechsegmentation . In a series of experiments Jusczyk and his colleagues have shown that infants are sensitive to prosodic marking of syntactic structure, with sensitivity to clausal prosody emerging by four to five months of age (Hirsch -Pasek et al. 1987) , and sensitivity to phrasal prosody by nine months (Jusczyk et al. 1992); Jusczyk interprets this pattern as

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evidenceof infants' exploitation of utterance prosody to structure speechinto interpretable units. Indirect evidencefor the present proposal can be found in both perceptual and production evidencefrom prelinguistic infants. For instance, it has been shown that the characteristic rhythmic pattern of speech is salient to the newborn child. Condon and Sander ( 1974) found that neonatesare able to synchronise their movements with speech structure, whether the speech is spoken directly to the child or played from a tape recorder, and whether it is in the parental languageor a foreign language. ( Tapping sounds, on the other hand, did not invoke synchrony in the infant ' s movement.) The ability to discriminate the contrasts involved in rhythmic patterning appearsearly ; thus two-month-olds can discriminate rhythmic groupings of tones (Demany et ale 1977) . These early discriminatory abilities also apply to the particular contrasts involved in speech rhythm : very young infants can discriminate stresscontrasts (Spring and Dale 1977, Jusczyk and Thompson 1978, Karzon 1985), and neonatescan make discriminations based on number of syllables (Bijeljac-Babic et ale 1993) . Speech to infants tends to have more regular rhythm than speech to adults, as evidenced in English by more frequent occurrenceof stresses (Garnica 1977) and more regular alternation of vocalisation and pause (Stem et ale 1983); however, the relevanceof this is unclear given that durational features of infant -directed speechdo not appear to be involved in infant preferencesfor this speechstyle (Fernald and Kuhl 1987) . More important would seemto be recent evidenceof rhythmic patterning in the speechproduction of prelinguistic infants. Cross-linguistic studies of babbling have pointed to increasing language-specificity in babbling during the secondhalf of the first year of life (e.g. de Boysson- Bardies et al 1984, de Boysson-Bardies and Vihman 1991, Halle et ale 1991, Blake and de BoyssonBardies 1992), including language-specificity in prosodic structure (Whalen et ale 1991) . Rhythmic structure is one of the language-specific patterns which appear in speechat this age. Levitt and Wang ( 1991) and Levitt and Utman ( 1992) found that reduplicative babbling of infants from French-speaking homes showed a gradually increasing regularity of timing of non-final syllables across the first year of life , while the speechof infants of the same age from English-speaking homes showed a gradually increasing variability of syllable structure and timing . This suggeststhat the characteristic rhythm of ' speechis incorporated into infants linguistic competencebefore they acquire their first words. It appears that infants also become aware of the characteristic word prosody of their language before acquiring their first words. Jusczyk et ale

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( 1993) found that nine-month -old infants acquiring English preferred to listen to lists of bisyllabic words with initial stress (crossing, former , cab/e) than bisyllables with final stress (across, before, decay), although no such preferences appeared with six-month-olds. Even when the lists were low-pass filtered to remove most of the segmental information , nine-month -olds still preferred the initial -stress lists, suggestingthat their preferenceswere based on prosodic structure. Jusczyk et ale argued that during the second half of their first year, infants exercisetheir ability to segmentspeechwith the result that they acquire knowledge of the typical prosodic structure of words in the input language. At later ages, language-specific exploitation of rhythmic structure by children is established: children learning English use stressrhythm in segmentation (Gerken 1991, Gerken et ale 1990, Peters 1985) ; children learning French and other languageswith syllable rhythm use syllables (Alegria et ale 1982, Content et ale 1986) ; children learning Japanese use morae (Mann 1986). The hypothesis proposed here is that language rhythm is also what allows infants to accomplish their very first segmentation of speech. An ability to processrhythm is inborn . By using this ability , infants are enabled to overcomethe segmentationproblem and hencetake their first step towards compilation of their very own lexicon.

References . Phoneticanalysisof speechand memorycodesin Alegria, J., E. Pignotand J. Morals, 1982 . Memoryand Cognition10, 451- 456. beginningreaders . The unintelligibilityof speechto children. Journalof Child Bard, E.G. and A. Anderson , 1983 . 10 265 292 , , Language Bard, E.G. andA. Anderson . The unintelligibilityof speechto children: Effectsof referent , 1991 of the Twelfth InternationalCongressof PhoneticSciences , Aix-enProvence availability. Proceedings , Vol. 4, 458- 461. Bard, E.G., R.C. Shillcockand G. Altmann, 1988.The recognitionof wordsafter their acoustic 44, offsetsin spontaneous : Effectsof subsequent context. Perceptionand Psychophysics speech 395- 408. . Cross-linguisticstudyof temporalcharacteristics Barik, H.C., 1977 of differenttypesof speech materials . Languageand Speech20, 116- 126. -Ratner, N., 1984a Bernstein . Patternsof vowelmodificationin mother-child speech . Journalof Child Language11, 557- 578. -Ratner, N., 1984b Bernstein . Phonologicalrule usagein mother-child speech . Journalof Phone tics 12, 245-254. -Ratner, N. and C. Pye, 1984 . Higher pitch in BT is nOI universal: Acousticevidence Bernstein from QuicheMayan. Journalof Child Language11, 515- 522.

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. How do 4- day-old infants categorize Bijeljac-Babic, R., J. Bertonciniand J. Mehler, 1993 ? Developmental multisyllabicutterances Psychology29, 711- 721. -Bardies Blake, J. and B. de Boysson . Patternsin babbling: A cross-linguisticstudy. Journal , 1992 of Child Language19, 51- 74. Blaauw, E., 1991. Phoneticcharacteristics of spontaneous and read-aloud speech . Proceedings of the ESCAWorkshopon Phoneticsand Phonologyof SpeakingStyles, Barcelona , 12.112.5. -Bardies de Boysson . Adaptation to language : Evidencefrom , B. and M.M. Vihman, 1991 and first wordsin four languages . Language67, 297- 319. babbling -Bardies de Boysson . Discernibledifferences in the babblingof , B., L. SagartandC. Durand, 1984 infantsaccordingto targetlanguage . Journalof Child LanguageII , 1- 15. Briscoe . Lexical accessin connectedspeechrecognition . Proceedings of the 27th , E.J., 1989 , Associationfor ComputationalLinguistics , Vancouver , 84- 90. Congress Brown, G., 1977 . Listeningto spokenEnglish. London: Longman. Brown, G.D.A., 1984. A frequencycount of 190,000 words in the London-Lund corpusof . BehaviorResearch Methods, Instrumentationand Computers16, 502Englishconversation 532. Brown, R., 1977 . Introduction. In: C.E. Snow, C.A. Ferguson(eds.), Talking to children: : CambridgeUniversityPress . , 1- 27. Cambridge Languageinput and acquisition Cheshire . Variationin an Englishdialect. Cambridge : CambridgeUniversityPress . , J., 1982 Cole, R.A. and J. Jakimik, 1978 . Understanding : How wordsare heard. In: G. Underwood speech of informationprocessing . , 67- 116. London: AcademicPress (ed.), Strategies . A methodfor the measurement Colombo, J. and R. Bundy, 1981 of infant auditoryselectivity . Infant Behaviorand Development , 4, 219- 233. . The MRC psycholinguistic Coltheart, M., 1981 database . QuarterlyJournalof Experimental Psychology33A, 497- 505. . Synchronydemonstratedbetweenmovementof the Condon, W.S. and L.W. Sander , 1974 . Child Development neonateand adult speech 45, 456- 462. Content, A., R. Kolinsky, J. MoralsandP. Bertelson . Phoneticsegmentation in prereaders : , 1986 Effectof correctiveinformation. Journalof ExperimentalChild Psychology 42, 49- 72. . InvestigatingEnglishstyle. London: Longman. CrystalD . and D. Davy, 1969 . Rhythmiccues to speechsegmentation : Evidencefrom Cutler, A. and S. Butterfield, 1992 . Journalof Memoryand Language31, 218- 236. juncturemisperception . The predominance Cutler, A. and DiM . Carter, 1987 of stronginitial syllablesin the English . ComputerSpeechand Language2, 133- 142. vocabulary . The recognitionof lexicalunits in speech . In: B. de Cutler, A. and JiM. McQueen , in press . Cambridge . Gelder, J. Morals(eds.), From spokento written language , MA : MIT Press . The periodicitybias. Journalof Phonetics21, 103- 108. Cutler, A. and J. Mehler, 1993 . The role of strongsyllablesin segmentation . for lexicalaccess Cutler, A. and DiG. Norris, 1988 : HumanPerceptionand Performance 14, 113- 121. Journalof ExperimentalPsychology 's . The syllable Cutler, A., J. Mehler, D.G. Norris and J. Segui, 1986 differing role in the . of of French and Journal and Memory segmentation English Language25, 385- 400. . The monolingualnature of speech Cutler, A., J. Mehler, D. Norris and J. Segui, 1992 24, 381- 410. segmentation by bilinguals. CognitivePsychology . Rhythmperceptionin early infancy. Nature , L., B. McKenzieand E. Vurpillot, 1977 Demany 266, 718- 719.

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. The time courseof lexicalprocessing : The syllabichypothesisrevisited . In: Dupoux, E., 1993 G.T.M. Altmann, R.C. Shillcock(eds.), Cognitivemodelsof speechprocessing : The Sperlonga . MeetingII , 81- 114. CambridgeMA : MIT Press . Monitoring the lexiconwith normal and compressed : Dupoux, E. and J. Mehler, 1990 speech Frequencyeffectsand the prelexicalcode. Journalof Memoryand Language29, 316- 335. . Baby talk as a simplifiedregister . In : C.E. Snow, C.A. Ferguson(eds.), , C., 1977 Ferguson : CambridgeUniversity , 209-235. Cambridge Talkingto children: Language input andacquisition Press . Fernald, A., 1985 . Four-month-old infants prefer to listen to motherese . Infant Behaviorand 8, 181- 195. Development Fernald, A. and P. Kuhl, 1987 . Acousticdetenninantsof infant preference for motheresespeech . Infant Behaviorand Development10, 279- 293. ' Fernald, A. andT. Simon, 1984 . Expandedintonationcontoursin mothers . speechto newborns 20, 104- 113. Developmental Psychology -Bardiesand I. Furui, 1989 Fernald, A., T. Taeschner .A , J. Dunn, M. Papousek , B. de Boysson ' and fathers' cross-languagestudy of prosodicmodificationsin mothers speechto preverbal infants. Journalof Child Language16, 477- 501. Garnica, 0 ., 1977 . Someprosodicand paralinguisticfeaturesof speechto youngchildren. In: C.E. Snow, C.A. Ferguson(eds.), Talkingto children: Languageinput and acquisition , 63- 88. : . Press CambridgeCambridgeUniversity Gerken, L., 1991 . The metricalbasisfor children's subjectless sentences . Journalof Memoryand Language30, 431- 451. Gerken, L., B. Landauand R.E. Remez . Functionmorphemes in youngchildren's speech , 1990 . and 26 204 216 . , perception production Developmental Psychology Gleitman, L.R. and E. Wanner, 1982.Languageacquisition:The stateof the stateof the art. In: E. Wanner, L.R. Gleitman(eds.), Language : acquisition:Thestateof theart, 3- 48. Cambridge . CambridgeUniversityPress Gleitman, L.R., H. Gleitman, B. Landauand E. Wanner, 1987 . Wherelearningbegins: Initial for languagelearning.In: F. Newmeyer(ed.), TheCambridgelinguisticsurvey, representations : CambridgeUniversityPress 150- 193. Cambridge . Glenn, S.M., C.C. Cunningham and P.F. Joyce, 1981 . A study of auditory preferences in ' nonhandicap . Child Development52, 1303 ped infants and infants with Downs Syndrome . 1307 Grieser . Maternalspeechto infantsin a tonal language : Supportfor , D.L. and P.K. Kuhl, 1988 universalprosodicfeaturesin motherese . Developmental Psychology24, 14- 20. . The recognitionof wordsafter their acousticoffset: Evidenceand implications , F., 1985 Grosjean . Perceptionand Psychophysics 38, 299- 310. -Bardiesand M.M. Vihman, 1991 Halle, P., B. de Boysson . Beginnings of prosodicorganisation : Intonation and duration patternsof disyllablesproducedby Japanese and Frenchinfants. Languageand Speech34, 299- 318. . The applicationof phonemesequence Harrington, J.M., I. Johnsonand M. Cooper, 1987 constraintsto word boundaryidentificationin automatic . , continuousspeechrecognition of the First EuropeanConference on Speech , Edinburgh,Vol. I , 163Proceedings Technology 167. Harrington, J.M., G. Watsonand M. Cooper, 1989.Word boundarydetectionin broadclassand phonemestrings. ComputerSpeechand Language3, 367- 382.

A. CutlerI Segmentation problems . Experimentson the segmentation of an artificial speech Hayes, J.R. and H.H. Clark, 1970 . In : J.R. Hayes(Ed.), Cognitionand the developmentof language , 221- 234. New analogue York: Wiley. Heath, S.B., 1983 . Wayswith words: Language . , life and work in communitiesand classrooms : CambridgeUnivenity Press . Cambridge Hirsch-Pasek , K., D.G. KemlerNelson, P.W. Jusczyk , , K.W. Cassidy , B. Drussand L. Kennedy . Clausesare perceptualunits for younginfants. Cognition26, 269- 286. 1987 . Prosodicdifferentiationof discoursemodes Johns-Lewis, C., 1986 . In: C. Johns-Lewis (ed.), Intonationand discourse , 199-219. London: CroomHelm. Johns-Lewis, C., 1987 . The perceptionof discorusemodes . In: M. Coulthard(ed.), Discussing discourse . Universityof Binningham: DiscourseAnalysisResearch MonographNo. 14, 249271. . How word recognitionmay evolvefrom infant speechrecognitioncapaci, P.W., 1993 Jusczyk : The tien. In: G.TiM. Altmann, R.C. Shillcock(eds.), Cognitivemodelsof speechprocessing . SperlongaMeetingII , 27- 55. CambridgeMA : MIT Press . Perceptionof a phoneticcontrast in multisyllabic , P.W. and E. Thompson , 1978 Jusczyk utterances 23, 105- 109. by,2-month-old infants. Perceptionand Psychophysics . Infants' preference for the predominantstress , P.W., A. Cutler and N.J. Redanz , 1993 Jusczyk . 64 675 687 . of words Child , Development patterns English , L. Kennedy , A. Woodwardand J. Piwoz, , P.W., DiG. KemlerNelson, K. Hirsch-Pasek Jusczyk . Perceptionof acousticcorrelatesof major phrasalunits by young infants. Cognitive 1992 24, 252- 293. Psychology . Discriminationof polysyllabicsequences Karzon, R.G., 1985 by one- to four-month-old infants. . Journalof ExperimentalChild Psychology39, 326- 342 . In: W.D. Manlen-Wilson . Reviewof selectedmodelsof speechperception Klatt, D.H., 1989 . and process , MA : MIT Press , 169-226. Cambridge (ed.), Lexicalrepresentation of readingaloud . Temporalaspects Kowal, S., D. O' Connell, E. A. O' Brienand ET . Bryant, 1975 88, 549- 569. : Threeexperiments . AmericanJournalof Psychology and speaking . Linguistic Kuhl, P.K., K.A. Williams, F. Lacerda , K.N. Stevensand B. Lindblom, 1992 255, 606- 608. alten phoneticperceptionin infantsby six monthsof age. Science experience Press . . Sociolinguistic Labov, W., 1972 , PA : UDiversityof Pennsylvania patterns.Philadelphia within wordsand acrossword . Propertiesof consonantsequences Lamel, L. andV.W. Zue, 1984 and Signal on Acoustics . Proceedings of the 1984InternationalConference boundaries , Speech 42.3.4. 42.3.1 Processing . Theprosodicand paralinguisticfeaturesof reading Levin, H., Schaffer , C.A. andC. Snow, 1982 and tellingstories. Languageand Speech25, 43- 54. of Englishand . From babblingtowardsthe soundsystems Levitt, A.G. and JiG.A. Utman, 1992 French: A longitudinaltwo-casestudy. Journalof Child Language19, 19- 49. . Evidencefor language Levitt, A.G. and Q. Wang, 1991 -specificrhythmic influencesin the . Languageand Speech34, 235infants and of French learning English babbling reduplicative 249. . Someeffectsof semanticand grannnaticalcontexton the productionand Lieberman , P., 1963 . Languageand Speech6, 172- 187. of perception speech . . A computationalanalysisof uniqueness Luce, P.A., 1986 pointsin auditoryword recognition 39, 155- 158. Perceptionand Psychophysics . Cognition24, 65-92. : Therole of readingexperience . Phonological awareness Mann, V.A., 1986

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. of lexicallystreSsed . Theprocessing speech McAllister, J., 1991 syllablesin readandspontaneous 1 26 . 34 Languageand Speech , . . Wordswithin words: Lexicalstatisticsand lexicalaccess , J.M. and A. Cutler, 1992 McQueen on SpokenLanguageProcessing , Banff, of the SecondInternationalConference Proceedings Canada , Vol. I , 221- 224. . PhilosophicalTransactionsof the . The role of syllablesin speechprocessing Mehler, J., 1981 , B295, 333- 352. RoyalSociety : The onsetof . Constrainingmodelsof lexicalaccess Mehler, J., E. Dupouxand J. Segui, 1990 : Psycholinguistic . In: G.TiM. Altmann(ed.), Cognitivemodelsof speechprocessing word recognition . , MA : MIT Press and computationalperspectives , 236- 262. Cambridge ' and J. Segui , 1981.The syllables role in speech Mehler, J., J.-Y. Dommergues , U. Frauenfelder . Journalof VerbalLearningand VerbalBehavior20, 298- 305. segmentation . and readspeech in spontaneous . Detectionof targetphonemes Mehta, G. and A. Cutler, 1988 . 156 31 135 and Language Speech , . . London: Penguin . The psychologyof communication Miller, G.A., 1967 . . Languageand socialnetworks.Oxford: Blackwell Milroy, L., 1980 . Cr,?ss-languageuseof pitch: An ethologicalview. Phonetica40, 1- 18. Ohala, J.J., 1983 . An ethologicalperspectiveon commoncross-languageutilization of FO of Ohala, J.J., 1984 voice. Phonetica41, 1- 16. . . Paperpresentedto the of Japanese . Morae and syllablesin the segmentation Otake, T., 1992 of Psychology , July. XXV InternationalCongress , Brussels in . Mora or syllable? Speechsegmentation Otake, T., G. Hatano, A. Cutlerand J. Mehler, 1993 378 . 358 32 and of . Journal , Language Memory Japanese : Operatingprinciplesfor the perceptionand analysis . Languagesegmentation Peters , A.M., 1985 , Vol. 2: . In: D.I Slobin (ed.), The crosslinguisticstudy of languageacquisition of language . Erlbaum NJ: Hillsdale . 1029 1067 Theoreti~ 1issues , , . Babbling in the manual mode: Evidencefor the Pettito, L.A. and P.F. Marentette , 1991 - 1496. . Science251, 1493 ontogenyof language . Journal of Psycholinguistic of speechin a foreign language . Segmentation Pilon, R., 1981 Research10, 113- 122. utterancesand intonationin spontaneous . Sentence Remez , R.E., PiE. Rubin and S. Ball, 1985 l09th of America Acoustical to the , Meeting, text. Society Paperpresented fluently spoken Austin, Texas, April. . The acquisitionof Kaluli. In: D.I. Siobin(ed.), The crosslinguisticstudy Schieffelin , B.B., 1985 of languageacquisition , Vol. 1: The data, 525- 593. Hilisdale, NJ: Erlbaum. on the transitionfrom prelinguisticto . A culturalperspective Schieffelin , B.B. and E. Ochs, 1983 The transition from prelinguisticto ed. R.M. Golinkoff . In: ( ), linguistic communication . : Erlbaum . London 131 115 communication , linguistic . In : H. Bouma, Segui, J., 1984. The syllable: A basic perceptualunit in speechprocessing . Hillsdale, NJ: 165 181 10 Vol. and . Attention , , D.G. Bouwhuis (eds), performance Erlbaum. . Phonememonitoring, syllablemonitoringand , J., U. Frauenfelderand J. Mehler, 1981 Segui 72 of . BritishJournal Psychology , 471- 477. lexicalaccess . Someprosodiceffectson human word . G. Bard and F. Spensley , 1988 Shillcock, R.CE of SPEECH' 88 (SeventhSymposiumof the . Proceedings recognitionin continuousspeech of Europe), Edinburgh, 819- 826. Federationof AcousticSocieties

A. Cutler/ Segmentation problems . Propertiesof large lexicons: Implicationsfor advanced , D.W. and V.W. Zue, 1982 Shipman isolatedword recognitionsystems . Proceedings of the 1982InternationalConferenceon Acoustics , Speechand SignalProcessing , Paris, 546- 549. . Phonologicalprocess , L. and Z.S. Bond, 1980 es in speechaddressedto children. Shockey Phonetica37, 267- 274. Shute, H.B., 1987 . Vocalpitch in motherese . EducationalPsychology 7, 187-205. . Discriminationof linguisticstressin earlyinfancy. Journalof SpringD .R. and P.S. Dale, 1977 20, 224- 232. Speechand HearingResearch Stem, D.N. S. Spieker . The prosodyof maternalspeech , R.K. Barnettand K. MacKain, 1983 : Infant ageand context-relatedchanges . Journalof Child Language10, 1- 15. Stoel-Gammon,C., 1984 . Phonological . Phonetica41, 208- 214. variabilityin mother-childspeech Sullivan,J.W. and F.D. Horowitz, 1983 . Theeffectsof intonationon infant attention: Theroleof the risingintonationcontour. Journalof Child Language10, 521- 534. Svartvik, J. and R. Quirk, 1980 . A corpusof Englishconversation . Lund: Gleerup. . The babblingof a Thai baby: Echoesand responses , P., 1978 Tuaycharoen to the soundsmade . by adults. In : N. Waterson , C. Snow(eds.), The developmentof communication , 111- 125. Chichester : ~ iley. Wakefield , J.A., E.B. Doughtie and B.-H.L. Yom, 1974 . The identificationof structural in an unknownlanguage . Journalof Psycholinguistic components Research 3, 261- 269. Werker, J.F. and L. Polka, 1993 . Developmental : New challenges changesin speechperception and newdirections . Journalof Phonetics21, 83- 101. Wexier, K. and R. ManziniParameters and learnabilityin bindingtheory. In: T. Roeper , E. Williams(eds.), Parametersetting, 41- 76. Dordrecht: Reidel. Whalen, D.H., A.G. Levitt and Q. Wang, 1991 . Intonationaldifferences betweenthe reduplicative babblingof French- and English-learninginfants. Journalof Child Language18, 501- 516. Wilso~, M.D., 1988 . MRC psycholinguistic database : Machine-usabledictionary, Version2.0. BehaviorResearch Methods, Instrumentationand Computers20, 6- 10.

) 105- 140. North-Holland Lingua92 ( 1994

Domain -general abilities applied to domain -specific tasks: Sensiti vi ty to probabilities in perception , cognition , and * language Michael H . Kelly and Susanne Martin , Philadelphia , PA , 3815WalnutStreet , University of Pennsylvania Department of Psychology -6196 19104 . USA Perceptual and cognitive abilities that are species- and domain-specific may nonethelesshave componentsthat are widespreadacrossspeciesand apply to numerousdomains. For example, all theories of sentenceparsing are constrained by the operations of a limited -capacity memory that is a generalcharacteristic of cognition . This paper discussesanother ability that is general across speciesand, within a species, across numerous cognitive and perceptual domains. We review evidencefrom the animalleaming and human cognitive literature that animals (a) possessfinegrained sensitivity to probabilistic patterns in their environment and (b) usemultiple probabilistic cues to solye particular problems. Such sensitivity is advantageousbecausethe structure of the environment itself can often be characterized as probabilistic . The chancesof successat solving various problems, from foraging to depth perception, would therefore increaseif animals were sensitiveto probabilistic cues and could determine whether multiple cuesconvergeon a solution. We discussthe implications of theseclaims for languageprocessing, and argue that the domaingeneral ability to detect and exploit probabilistic information is brought to bear on numerous language-specific problems.

1. Introduction

A common theme in evolutionary biology concernsthe distinction between inherited and specific adaptations. Both structures may aid an organism, but ' the former derive from the organism s ancestry whereas the latter may have evolved to suit its specific needs. Consider the duck-billed platypus, for example. These strangest of all mammals possess numerous anatomical . Preparationof this paper was supportedby National Institutesof Health Grant I R29 Mehler, and Bob Rescoriafor helpful HD23385to M.H. Kelly. Thanksto AnneCutler, Jacques commentson earlierversionsof this paper. - 3841/94/507.00 @ 1994- ElsevierScienceB.V. All rightsreserved 0024

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structures that assist their aquatic lifestyle. Thus, waterproof fur helps to insulate the platypus from the cold waters in which it normally swims and its famous bill is actually a highly-developedsenseorgan that is used in foraging. However, the history of these two adaptations is quite different. Whereas the bill seems to be a specific adaptation of the platypus and monotreme relatives, the fur , of course, is a general mammalian trait that the platypus inherits (seeGould , 1991, for further discussion). This trait is general in two ways. First , many speciesshare it and, second, it is relatively general purpose. Thus hair is not only involved in insulation, but also in sensationsof touch and the transduction of sound in the inner ear. As Darwin emphasized in many of his works, the same evolutionary concepts that apply to anatomical structures can also extend to thought and behavior. Thus, some of our own cognitive and perceptual abilities are inherited from our ancestors(and henceit is no coincidencethat we can learn something about, for instance, our visual system by studying the visual systemsof other animals - they are branches from the same tree) . Still other structures might be unique to the evolutionary history of human beings. Language is, of course, the most obvious human duck-bill , and much ink has been spilled over the years in arguments over whether this obvious intuition should really be believed. That controversy will be avoided here. Instead, we will focus on the following general theme: Whatever the evolutionary history of the language faculty , language processing must involve cognitive and perceptual abilities that are domain-general in nature. For an example, consider the parsing literature. Both linguists (e.g., Frazier and Fodor 1978) and psychologists (e.g., Just and Carpenter 1992) have devoted considerable attention to how listeners identify sentenceconstituents and their grammatical relations. Radically different viewpoints are often proposed about how these tasks are accomplished. However, throughout all the controversy, one unifying point stands clear: The parser is fundamentally a slave to a limited capacity short-term (or working ) memory system. Thus, parsing preferences from Kimball ' s ( 1973) ' fast phrase closure' to Frazier and Fpdor ' s ( 1978) ' minimal attachment' are all justified by reference to constraints on shortterm memory capacity. Indeed, potential individual differences in parsing blaseshave recently been related to individual differencesin memory capacity (Just and Carpenter 1992) . In sum, then, a system that is shared by other animals, namely a limited capacity memory, is critically involved in a systemprobably unique to human beings, namely language. Furthermore, an understanding of this ancestral memory system is crucial to a full understanding of how linguistic compe-

M .H . Kelly , S. Martin / Domain-general abilities

tence gets put to use in perfonnance. Finally , since this ancestral system is shared with our non-human relatives, we could gain insights into the human systemthrough memory experimentswith animals as well as experimentswith human beings. We will extend these claims here to another domain potentially shared with non-human animals. This domain is reflected in the old adage that death and taxes are the only certainties in life. In less depressing tenDs, much of the information that animals learn during their lives, and which must be used to guide behavior, is probabilistic in nature. Should the human being bet on the Flyers to win the NHL championship now that they have signed the Michael Jordan of hockey in Eric Lindros ? Is the breeding seasonpromising enough for a bird to raise two clutches of young rather than just one? Will the squirrel find more nuts foraging by this tree or that one? Should a listener who hears ' The fruit flies ...' assumethat ' fruit ' is a noun and ' flies' is a verb? Though these questions vary in their subject matter and importance, they all nonethelesscontain some level of uncertainty, and the types of information that could be used to decide a course of action are probabilistic in nature. Historically , attention to probabilities and their use has been either ignored or looked upon with aversion bordering on plain disgust. Thus, mathematical treatments of probability are relatively recent developments, and were fonnulated in the dubious area of gambling. Even physics, the ' paragon of scientific certainty, has not escapedfrom the clutches of probability , and the probabilistic component inherent to quantum mechanicsdrove Einstein to exclaim that God could simply NOT be a closet gambler. One possible reason for negative views of probability could be an implication that the world is full of mass confusion that cannot lead to anything ' beyond ignorance. However, an animal s environment is not a homogeneous ' ' soup, although it rarely provides sure things . The basic fact of the matter is that the world is awash with stuff best described as ' tendencies', ' maybes', ' estimates' and ' ' , generally-speakings. Furthermore, thesetenDs characterizea wide array of domains, from foraging to parsing, and must be confronted by creatures from aardvarks to zebus. Finally , animals must often make rapid decisions while minimizing the likelihood and severity of errors. These considerations lead to the following conclusion: Animals that have the capacity to detect probabilistic patterns and exploit them will have an advantageover those that do not. Furthermore, confidencein the solution to a problem should increaseif multiple cues converge on that solution. Hence, one might expect to see widespread sensitivity to multiple probabilistic infonnation sources in the animal kingdom . Since many aspects of the

-generalabilities M.H. Kelly, S. Marlin I Domain

environment are characterizedby probabilistic relations among variables, one would also expect this sensitivity to be relatively domain-independent. Indeed, such sensitivity might permeate the activities of specializedabilities, including language. In the remainder of this paper, we will attempt to justify these claims. We will begin by highlighting some phenomena in the area of animal learning and cognition that support the view, perhaps surprising, that rather precise sensitivity to probabilistic information is prevalent in many species. In fact, it seemsto be a rather everyday, ho-hum ability . We will then turn to human perception and cognition , and review some evidencein nonlinguistic domains suggestingthat , like rats, human beings exploit probabilistic information in a variety of tasks. Furthermore, even when sufficient information exists to apparently deduce the solution to a problem, human beings still use additional , probabilistic information that might also be present. We will discuss some of the possible advantages to this strategy. Finally , we will summarize evidencefrom the domain of languageprocessing that also supports widespread sensitivity to probabilistic relations among linguistic variables, as well as the types of tasks that could be assisted by exploiting this information . The researchhere will suggestthat , just as human memory is critically involved in areas ranging from visual pattern recognition to parsing, so the ability to learn and exploit probabilistic information is widespreadin perception and cognition, including traits that might be highly specializedand species-specific. 2. The ' statistical ' rat

Since the cognitive revolution , the once dominant area of animal learning has become of peripheral interest to many experimental psychologists. This major shift of both theoretical and experimental emphasiscould be attributed to a variety of factors, ranging from the development of symbolic computing devices to Chomsky' s critique of stimulus- response accounts of language. Hence, in the cognitive sciencesin general, and languagestudies in particular , traditional investigations of animal learning and their possible implications for human cognition have been virtually , if not completely, ignored. (For some recent exceptions, see Alloy and Tabachnik 1984, Estes 1985, Gluck and Bower 1988.) We believe that this abandonment of animal learning is a sad state of affairs. Certain basic processes of learning are clearly homologous across speciesranging from insects to human beings, and suciJ universality should hardly be of peripheral interest to cognitive scientists. Our

M .H . Kelly , S. Martin I Domain-general abilities

purpose here is not , however, to instigate a general rapprochement between divorced parties. Rather, we will attempt to direct attention to certain fundamental abilities that animals apparently must possessin order to behave the way they do in learning experiments. These abilities can be characterized as a keen sensitivity to the rate at which certain probabilistic events occur in the animal' s environment. 2.1. Behavioral decisionsbasedon detectionof rate information Consider the following situation : On each of a series of trials , a rat is placed in the long axis of a T -shaped maze. If the rat traverses down the correct arm of the T , it will receivea morsel of food as a reward. The correct arm varies from trial to trial , but the right arm is biased to be correct 70% of the time, with the left arm correct 30% of the time. Across a wide range of studies, the results of this situation are clear: The rat will distribute its choices in accord with the particular probabilistic bias establishedby the experimenter . In this case, the rat will travel down the right arm 70% of the time and the left arm 30% of the time. If the probabilities changeto , say, 85- 15 or 6040, then the rat ' s choices will adjust accordingly. The rat ' s behavior reveals precisesensitivity to the rate of reward in the two arms (seeGallistel, 1990, for more extensivediscussion) . ' Despite this sensitivity to rate information , the rat s behavior in this paradigm seemsparadoxical. After all , in order to optimize its food intake, the rat should always choose the side with the higher rate of return. 1 Although this conclusion is true in the laboratory , where the animal facesno competition for the food resource, it is not true in the wild . Supposethat two food patchesexist in a local habitat , with one of them being twice as rich as the other. If all of the animals went to the richer patch, then selection pressureswould favor animals who would exploit the food -poor , but competitorless patch. Evolutionary biologists have argued that , in the long run , the most stable evolutionary strategy would involve dividing one' s time between the two food patchesin accord with their rates of return. Investigations of the spatial distributions of animals while foraging indicates that this strategy is indeed used in the natural environment (seeGallistel , 1990, for summary) . Of course, as Gallistel emphasizes , this strategy presumesthe ability to detect the I For instance, supposethat the probability of reward on the right arm is 75%. In 100trials , the rat on averagewould receivea reward on O.75( 100) + 0.25(0), or 75, of the trials if it always chose the right arm. If it choosesthe arms in accord with their reward probabilities, then the rat can expect reward on 0.75(75) + 0.25(25), or only 62.5 of the trials.

M .H . Kelly , S. Martin I Domain-general abilities

rate of food return in different parts of the environment. Both laboratory studiesand natural observations indicate that a range of species, such as rats, pigeons, ducks, and fish possessthis ability . This sensitivity to probabilistic patterns reveals itself in a variety of behaviors besides the choice of where a food resource might be located. .Furthermore, the pervasivenessof this sensitivity across speciesis shown by the fact that different speciesproduce analogous results in the same task. Consider, for example, the speedwith which an action is performed after a stimulus is perceived. Gradual increasesin the likelihood of a certain event leads to corresponding decreasesin the time neededto react to that event. A notable example in the field of language researchis the inverse relationship between word frequency and the reaction time needed to make judgments about a word. However, numerous events vary in their frequency of occurrence, and animals generally become faster at reacting to more frequent events. Indeed, procedures have been developed to test human beings and other animals in very similar circumstances, and the relationship between frequency of an event and speedof responseis virtually identical across the speciesgroups (Pang et al. 1992) . Such results clearly imply that (a) a learning mechanism exists that permits adaptive adjustments to the likelihoods of different events, (b) the mechanism is domain-general in that it appears for -general, and numerous eventsand behaviors, and (c) the mechanismis species so representsa basic aspect of animal learning, including learning by human beings. 2.2. Catching the contingencies

In the famous learning experiments conducted by Ivan Pavlov, a dog was presented with a neutral stimulus, such as a tone, paired with food. As a result of these pairings, the dog began to salivate when the tone was presentedalone. In the technical terms of the field, an unconditioned stimulus (US), the food , normally elicits an innate unconditioned response (UR ), salivation. By pairing the tone with the food , the former becomesa conditioned stimulus (CS) that produces a conditioned response(CR ), in this case salivation. Thousands of subsequentexperiments, involving a huge assortment of stimuli , responses , and specieshave verified that this type of learning is quite basic throughout the animal kingdom . Extensiveresearchhas tried to understand the mechanismsthat are responsible for learning in the Pavlovian paradigm. We will focus here on one theme that has emergedfrom this research. This theme is, in many ways, reflectedin

M .H . Kel/y , S. Martin I Domain-general abilities

the description of Pavlovian conditioning with which we opened this section. This description, which is commonly used in introductory psychology texts, assumesthat learning dependson explicit pairings betweenan unconditioned stimulus and a conditioned stimulus. Various predictions follow from this assumption. Thus, learning should increase with the number of CS-US pairings, and learning should not occur in the absence of such pairings. However, as Rescorl.a ( 1988) has emphasized, this assumption and its empirical consequencesare untrue. Under certain conditions, even multiple pairings of a CS and US will not causethe animal to assumethat the CS predicts the US. On the other hand, learning can be achieved without a single CS-US pairing . Thus, CS-US pairings are neither sufficient nor necessaryto produce learning. These facts, and the conditions that create them, have led to major revisions in learning theory over the past two decades, and indicate that animals have far more sophisticated learning abilities than were previously imagined. In a series of classic experiments, Rescoria ( 1968) demonstrated that animals are sensitivenot to the raw frequency of CS-US pairings, but rather the general contingency between the variables. In his studies, rats were first trained to press a bar for food. In the next phase, the animals received a number of pairings betweena tone and a mild electric shock. To measurethe extent of learning, the rats were then permit ted to press the food bar once again. During this period, the tone was occasionally presented, and the animal' s behavior monitored. If the animals learned that the tone signals shock, they would decreasetheir levels of bar pressingand hold a motionless posture. Slight levels of learning would produce slight decreasesin the rates of bar pressingwhereashigher levels of learning would produce correspondingly greater suppressionof the bar presses. The critical manipulation in the experiments concerned the likelihood that the shocks in the second phase occurred in the absence of the tone. That is, in addition to the explicit pairings between the tone and shock, a number of other shocks could be administered without a corresponding tone. Traditional learning theory would predict that these additional unpaired shocks would be irrelevant to the learning process since the number of US-CS pairs would be unaltered. However, instead of responding just to explicit pairings of the CS and US, supposethat the rat is sensitiveto the appearanceof the US in the absenceof the CS. If the animal can detect these general contingencies between the shock and tone, then the signaling power of the tone should decreaseas higher rates of independent shocks are encountered. Indeed, a certain point should be reached at which the shock and the tone are statistically indepen-

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dent. That is, given the overall base rate of shocks, one would expect a certain number of tone-shock pairs JUST BY CHANCE . Given that such encountersare mere coincidences, one should make no conclusion about the relevanceof the tone to the shock, and hence the tone should be ignored in the final test phase. Rescorla's results strongly supported the contingency interpretation of learning. As the predictive power of the CS dropped, so did the effectsof the tone on the rats' bar pressing. When the tone and the shock reached statistical independence , the presenceof the tone had no effect on behavior. In sum, Rescorla' s experiments refute the traditional belief, and one still generally held outside of the animal learning field, that the number of CS-US pairings is the crucial variable in learning. Rather, animals are sensitiveto the statistical relationship between the variables. If no statistical relationship exists, then even the presenceof numerous CS-US pairings will not causethe animal to assume that the CS predicts the US. Furthermore, statistical relationships can exist and be learned even in the absence of any CS-US ' pairings. For instance, supposeRescorla s experiment is repeated, but with all of the scheduled tone-shock pairs removed. Thus, the rat would receive a number of shocks, but none accompaniedby the tone. Since no CS-US pairs are presented, the stereotyped view of Pavlovian conditioning would predict that the animal would learn no relation betweenthesevariables. However, the rats do in fact learn something useful in this situation , namely that the presenceof the tone predicts the absenceof the shock. Hence, the rats treat the tone as a safety signal and actually show lessfear reactions when the tone is present than when it is absent (Rescoria 1969) . So far , we have discussedsome evidence that animals are sensitive to the probabilistic relationship betweena single CS and a US. However, numerous experimentsdemonstrate that animals can attend to multiple predictors of an event. For example, suppose that an animal has learned that a tone and a light both signal shock. If the stimuli are now presentedtogether, then, up to a certain point , the animal will exhibit a stronger fear reaction to the joint ' than to the separatepresentation of the stimuli. 2 Thus, an animal s behavior Z The' up to a certainpoint' phraseturnsout to becrucial. If two stimuliarestronglypredictiveof another , canactuallyreduce , evenif coupledwith US presentation , thenrepeated joint presentations of theCSs. As Uebennan( 1990 thereactionto individualpresentations ) pointsout, this apparently . One might expectthat joint makessensefor the followingreason counterintuitive phenomenon the US or strengthof the US. If of an increased the CSs would of probability signal presentation . These are not confirmed theseexpectations , then they must be adjusteddownwardaccordingly of theCSs. in reactionsto theseparate canthenbe observed downwardadjustments presentations

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in a particular situation is best predicted by what it has learned about the set of informative cues present in its environment rather than any single cue examined in isolation. Indeed, what an animal learns about a novel stimulus will depend on what it has learned about other stimuli present at the same time. Consider, for example, the following situation. An animal learns that a tone is associatedwith a mild shock. After this relationship is established, the animal now is presentedwith two stimuli - the original tone and a novel light . No shocks are experiencedduring this phrase of compound stimulus presentation . Later, the light can be presented alone, and the animal' s behavior monitored to determine what , if anything, has been learned about the light . A number of possibilities are conceivable. Since the light was never experienced with the shock, one might expect that the former would later be perceivedas a neutral stimulus. Alternatively , some of the fear induced by the tone might spread to the light . However, the animal actually treats the light as a safety signal, and the strength of the safety reaction varies with the strength of the fear associatedwith the tone (seeRescoria and Wagner, 1972, for summary) . In learning about the impact of the light , the animal apparently takes into consideration its knowledge about the tone. Given that the latter normally signals shock, the absenceof the latter becomes associated with the novel ' light . As Rescoria and Wagner ( 1972: 73) state, The effect of a reinforcement or nonreinforcement in changing the associative strength of a stimulus depends-upon the existing associativestrength, not only of that stimulus, but also of other stimuli concurrently present' . In sum, then, numerous experiments in animal learning indicate (a) widespread sensitivity to probabilistic relations betweenevents and (b) the use of multiple cues in identifying the probable course of imminent events, and the types of behaviors neededto deal with them. Nonetheless, we must emphasize that even though animals behave in accordance with statistical patterns in their environment, this behavior does not lead to strong conclusions about the underlying mechanismsthat support it . Animals might reveal sensitivity to statistical patterns without actually representingor manipulating probabilistic data. For example, each learning trial could lead to the adjustment of the association strength between a CS and a US. This association strength would be increasedwhen the US appearswith the CS and decreasedwhen the US appears without the CS. Over time, the probability of a CS-US pairing would become more and more correlated with the association strength, though the probability itself would not be representedby the animal. Thus variations in the probabilities of different eventscould produce behavior that is attuned to those probabilities without entailing that these values are

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explicitly represented or that the animal even remembers each individual learning trial . In fact, the most influential model of Pavlovian conditioning over the past two decadesdoes reproduce apparent sensitivi~;Y to statistical patterns by using trial by trial updates of association strengths betweena US and potential CSs (Rescoria and Wagner 1972) . But regardlessof the exact nature of the mechanismsthat underlie it , animals clearly have evolved some form of sensitivity to probabilistic patterns in their environment, and this sensitivity is finely tuned to the actual probabilities of various events.

2.3. Someimplications for languagelearning Let us translate some of theseanimal learning studies into a more familiar setting, though with controversial implications. During languageacquisition, children must learn the subcategorization privileges of the verbs in their ' ' language. Thus, English children must learn that give can appear in both ' ' prepositional (e.g., John gave the money to the charity ) and double object ' ' ' dative structures (' John gave the charity the money ), but that donate can only appear in the prepositional form . How do children learn these relationships ? The ' give' caseseemsstraightforward in that the child will observe the ' verb in both structures and conclude that ' give is legal in those frames. Thus, the child makes conclusions based on positive evidence. However, caseslike ' donate' seemto create more problems for languageacquisition. One possibility is that general principles of learning could apply to the linguistic domain. ' ' Thus, if children get explicit reinforcement that donate is ungrammatical in the double object form , then such negative evidencecould help them to learn ' ' syntactic restrictions on donate . However, numerous studies have documented that children do not get such explicit negative evidence(see Pinker, 1989, for review) . Given the lack of reinforcement coupled with successful learning, the dominant conclusion has been that general principles of learning will not apply to languageacquisition. This argument rests on incorrect assumptions about current theoretical views in animal learning, or the experimentson which those views are based. As the preceding discussion has emphasized, animals can readily learn not only that tones predict the presenceof shock, but also that tones can predict the absenceof shock. They need no additional feedback for justification or refutation of their conclusions. If learning is considered, at least in part , as the detection of statistical regularities in the environment, then children might ' learn that ' donate systematically predicts the absenceof double-object structures in the same manner as rats can learn that tones systematically predict

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the absence of shocks. Just as a species-general memory system can be -general learning abilities, in critically involved in languageparsing, so species this casethe ability to detect the statistical texture of the environment, could be involved in languagelearning. Referencesto statiscial sensitivity have recently grown in critiques of the negative evidence problem (e.g., Liberman 1991). However, we believe that prima facie incredulity over the potential of this approach, or even the mere existenceof the statistical sensitivity, would decline if animal learning studies such as those reviewedabove were more seriously consideredin discussionsof language learning. The evidence from the animal literature is now quite conclusive in that speciesafter specieshas been found not only sensitive to probabilistic information , but even to the precise quantitative nature of this information (bearing in mind once again that the exact mechanismsresponsible for this sensitivity must be identified) . Furthermore, they show such sensitivity in a variety of learning situations that use quite arbitrary stimuli , suggestingthat the ability is domain-general, and not tied to information that the animal is biologically prepared to learn. 2.4. Objections

Numerous objections could, of course, be raised against the conjectureswe have just made. We do not pretend to have definitive answers to these problems, but the problems themselveshave not beenworked out in sufficient detail to determine their scope or their resistanceto repair. ' 2.4.1. How to define what s missing? For a language learner to determine that a verb has not appeared in a structure, and that this absenceis statistically meaningful, the nature of the expected structure must be defined. As Pinker ( 1989) has pointed out , the structures cannot be individual sentencetokens, becausethere are an infinite number of such structures, and the odds that one of them would be encounteredin the corpus of speechheard by the learner is vanishingly small. ' Thus, the items that enter into the learner s statistical tabulations must be . Hence reference to the statistical more abstract than individual sentences structure of the environment will not be sufficient to characterize learning since the nature of the environment is partly defined by how the learner categorizes items within it . Furthermore, these categories may in fact be intrinsically linguistic in nature. Hence we are back to a basic problem in language learning : What notions about the nature of language do children

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bring to the task at hand? Referenceto statistical regularitieshas not eliminated this problem at all. We believe this characterization of the learning task is correct, but note that it is not specificto languagelearning. The useof statistical regularities by animals also depends on abstracting away from individual tokens. Furthermore , the categoriesinvolved in this abstraction processmay depend on the learning domain in question. For example, suppose a rat learns that a tone signals the absenceof shock. Each instance of a tone is a unique event, and yet the animal must abstract away from this uniquenessto similarities across the various tokens. What counts as similar may depend on the nature of the auditory system just as what counts as similar in language learning may depend on the nature of a species-specificlinguistic system. As we emphasized at the beginning of this paper, the use of some general purpose abilities (e.g., memory) in a particular task (e.g., parsing) does not preclude the important role of domain-specific factors. A complete account of the task will require a specification of the general and the specific, along with how they interact. 2.4.2. Outcomesimilarity despiteinput variability Given that languagelearning will depend in part on the statistical structure of the input , why is the outcome of the learning so robust in the sensethat all normal children attain the same basic level of competencedespite (probably) wide ' variations in what they have heard? One answer could focus on the domain-specific languagefaculty , which makescertain assumptionsabout the nature of the language (in statistical terms, the population) from which the sample was drawn (e.g., all of the sentencesin the language are either right branching or left-branching) . We would also suggesta statistical answer as an accompaniment. In particular , the learning is robust becauseof the robust nature of statistical sampling. One of the fundamental theoremsof statistics is that as the size of a sample increases, it reflects the actual nature of the population from which it was drawn with greater accuracy. Hence, one can make reliable conclusions about the population (which is too large to be examined in its entirety) from a relatively small sample. Although no two samples from , such a population will be alike, they demonstrably will 3 convergeon the sameconclusionsgiven a sufficiently large sample size. Note 3 Here is an easy way to dernonstrate this statistical principle : Instruct your cornputer to generate sarnples of randorn nurnbers between 0 and 100. Start off with two sarnples. each containing 5 cases. The rneans of these sarnples will probably differ greatly. Now continue generating sarnple pairs. but increasethe nurnber of casesin each pair . As the nurnber of cases

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117

that such an account would predict that the greatest variability in linguistic judgments should occur for relatively rare constructions, where the idiosyncrasies of the sample will have a much greater impact on learning. 2.4.3. Going beyondidiosyncrasies Instead of relying on some general learning mechanism, such as one that involves feedback regarding ungrammatical sentences , children might be able to exploit regularities about the sentenceframes that verbs could take (Pinker 1989). For example, the absenceof ' donate' from double-object datives is not an isolated fact. Rather, polysyllabic English verbs and verbs with certain stresspatterns are, in general, barred from double-object dative structures. If children could learn such regularities, they could then generalizethem to new instances. In fact, Gropen et al. ( 1989) have found that children learning English were re.luctant to generalize polysyllabic nonsense verbs from a propositional dative to a double-object dative, though they were more willing to do so for monosyllabic nonsenseverbs. This effect of syllable number did not extend to other syntactic frames, suggestingthat the children had learned about the blasesconcerning the English dative. Although Pinker ( 1989) casts the general learning and regularities approaches as conflicting alternatives, we see them as quite similar. Englishspeakingchildren may in fact detect regularities in the structure of English by being sensitive to the systematic absenceof certain verbs from double-object datives. They would , of course, have to recognize dative structures despite variations in their lexical content, and they would have to recognize that certain phonological properties of verbs are correlated with the dative structures . As noted above, some of these classification abilities may derive from characteristicsof the child ' s native linguistic capacity. However, granted that theseclassification abilities exist, the results found by Gropen et al. ( 1989) are quite consistent with the claim that children are sensitive to statistical patterns in their linguistic environment. The children in the Gropen et al. , rather than discrete. experiments were also probabilistic in their responses That is, although they were biased against generalizing polysyllabic words to double-object datives, they nonethelessdid so. This pattern follows from the fact that the English restriction is also probabilistic in nature (e.g., ' offer' can appear in the double-object dative) . Given a probabilistic input , a probabilistic output is expected. This leads to the next point . , convergingon a valueof 50. Yet getslarger, the meansof the sampleswill moveclosertogether the sampleswill obviouslydiffer in their exactsequence of numbers .

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2.4.4. Probabilistic responsesinherent to the useof statistical patterns Two items might both be members of a population , but the use of finite samplesto infer characteristicsof the population could lead to some differences in how they are treated. Confidencein the membershipof item I might be lessthan confidencein the membership of item 2. When applied to language, this aspectof statistics means that two sentencescould, in fact, be grammatical in the language, but speakersmight differ slightly in their opinions. One of the sentencesmight be judged more strange than the other, or rated as grammatical more slowly than the other. In fact, when subjectsare asked to rate sentenceson scalesof grammaticality, they find the task fairly easy, they do rate items as somewherebetween grammatical and ungrammatical, and they agree among themselveson these ratings (e.g., Fisher et al. 1991) . 2.4.5. Contradictory evidencefrom the domain of human decisionmaking Over the past two decades, voluminous evidence has been gathered that human beings are actually very poor in statistical reasoning (seeNisbett and Ross, 1980, for a summary) . For example, they often ignore base rate information , have incorrect ideas about randomness, and do not realize that large samples provide better estimates of a population than small samples. Given thesewell-documented problems, how could human beings use statistical information as an effective learning tool ? We will offer two parries to this objection. First , lack of explicit understanding of statistical principles does not entail lack of some type of richer implicit knowledge. This knowledge might be relatively inaccessibleto conscious access , and yet still be useful in perception and action. For instance, human being have a very poor understanding of physics when problems are presentedin a verbal format (e.g., McCloskey 1983) . Thus, they often believe that certain impossible descriptions of moving objects are, in fact, accurate statements. However, when presentedwith computer-generateddynamic displays , they now correctly recognize the natural and unnatural motions (Shannon 1976) . Of course, we normally base our actions on visual perception of actual motion rather than verbal descriptions of it . Second, the manner in w~ich the statistical information is presented in the decisionmaking experiments differs markedly from the way that information is normally experienced. In the former , information about base rate (i.e., frequency of occurrence) is given as an explicit sum. Thus, subjectsmight be told that a city contains 100cabs, with 80 being blue and 20 green. However, we rarely receive explicit information about frequency, and animals literally never receivesummary data tables. Instead, most of the frequency knowledge

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that we and other animals have is probably obtained through numerous encounters with individual objects or events. Hence, we cannot use experiments in decision making as a strong basis for conclusions about human sensitivity to statistical patterns, especially since studies have found differences in the way people treat the samedata when presentedin summary format or as a seriesof events(e.g., Wassermanand Shaklee 1984) . Rather, we must examine direct investigations of human sensitivity to frequency information , and the potential roles of such knowledge in solving problems in language and other domains. We turn to theseissuesin the following sections.

3. The useof multipleandprobabilisticinformationsourcesby humanbeings As the precedingdiscussionillustrates, non-human animals have well-documented ' abilities to detect the statistical texture of their environment. Such statistical sensitivity has been documented in numerous species and in a variety of settings, ranging from highly constrained laboratory environments to open field situations. The evolution of these abilities along with their speciesand domain generality should not be surprising given their obvious use in a variety of tasks such as foraging. In this section, we will turn to human beings and summarize some of the evidencethat we also are sensitive to and rely extensivelyon probabilistic information from multiple sourcesin order to solve a variety of problems. This section will focus primarily on nonlinguistic domains, with the next section turning to implications for language processing. The topics that we will discuss here should not be considered exHaustive, but instead viewed as a sampling from the available evidence. 3.1. General sensitivity to frequency information

In order to effectively use probabilistic infonnation , human beings must, of course, be sensitive to the relative frequencies of various events. Numerous experimentsacrossthe past four decadeshave establishedthat human beings possess this prerequisite ability (though controversy continues over the mechanismsthat might underlie it , cf. Hintzman 1988, Jonides and Jones 1992) . Furthennore, this frequency sensitivity seemsto be general in nature, as it extends across numerous domains (see Hasher and Zacks, 1984, for a more detailed review) . For instance, studies have shown that people are quite sensitive to the relative frequencies of right and left -handers (Coren and Porac 1977), encounters with different people (Saege~ et al. 1973), the

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lethality of different events (Lichenstein et al. 1978), and even fast-food restaurant chains (Shedier et al. 1985) . This frequency sensitivity appears not only across domains, but also across tasks. Whereas some studies explicitly ask subjects to rate items in terms of frequency, others use more indirect probes. For instance, in numerous experiments, Zajonc ( 1968) has found that the more frequently something is experienced, the more it is liked (even though the subjectshave no control over theseexperiences ) . Hence frequency sensitivity can be revealedby subjective evaluations. As with fast-food restaurants, numerous experiments have shown that human beings are sensitive to the relative frequencies of many linguistic events, such as words (Shapiro 1969), syllables (Rubin 1974), and letters (Attneave 1953). 4 Indeed, this sensitivity to frequency is quite strong. For example, Attneave asked subjectsto estimate the frequency of English letters per thousand tokens. He found that fully three-quarters of the variance in the ' subjects responsescould be accounted for by the actual frequencies of the letters in English text. Using different techniquesand word frequency as the object of study, Shapiro ( 1969) found that over 85% of the variance in judgments of word frequency could be accounted for by measuresof actual 5 frequency. In fact, this frequency sensitivity might be even stronger than these experimentsindicate, given that our measuresof actual frequency are subject to typical errors of sampling. These errors will be particularly apparent for low frequency items. For example, Gernsbacher ( 1984) points out that the words ' boxer' , ' icing' , and 'joker ' have the samefrequencies(namely, one per million ) as ' Loire ' , ' gnome' , and ' assay' in the two most widely used frequency norms for English. However, there is clearly no doubt that the former words are ' really' more commonly encountered, and that a sufficiently large sample of English would confirm these intuitions . In fact, the validity of the 4 Thesevariablesare, of course , correlatedin that relativelycommonsyllablestend to contain . However . , the variablescan be statisticallyseparated relativelyfrequentlettersand phonemes Thus, Rubin ( 1974 aresensitiveto syllablefrequencyindependently ) foundthat Englishspeakers of phonemefrequency . 5 Thestrengthof thesecorrelationscan, of course , beinfluencedby the rangeof materialsused. ' and ' zinc' were If only the words' the' , ' house , judged, the correlationbetweenratedand actual frequencywould obviously(and trivially) be perfect. SinceAttneaveusedall the lettersof the , the resultsfrom his experimenton letter frequencycannot be criticizedas Englishalphabet artifactsarisingfrom the typesof lettersselected . Shapiro( 1969 ) used60 words for his adult . Using455 , and theserangedfrom very high throughintermediateto low frequencies subjects wordsin a lexicaldecisiontask, Gemsbacher found that ratedfamiliarity accountedfor ( 1984 ) . morethan 71% of the variancein reactiontime.

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intuitions in this casesuggeststhat human ratings of frequency might in fact be more useful in experiments than listings in word frequency norms, and Gemsbacher ( 1984) found that subjects agreed quite well on their ratings of word familiarity , and that these ratings were better predictors of reaction times in a lexical decision task than supposedmeasuresof ' actual' frequency. Given that human beings are sensitive to frequency, sampling considerations might lead one to expect that their frequency judgments would be more accurate than current frequency norms. After all , the Francis and Kucera frequency norms are based on an analysis of one million word tokens, which is a relatively small sample. Given conservative assumptions (speech/reading rates of ISO words per minute along with an eight-hour sample per day), a typical person will be exposedto a million -word sample in about two weeks. In sum, human beings are sensitiveto frequency information in a variety of domains. This domain-independencesuggeststhat this sensitivity is a general ability and hence might be exploited in a variety of domain-specific tasks. Nonetheless, we must emphasizethat human beings are far from infallible in their frequency judgments. For example, .they tend to overestimate the frequency of rare events and underestimate the frequency of common events (seeBaron, 1988, for a summary) . In addition , frequency estimatesare based at least in part on factors other than frequency. For instance, one category is often consideredto be larger than another if instancesof the former class are more easily retrieved from memory. Now , these retrieval effects might be correlated with actual frequency, and so be reasonably accurate. However, they also might reflect aspects of memory organization itself. Thus, people ' ' generally and falsely believe that more English words begin with r than have ' r ' as the third letter. Theseintuitions probably reflect the fact that the mental lexicon is organized by first rather than third letter and/ or phoneme, and henceexemplars of the former class are more easily retrieved from memory. however, despite these inconsistencies, the evidence as a whole supports the view that human beings, like other animals, can learn probabilistic patterns in their environment. We will now turn to a sample of some areas where multiple , probabilistic information sourcesare available and might be used to solve particular problems in perception and cognition . 3.2. Depth perception One of the fundamental questions in the history of visual perception concerns how we perceive a three-dimensional world based on a two- dimensional image. Centuries of research on this question have focused on two

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issues, one optical and the other psychological. First , what types of optical patterns exist in the two-dimensional image that are correlated with the threedimensional world that reflected the image to the eye? Second, which of these information sourcesare actually used in visual perception, and how are they weighed? The second question becomes particularly important given that numerous potential cues to depth exist, such as those listed in table I .

TableI Somevariablesthat arecorrelatedwith distance Variable

Description

Binocular disparity Motion parallax Accommodation Relative size Height in picture plane Texture gradients Occlusion

Differencesin the image of an objected projected to the two eyes The relative velocity of imagesacross the retina Changesin the shape of the lens The size of an image on the retina The location of an image along the vertical axis The e , shape, and densityof textureelementslike pebbles , tiles on a floor An object blocking the view of a more distant object

Of course, these cues vary in their range and predictive power. Thus accommodation is not effective beyond 10 feet, and height in the projection ' place can easily be violated (e.g., a person s head will be higher in the projection place than the feet, yet is not further away from an observer) . Nonetheless, many cuesare simultaneouslyavailable, and hencean important issueconcernshow the various cuesare weighedand whether an available cue might even be used. The situation could be complicated further becausethe weights given to a set of cuesmight vary with context. Consider, for example, the caseof textural cuesto depth. Many surfacesconsist of textured elements, such as pebbles along a path or tiles in a room , that have roughly the same size and shapeand are distributed randomly . However, becausethe elements can systematically vary in their distance from an observer, their projected imageswill vary also. As distance from the observer increases, the images of the texture elements will decreasein size, compress in shape, and become more densely packed. Investigations of these variables have found that human observers(a) are sensitive to all three dimensions, but (b) respond to some dimensions more strongly than others, and (c) change their weightings with context (Cutting and Millard 1984). In particular , for flat horizontal surfaces, the size gradient had the greatest effect in creating impressions of depth, followed by the density and shape gradients. However, for curved surfaces, the shapegradient dominated over the other variables.

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Given that cues vary in their effectiveness , one might consider the extreme whether some cues case, and inquire , though present, might receivea weight of zero, and hence be totally ignored. Such total neglect might appear most clearly when another more powerful cue is present. In such a situation , visual processing might engage in what Bruno and Cutting ( 1988: 162) call cue ' selection' in which ' observers ... use the , single most effective available ' . For instance a static information source and the others , , pictorial [ ] disregard cue to depth, like height in the image plane, might become ignored when motion parallax is present, given that the former is lessconsistently predictive of distance. However, using a variety of experimental methods, Bruno and Cutting examined the impact of motion parallax, height in the image plane, occlusion, and relative size on distancejudgments, and found that all of these variables contributed significantly to those judgments. Such results indicate that human beings use a variety of cuesin three-dimensional perception, even cuesthat are not completely reliable.

3.3. Categorization When subjectsare asked to judge the truth fulness of category membership statementslike ' An x is a V ' , where Y is a category term and x is a possible member, their time to respond consistently varies depending on x (cf. Smith and Medin , 1981, for summary) . For example, subjects take longer to ' ' ' ' ' ' respond true to An ostrich is a bird than to A robin is a bird . These reaction time patterns can be predicted by examining the extent to which an es features typically associatedwith the category in question instance possess e. . Rosch and Mervis 1975). In the case of birds, these might be flight ( g, capacity, relatively small size, song, etc. This interpretation of the reaction time phenomenaindicates that numerous information sourcesare used in the processof categorization. Indeed, some have claimed that the reaction time (and other) data indicate that membership in categories is not discrete, but rather continuous, or that human beings believe that category membership is usually fuzzy. However, subsequentresearchhas cast serious doubt on these conclusions. For example, the status of an integer as even or odd is clearly discrete. A simple, straightforward definition sufficesto unambiguously classify any integer as even or odd. If the classification decision data reflect the fact that human beings typically lack knowledge of category definitions and/ or believe that category membershipis generally fuzzy, then the decision data should look rather different if subjects have to classify integers as even or odd. If subjects know the mathematical definition and explicitly admit that

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category membership is completely and unambiguously determined by that definition , then all integers should be classified as even or odd with equal speed, so long as confounding variables like word frequency are control led. However, Arm strong et al. ( 1983) found that some numbers are in fact classified as even or odd faster than other numbers. Indeed, for a range of categoriesthat had clear, agreed-upon criteria for membership, Arm strong et al. found that some members were consistently classified faster than others. Given these results, Arm strong et al. argue that , whatever the reaction time data indicate, they do not imply that items are members of categories to varying degrees, or that people believe in graded category membership. We agree completely with the rationale for the Arm strong et al. experiments and their conclusions. However, we nonetheless believe that the reaction time data reflect certain aspectsof the processof categorization. In particular , even when a criterion exists that is necessaryand sufficient for category membership, people cannot help but weigh other factors that are correlated with membership, though in the final analysis such features are irrelevant. For instance, prime numbers are almost always odd (2 being the only counterexample). This feature is, however, neither necessarynor sufficient for being classified as odd. Still , the feature might be weighed in classification, with prime numbers being classified as odd faster than nonprime . Consideration of such other factors might be beneficial by speedingup decision times while keeping error rates low. This advantage might also be illustrated in the following phenomenon. 3.4. The word superiority effect

' ' Suppose subjects view a clearly printed letter k either by itself or in a ' word , and they must identify whether a ' k or some other letter was presented. Numerous experiments using variations on this task have repeatedly found that subjectsidentify the target letter more accurately if it appears in a word than if it appears by itself (e.g., Reicher 1969, Johnston 1978) . ' ' Thus, ' k ' would be identified more accurately in the context of work than alone (or in a string of letters that do not form a word ) . Why is the word context advantageouseven though the letter in isolation is clearly printed ? One possibility concerns the high speedswith which skilled readers process orthographic material. Given that the context in which a letter appears is perceptual partly predictive of its identity , observers could bypass complete ' encoding of a letter, and use partial information about a letter s appearance plus partial information about the identity of surrounding letters to speed

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overall processing while minimizing error rates. Thus, observers could circumvent the usual tradeoff between speed and accuracy by using multiple sources of information about letter identity . Of course, this additional information is probabilistic in nature, given that words other than ' work ' ' ' ' ' ' ' begin with wor , such as word and worm . Nonetheless, human beings are apparently sensitive to this probabilistic information , and use it to increase processingspeed.

4. Probabilisticinformationandlanguage process ina In this section, we will review some evidence that multiple , probabilistic information sourcesare used to solve various tasks in language processing. We will focus on phoneme perception, word boundary identification , and the assignmentof words to grammatical categories. Other potential examplesalso exist, such as word identification in sentencecontexts and assignmentsof words to agent and patient roles. SeeMassaro ( 1991) for discussion of these and other cases, along with mathematical models of some of these phenomena . 4.1. Speech perception

As in the case of visual depth perception, numerous acoustic cues for phonemeidentification exist. Indeed, Lisker ( 1978) lists fully sixteen variables that could be used by listeners to determine whether a / b/ or /p/ is present in ' ' . Furthermore numerous rud , experimentshave shown that listenersweigh in variables multiple speechperception. Many of these experiments exploit the possibility of trading relationships between different acoustic cues for phonemecategories. In particular , supposethat the values along two acoustic dimensions could be used to distinguish between two phonemesA and B. If these two dimensions are in fact weighed by the listener, then shifts in the value of one dimension toward the B category should be offset by compensatory changestoward the A category in the value of the other dim ~nsion. This paradigm has been used to document the existence of a variety of trading relationships. For example, both voice onset time ( VOT) and r~lative aspiration are potential cues for distinguishing voiced from voicelessstop consonants . With amplitude of aspiration held constant, a particular VOT value can be identified as the approximate boundary betweena voicelessand voiced stop consonant. However, if the aspiration amplitude is then raised, thus

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increasing the evidence for an unvoiced consonant, the VaT boundary betweenthe two phoneme classeswill shift toward shorter VaTs . Hence, an ' ' aspiration value that indicates unvoiced can be offset by a suitable VaT ' ' indicating voiced . Such results indicate that both VaT and aspiration are weighed in distinguishing voiced from voiceless consonants (Repp 1979) . Similar trading relations have been found for formant transition duration and the duration of the following vowel, which are used to distinguish jbj from jwj (Miller and Liberman 1979), silence duration and Fl onset frequency, ' which are involved in the distinction between ' say' and ' stay (Best et al. 1981), and many other contrasts (seeRepp, 1982, for summary) . Furthermore experimentsindicate that infants as well as adults weigh multiple variables in speechcategorization (Miller and Elmas 1983) . The huge mass of this speech ' perception evidence leads to the conclusion that listeners will make use of ' any cue for a given phonetic distinction (Repp and Liberman 1987: 98) . Even further , listeners will combine multiple cues to identify phonetic segments. The search for multiple information sourcesin speechperception has been driven in large part by the failure to find invariant relationships between acoustic structure and phoneme categorization. If such invariants did exist, then they would presumably be sufficient in themselvesto distinguish between phonemes. Other, probabilistic cues, though present, might then be considered superfluous. One possible invariant that has been identified and explored over the past decadeinvolves the spectral shapeof a stop consonant release burst. Blumstein and Stevens ( 1979) have argued that place of articulation distinctions among stop consonants are invariantly signaled by this variable. For example, alveolar stops exhibit a gradual rise in amplitude as frequency increases, whereas labial stops show a falling or flat amplitude pattern. Experiments have, in fact, shown that listeners are sensitive to this information (Blumstein and Stevens1980) . However, even if this information is invariant , its presenceapparently does not eliminate the effects of other, probabilistic cues for stop consonant identity . Indeed, when the invariant and probabilistic information conflict , the latter dominates (Walley and Carrell 1983). These results are analogous to the literature in visual depth perception, in which probabilistic cues to depth are exploited even if more powerful cues are also present. They also emphasize the danger of assuming that the measuredstrength of a cue will map directly onto cue weights in perception. 4.2. Identification of word boundaries Identifying

word boundaries in continuous

speech is one of the major

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problems in speechperception, languageacquisition, and the development of speechrecognition devices. In contrast to our intuitions regarding our native language, invariant cuesto word segmentationdo not appear to exist. Hence, our impressionsof an unfamiliar languagemight better capture the true state of affairs in the sound stream: Words seemto be tightly knit together, with no obvious seamsthat can be used to teasethem apart . In fact, errors in word ' segmentationoccur in learning and listening to one s native language, testifying to the difficulties involved in this task. Segmentationproblems are wellattested in the acquisition literature (e.g., Gleitman et al. 1988), and uncertainties ' ' ' over whether ' a napron or an apron was spoken may have caused the former to have lost its initial / n/ over the course of English history . Despite its clear difficulties, listeners nonethelessbecome quite skilled at word segmentation, and numerous researchershave tried to identify the types of cues listeners can and do use to solve this problem. These investigations have uncovered cues that exist at various levels of language structure, from constraints on phoneme sequencesto patterns in the prosody. None of these cuescan guarantee successin word segmentaition, either alone or in concert, but their joint effectsmay conspire to make word segmentationby and large successful. 4.2.1. Phonemesequences Languagesoften have restrictions on phonemesand/ or phoneme sequences at syllable, morpheme, and word boundaries. Some of these restrictions are strong constraints, such as the impossibility of obstruent + nasal sequences within English syllables. However, large-scale corpora analyses might also reveal probabilistic relationships between the distributions of phonemesand various boundary types. Speakersdo appear to have some knowledge of such probabilistic relations. Thus, Cutler et al. ( 1987) have shown that English speakers have learned that English consonant vowel sequencesare more likely to follow a CVCV than a CVCC pattern . Experiments on human sensitivity to frequency information have found that people are not only sensitiveto the frequenciesof individual letters (Attneave 1953) and syllables (Rubin 1974), but also to letter combinations (Underwood 1983) . Given that letter combinations will be correlated with phoneme combinations, such data indicate that speakers also have knowledge of the relative frequencies of . However, experiments need to be performed to see if phoneme sequences not just to the overall frequency of phoneme sequences sensitive , are speakers but also to significant interactions between those frequencies and syllable, morpheme, and word boundaries.

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4.2.2. Syllable cues Individual syllables may vary in the likelihood with which they signal word boundaries. In a recent analysis, we examined four common English syllables - / 9~/, / b /, / m/, and / ~/ - and estimated their probability of occurring before a word boundary . For example, / ~/ occurs before a word boundary in ' a . maze' and ' Louisiana cooking' , but not in ' amaze' or ' astounding' . The analysesrevealed that / 9~/ and / b / almost always appear just prior to word boundary, followed by / ~/ and then / m/ . As a result, it is far easier to find ' ' ' ' ' ' ' ' English words like increase, invade , applause, and approach than words ' ' ' ' like today and topeka . We recently conducted an experiment to test whether English speakershave knowledge of theserelationships. This experiment used a one-word / two -word judgment task. In this procedure, subjects hear a sequenceof two syllables and must judge as rapidly as possible whether the sequencecorrespondswith one word or two. The critical items consisted of quadruplets such as ' the mind ' , ' a mind ' , ' to mind ' , and ' in mind ' . In thesecases, a monosyllabic open class word is precededby one of four monosyllabic closed class words, with the closedclasswords varying in the likelihood with which they signal a word boundary. If English speakers have learned these probabilities and exploit them in word segmentation, then we would expect faster ' two -word ' judgments for those syllablesthat most reliably correspond with word boundaries. In addition , listeners should make fewer errors with these items. The filler items consisted of disyllabic words such as ' typhoon ' . All of the disyllabic words had stresson the secondsyllable, and so matched the stresspatterns of the two-word cases. This control prevented the subjects from using stress pattern as a guide to the correct answer. The results from this experiment are presented in table 2. Statistical analysesrevealedthat subjectswere significantly faster and made fewer errors for the / 9~/ and / b / conditions than for the / ~/ and then / m/ conditions. In Table2 Mean reactiontimes(in msec ) and error rates(pereight items) to identify a disyllabicpattern ' ' (e.g., the mind) as two wordsdependingon the initial word in the pattern

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addition , I ~I was significantly easierthan Iml on both the speedand accuracy measures. The 19~1 and Ibl conditions were not significantly different. We are currently planning a secondexperiment involving Ib / , I ~/, and Im/ . The same one-word/ two -word task will be used, but in this case, the target syllableswill ' ' ' ' ' ' actually be part of a word as in tomorrow , abandon and infection . The ' ' correct answer here is one word , but the predictions are exactly the opposite ' of those made for the samesyllablesin the ' two word context. Now , listeners should be fastest and make the fewest errors with Iml items and be slowest and make the most errors with the Ib / items. 4.2.3. ~rosodic structure Cutler and her colleagueshave recently argued that the distinction between strong and weak syllables, which is a major characteristic of English prosody, can provide powerful cues to word segmentation. Whereas strong syllables have a full vowel, weak syllables have a reduced vowel, which is typically though not exclusively realized as a schwa. In extensive analysesof English speechcorpora, Cutler and Carter ( 1987) found that over 70% of strong syllables coincided with a word boundary. Our own unpublished analysis of parental speechto children between 12 and 25 months of age is even more strongly marked. Across the 14 mothers in our sample, strong syllables corresponded with word boundaries 95% of the time, with 93% being the LOWEST value in the corpus. 6 Hence, a productive word segmentation strategy for English would divide an utterance at the beginning of each strong syllable, and submit the resulting units to a lexical search. In general, these units will match words in the lexicon, and the failures can be subjected to some type of re-analysis. Current evidence indicates that listeners do, in fact, use some version of this strategy. First , Cutler and Butterfield ( 1992) predicted that when listeners make word segmentationerrors, they should remove weak syllables from the beginnings of words and attach them to the ends of words. Analyses of 6 Of course, the mothers are not deliberately making their speech more predictive of word boundaries so as to assist their children in acquiring English. Rather, parental speechcontains a strikingly high percentageof words that refer to concrete objects and easily perceivableevents, for the good reason that children are more interested in these entities rather than more abstract themes like religion or politics . Given that the vocabulary of everyday objects contains a high proportion of monosyllabic words and is drawn from a core Germanic lexicon that is character ized by polysyllabic words beginning with strong syllables, a greater correspondencebetween strong syllables and word boundaries will appear in parental speech than in speech between adults.

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naturally -occurring and experimentally-induced segmentationerrors supported thesehypotheses. For example, a listener misheard ' bought a Mercedes' as ' Mortimer Sadies' , which involved detaching the weak initial syllable of ' Mercedes' and ' ' appending it along with the weak a to the strong first syllable. (Of course, some phoneme misperceptionsoccurred as well.) Second, Cutler and Norris ( 1988) found that listeners took longer to identify the real word 'mint ' in ' mintayf ' than in ' mintef' . Cutler and Norris argued that since ' mintayf ' contains two strong syllables, listeners would initially segmentthe syllablesinto separateword-units after the In/ . As a result, the listenerswould have to overrule the initial word boundary and reunite the It I with the ' preceding syllable. In mintef' , on the other hand, no word boundary would be inserted between the Inl and It I since the final syllable is weak. Thus, the subjectswould not have to rectify incorrect word boundaries in this case, and their reaction time would be faster. Finally , although Cutler and Carter' s corpus analysis indicated that a strong syllable generally marked a word boundary, numerous segmentation errors would still be made with a simple heuristic that always and only placed word boundaries before strong syllables . However, Cutler and Carter point out that most of the errors in this case would involve closed-class items as these are the principal words that violate the strong syllable heuristic. Indeed, they systematically violate the heuristic becauseword boundaries generally appear before weak syllables of closed class words but strong syllables of open class words. If English speakershave learned this pattern, and supplementedtheir word segmentation strategies with it , they could further reduce the chances of a missegment . In fact, segmentationerrors themselvesprovide some evidence that English speakershave learned these prosodic patterns. Although Cutler and Butter worth ( 1982) found that segmentationerrors tended to place word boundaries before strong syllables, some did in fact occur before weak syllables. However, most of these casesposited a closed-classword immediately after the boundary.

4.3. Parsing In determining the grammatical structure of . a sentence, listeners and readers are often faced with local ambiguities. For example, in a sentence ' ' beginning with The judge knew the law ... , the final noun phrase could be ' ' the direct object of knew or the subject of a complement clause. In attempting to understand how such ambiguities are dealt with , two major questions have been intensely investigated: What information is brought to

M .H . Kelly , S. Martin I Domain-general abilities

bear on the ambiguity , and when is that information available? Over the past two decades, the dominant answershave claimed that only a restricted range of information contributes to initial parsing decisions, with other classesof information only coming into play later to rectify errors in the first parse (e.g., Frazier and Fodor 1978, Frazier and Rayner 1982, Ferreira and Clifton 1986, Ferreira and Henderson 1990) . In particular , preferencesfor certain phrase structure geometries are used to guide initial parsing, such as a preference to create the simplest phrase structure tree consistent with the preceding input . These preferences are reputedly blind to other types of information , such as the identity of the verb in the sentence. The impenetrability of certain information classesto parsing mechanisms createsvery interesting predictions. Consider, for example, the sentences' The student forgot the solution was in the back of the book ' and ' The student ' ' , the hoped the solution was in the back of the book . In both sentences ' ' solution is the subject of a complement clause. However, a complement clauseinterpretation would create a more complex phrase structure tree than an interpretation that initially categorized' the solution ' as the direct object of the respectiveverbs ' forgot ' and ' hoped' . Hence, upon reaching ' the solution ' , a reader might opt initially for the simpler direct object parse, which would have to be rejectedwhen later disconfirming information is encountered. Still , one might entertain the possibility that the identity of the verbs themselves could affect theseinitial parsing blases. Although ' forgot ' can be followed by an NP object or an object clause, ' hoped' cannot appear with the former structure. If such facts about verb argument types can influence the earliest stages of parsing, then one would predict that readers would not posit a direct object interpretation for ' hoped' , and so would not need to reject such a hypothesis when subsequentportions of the sentenceare read. One would therefore predict that reading times for the disambiguating areas of the sentencewith ' hoped' would be faster than those for the same areas of the sentence with ' forgot ' . This prediction and analogous ones using other dependentmeasuresand experimental procedureswere supported in a set of studies by Trueswell et al. (in press b) . The results could not be attributed to ' ' ' ' generally faster processingof forgot than hoped becausethe reading time differencesbetween the verbs were significantly reduced in control sentences ' ' containing the complementizer that , which made the sentencesunambiguous . Although some studies have been reported that did not find effects of verb subcategorization preferenceson parsing (e.g., Ferreira and Henderson 1990), Trueswell et al. argue that thesestudies have a number of methodological flaws. For instance, the verbs used by Ferreira and Henderson ( 1990)

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did not differ very much in their preferencefor noun phrase versus sentential objects. Consequently, their methods were not sensitive enough to detect differences. In sum, then, the experiments conducted by Trueswell et al. (in press b) indicate that subcategorization information about a verb has immediate effects on parsing (see also Shapiro et al. 1993), contrary to models that severely restrict the class of information available to parsing mechanisms. Indeed, Trueswell et al. argue that a wide range of information sources contribute to parsing decisions. As one final illustration , Trueswell et al. (in press a) have recently provided evidence that semantic properties of the sentencesubject can influence parsing. They contrasted sentenceslike ' The defendant examined by the lawyer turned out to be unreliable' with ' The evidenceexamined by the lawyer turned out to be unreliable' . Parsing models that rely solely on syntactic preferenceswould claim that readerswould have ' difficulty with these sentencesbecausethey would initially treat defendant/ ' evidenceexamined to be the subject and verb of the main clause. Although such syntactic preferencesmight exist, Trueswell et al. explore the possibility that they could be modified by the relative prototypicality of the preceding nouns as the subject for the verb. Although ' defendant' is a reasonable ' ' ' ' subject of the verb examined , evidence is not , and Trueswell et al. provide evidence that readers weigh such information in their initial parsing processes. Thus, like visual depth perception, parsing appears to proceed by considering multiple sourcesof information , which may range from general syntactic preferencesto properties of the specific lexical items composing a sentence. 4.4. Grammatical category assignments

One problem that listeners must solve during language comprehension is the assignmentof words to the correct grammatical classes , such as noun and verb. These assignments must be made rapidly given that conversational speechproceedsat about 150 words per minute (Maclay and Osgood 1959). What types of information might listeners exploit in order to make these categorizations? Both semantic and syntactic factors are certainly available. Semantically, nouns tend to denote concrete objects whereas verbs tend to denote actions. These patterns are not invariant , but children do show sensitivity to them in experiments (e.g., Brown 1957) . Syntactically, words from different grammatical classesvary in their distributional requirementsin sentences . Thus, English nouns, but not verbs, can appear in the sentence

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stole the base' whereas verbs, but not nouns, can appear in the ' the base' . sentence The runner While not disputing the important role of semantic and syntactic information for grammatical class, we would like to explore a relatively neglected domain of information . In particular , a large number of phonological cuesto grammatical classexist, and experimentshave repeatedly shown that speakers are sensitiveto them. For example, nouns and verbs in English differ in stress pattern, syllable number, duration , vowel characteristics, and other phonolo' gical dimensions (see Kelly , 1992, for a review) . English speakers have revealed their sensitivity to these and other correlations in a wide range of tasks. For instance, if listeners hear disyllabic pseudowords that differ in stressand are asked to use each of these words in a sentence, they will use words with first syllable stress more often as nouns and words with second syllable stressmore often as verbs (Kelly 1988b) . Another set of experiments took advantage of the fact that English words often develop uses in " other ' ' grammatical categories. Thus, police originated in English as a noun, but ' ' subsequentlydevelopeda verb use, whereas fumble originated as a verb, but later developed a noun use. Despite the frequency with which these lexical extensionsoccur, blasesagainst certain types of extensions exist (Clark and Clark 1979). Although the cited blases tend to be based on semantic and pragmatic factors, Kelly ( 1988b) speculatedthat the phonological characteristics of nouns and verbs could influence the easewith which they develop uses in the other category. In particular , if English speakers have learned the correlation between stressand grammatical class in English, then they might ' ' use this knowledge as a measureof fit betweena current noun and possible verb use and vice versa. Thus, they might consider nouns to be better verb candidates to the extent that they have the prototypical verb stress pattern. This possibility was tested by presenting one group of subjectswith pairs of disyllabic nouns that differed in stress but were control led for other factors , ' The

7 Although thesecorrelationsare well- documented . However , their originsmay seemmysterious evaluated . , explanationsfor someof thesepatternshavebeenproposedand experimentally For example , Kelly ( 1992 ) hasarguedthat threefactorsmight be involvedin the evolutionof differ phonologicalpredictorsof grammaticalclass: ( I ) Wordsfrom differentgrammaticalclasses . (2) Thesedistributionaldifferencesmay havephonological in their distributionsin sentences in the waywordsfrom various with them, whichcreatecontextualdifferences reflexesassociated . (3) Overtime, listenersviewthesecontextualeffectsas classes are pronouncedand/or perceived . This accounthasbeenappliedto the Englishnoun-verb context-freepronunciations permissible stressdifference(Kelly I 988a, 1989 ), and might be ) and duration difference( Daviset al. 1992 of other, currentlyunknownphonologicalcorrelates usedas a heuristicto predictthe existence with grammaticalclass.

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such as word frequency (e.g., llama and gazelle) . Another group of subjects were presented with pairs of disyllabic verbs that differed in stress (e.g., grovel and beseech ) . None of the words had uses in the other category as determined by the most recently available Webster's Collegiate Dictionary . Subjects in the two groups were asked to select one noun (verb) from each pair and use it as a verb (noun) in a sentence. The choices were significantly affected by the stress patterns of the words, as nouns with second syllable stress were used as verbs more often than nouns with first syllable stress whereas verbs with first syllable stress were used as nouns more often than verbs with second syllable stress. These patterns are not simply a laboratory artifact . Analyses of the history of English also found the same patterns in actual grammatical category extensions down through the centuries (see Kelly , 1988b, for details) . Although such experiments demonstrate that English speakers possess implicit knowledge of the noun- verb stressdifference, and that such knowledge may even have affectedthe history of English, they do not entail that the initial identification of a word as a noun or verb is at all affected by stressor other phonological variables. That is, the subject might have recognizedthat ' ' ' ' gazelle is a noun just as easily as they recognized llama . Stressthen came into play only later as a metalinguistic variable, but did not affect initial categorization of the words. In order to determine whether stress actually affects grammatical category assignmentsearly in speech processing, Kelly and Martin ( 1993) recently conducted a noun- verb categorization task that we will summarize here. The task was straightforward : On each trial , the subjectsheard a word that they had to classify as a noun or a verb as quickly as possible. The words were disyllabic and differed in stress, with half of the nouns and half of the verbs having first syllable stress and the other half having second syllable stress. In addition to varying a phonological correlate to grammatical class, we also manipulated a semantic cue. Given that nouns generally denote concrete objects and verbs readily perceived actions, we selectedour words such that half of the nouns and half the verbs had the prototypical meanings of their class, whereas the other half denoted abstractions. It is conceivable that the phonological cue to grammatical classwould only influence grammatical category assignmentswhen the semantic cue is absent. Given that the semanticcue is universal whereasthe phonological cuesare languagespecific, one might expect the former to be more basic and perhaps completely eliminate effects of the phonological cue. The results indicated that both semantic and phonological factors affected the subjects' judgments. Nouns

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and verbs were classified faster if they had meanings typical of their classes. In addition , the phonological variable of stressinteracted with grammatical classsuch that nouns were classifiedfaster if they had first syllable stressbut verbs were classified faster if they had second syllable stress. Most importantly , the phonological effects were not eliminated for words that had concrete meanings. Indeed, these effects were significantly magnified by the presenceof semantic features that convergedon the samecategorization. The effect of concretenesswas likewise magnified by the presenceof appropriate phonological features. For example, concrete nouns with first or second syllable stress were classified faster than abstract nouns with either stress pattern. However, the differencebetweenthe concrete and abstract nouns was larger for items with first syllable stress. For verbs, on the other hand, the concrete/ abstract difference was larger for items with second syllable stress. Thus, listenersappear to use a conspiracy of cues to identify the grammatical category of a word . These cues can either be language-universal, like the semanticcue to grammatical class, or language-specific, like stressin English. Finally , the language-specific cues are not overwhelmed or even damped by the language-universal factors. Instead, they mutually reinforce one another.

5. Conclusions

In this paper, we have submitted arguments and evidencefor the following claims: ( I ) Multiple sources of information are available to solve problems in perception and cognition . 2 ( ) These information sources, though plentiful in number, are often probabilistic in nature. Nonetheless, if multiple probabilistic sourcesconverge on the solution to a problem, that solution is likely to be correct. Reliance on multiple cues should therefore produce greater successthan reliance on an individual cue. 3 ( ) Given ( 1) and (2), one would expect to see widespread sensitivity to probabilistic information throughout the animal kingdom . Furthermore, since many problem domains are characterizedby probabilistic solutions, sensitivity to variables such as frequency and rate of return should be a domain-general ability . This general ability could, like memory, be involved -specificproblems that have domain- dependentcharacteristics in species . The current evidence from the human and non-human animal literature strongly supports the hypothesis concerning sensitivity to pro -

M .H . Kelly , S. Martin I Domain-general abilities

babilistic information . Its domain-independence and interactions with -specific abilities need to be heshed out in much species greater detail, however. (4) Sensitivity to multiple sources of information for solving particular problems should be widespread and domain-independent. We have reviewed some areas, such as visual depth perception, where this claim appears to be correct. Language appears to be no different from other domains in this regard as numerous studies have shown that speakersare sensitive to statistical regularities in their language, even though some of these patterns are quite subtle. Extensive research remains to be performed to determine if such knowledge is actually exploited in language acquisition, comprehension, and production . In conclusion, over the past few decades, cognitive scientists have moved away from t ~e position that general principles operate across cognitive and ' perceptual domains. Instead, research and theory ranging from cognitive development (e.g., Chi 1978, Keil 1989) to animal learning (e.g., Seligman 1970) have emphasizedthat domain- dependentprinciples might constrain the ways in which human beings gather, organize, and draw inferences from different kinds of information . This approach recognizes that organisms confront many problems whose solutions require specific kinds of information that must be manipulated in highly constrained ways. As a result, the manner in which, say, migrating birds solve their navigational problems will probably not provide us much guidance in determining how children acquire the meaningsof words in their language. However, the value of the domainspecific approach should not causeus to neglect the fact that similar types of problems are in fact encounteredacross domains, and hencedomain-general solutions might have evolved to deal with them. The inherent probabilistic nature of an animal' s environment is one such invariant , and sensitivity to probablistic patterns appears to permeate perception and cognition, even in areas like language that seemto be highly constrained by domain-dependent principles.

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. Journalof . Psychological Attneave , F., 1953 probabilityasa functionof experienced frequency 46 81 86. , Experimental Psychology . . Thinkingand deciding . New York: CambridgeUniversityPress Baron, J., 1988 . Perceptualequivalence of acousticcuesin Best, C.T., B. Morrongielloand R. Robson, 1981 . Perceptionand Psychophysics 29, 191-211. perception speechand nonspeech . Acousticinvariancefor placeof articulationin speech Blumstein , S.E. and KiN. Stevens , 1979 . of stop consonants of the spectralcharacteristics production: Evidencefrom measurements - 1017 . Journalof the AcousticalSocietyof America66, 1001 . Perceptualinvarianceand onset spectrafor stop Blumstein , S.E. and KiN . Stevens , 1980 . Journalof the AcousticalSocietyof America67, consonants in differentvowelenvironments 648- 662. . Journalof Abnormaland Social . Linguisticdetenninismand part of speech Brown, R., 1957 49, 454- 462. Psychology . Minimodularityand the perceptionof layout. Journal of Bruno, N. and J.E. Cutting, 1988 : General117, 161- 170. Experimental Psychology . In: R.S. Siegier(ed.), . Knowledgestructuresand memorydevelopment Chi, M.T.H., 1978 ?, 73-96. Hinsdale Children's thinking: What develops , NJ: Erlbaum. . Whennounssurfaceasverbs. Language55, 767- 811. Clark, E.V. and H.H. Clark, 1979 : The historicalrecord. Science . Fifty centuriesof right-handedness Coren, S. and C. Porac, 1977 198, 631- 632. : Evidencefrom . Rhythmiccuesto speechsegmentation Cutler, A. and S. Butterfield, 1992 . Journalof Memoryand Language31, 218- 236. juncturemisperception . The predominance of stronginitial syllablesin the English Cutler, A. and DiM. Carter, 1987 . ComputerSpeechand Language2, 133- 142. vocabulary . for lexicalacxess . The role of strongsyllablesin segmentation Cutler, A. and DiG. Norris, 1988 : HumanPerceptionand Performance14, 113- 121. Journalof ExperimentalPsychology . A noteon the role of phonologicalexpectationin Cutler, A., D. Norris andJ.N. Williams, 1987 and - 487. . Journal of Memory Language26, 48G speechsegmentation . Threegreadientsand the perceptionof flat and curved Cutting, J.E. and R.T. Millard, 1984 : General113, 198-216. . Journalof ExperimentalPsychology surfaces betweenEnglish . The causesof durationdifferences Davis, S., J. Morris and M.H. Kelly, 1992 . nounsand verbs. Unpublishedmanuscript . Somecommonaspectsof modelsfor learningand memoryin lower animals Estes , W.K., 1985 on learningand memory, 151- 166. and man. In: L. Nilsson, T. Archer (eds.), Perspectives Hillsdale, NJ: Erlbaum. . Journalof Memory of syntacticprocessing . The independence Ferreira, F. and C. Clifton, 1986 and Language25, 348- 368. . The useof verb informationin syntacticparsing: A Ferreira, F. and JiM. Henderson , 1990 andword-by word self-pacedreading.Journalof from eyemovements comparisonof evidence : , , and Cognition16, 555- 568. Memory Learning Psychology Experimental . On the semanticcontentof subcategorization Fisher, C., H. Gleitmanand L.R. Gleitman, 1991 23, 331- 392. . CognitivePsychology frames . . Frequency Francis,W.N. andH. Kucera, 1982 analysisof Englishusage:Lexiconand grammar Boston, MA : Houghton-Mifflin. : A new parsingmodel. Cognition6, . The sausagemachine Frazier, L. and J.D. Fodor, 1978 291- 326.

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Fra2ier . Makingandcorrectingerrorsduringsentence , L. andK. Rayner : Eye , 1982 comprehension movements in theanalysis of structurallyambiguous senten ~ . CognitivePsychology 14, 17S - 210. Frazier, L. andK. Rayner, 1987 . Resolutionof syntacticcategoryambiguities : Eyemovements in . Journalof Memoryand Language26, 505- 526. parsinglexicallyantbiguoussentences Gallistel, C.R., 1990 . The organizationof learning. Cambridge . , MA : MIT Press Gernsbacher . Resolving20 years of inconsistentinteractionsbetweenlexical , M.A., 1984 . Journalof Experimental : , concreteness , andpolysemy familiarityandorthography Psychology General113, 256- 281. Gleitman, L.R., H. Gleitman, B. Landauand E. Wanner, 1988 . Wherelearningbegins: Initial for languagelearning. In: F.J. Newmeyer(ed.), Linguistics : The Cambridge representations : CambridgeUniversityPress . survey, Vol. 3, 150- 193. Cambridge Gluck, M.A. and G.H. Bower, 1988 . From conditioningto categoryleaming: An adaptive networkmodel. Journalof ExperimentalPsychology : General117, 227- 247. Gould, S.J., 1991 . Bully for brontosaurus : Reflectionsin naturalhistory. New York: Norton. . The learnabilityand Gropen, J., S. Pinker, M. Hollander, R. Goldbergand R. Wilson, 1989 acquisitionof the dativealternationin English. Language65, 203- 257. Hasher,L. and R.T. Zacks, 1984 . Automaticprocessing of fundamentalinformation: Thecaseof - 1388 . AmericanPsychologist 39, 1372 . frequencyof occurrence Hintzman, D.L., 1988 . Judgmentsof frequencyand recognitionmemoryin a multiple-trace Review95, 52S-551. memorymodel. Psychological Johnston . A testof the sophisticated . Cognition , J.C., 1978 guessingtheoryof word perception 10, 123- 153. Jonides . Direct coding of frequencyof occurrence . Journal of , J. and C.M. Jones , 1992 : Learning, Memory, and Cognition18, 36S-378. ExperimentalPsychology Just, M.A. and P.A. Carpenter . A capacitytheoryof comprehension : Individualdifferences , 1992 in workingmemory. Psychological Review99, 122- 149. Keil, F.C., 1989 . Concepts . Cambridge . , kinds, and cognitivedevelopment , MA : MIT Press . Rhythmicalternationand lexicalstressdifferences in English. Cognition30, Kelly, M.H., 1988a 107- 137. . Phonologicalblasesin grammaticalcategoryshifts. Journalof Memoryand Kelly, M.H., 1988b Language27, 343- 358. . Rhythmand languagechangein English. Journalof Memoryand Language Kelly, M.H., 1989 28, 690- 710. . Using sound to solve syntactic problems : The role of phonologyin Kelly, M.H., 1992 . Psychological Review99, 349- 364. grammaticalcategoryassignments . Phonological cuesto grammatical . Unpublished class . KeUy,M.H. andS. Martin, 1993 manuscript Kimball, J., 1973 . Sevenprinciplesof surfacestructureparsingin naturallanguage . Cognition2, 15- 47. . It ' s frogsall the waydown. Cognition15, 75-93. Levy, Y., 1983 Liberman, M., 1991 . Colloquiumpresentedto the Departmentof Psychology , Universityof . Pennsylvania Lichenstein, S., P. Slovic, B. Fischoff, M. Laymanand B. Combs, 1978 . Judgedfrequencyof lethalevents . Journalofex~ rimentalPsychology : HumanLearningand Memory4, 551- 578. Lieberman . Learning. Belmont, CA: Wadsworth . , D.A., 1990 Lisker, L., 1978 . Rapidvs. rabid: A catalogueof acousticfeaturesthat maycuethe distinction. HaskinsLaboratoriesStatusReporton SpeechResearch , SR-54, 127- 132.

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. Hesitationphenomena in spontaneous . Word , 1959 Maclay, H. andC.E. Osgood Englishspeech IS, 19- 44. . The acquisitionof morphonology . Monographsof the Societyfor , B., 1978 MacWhinney Research in Child Development 43 ( 1/2), 174. . Languageprocessingand informationintegration. In: N.H. Anderson Massaro , D.W., 1991 (ed.), Contributionsto informationintegrationtheory, Vol. I : Cognition, 259- 292. Hillsdale, NJ: Erlbaum. . Intuitive physics . ScientificAmerican24, 122- 130. , M., 1983 McCloskey . Studieson thecategorization of speechby infants. Cognition Miller, J.L. and P.D. Elmas, 1983 13, 135- 165. . Someeffectsof later- occurringinformation on the Miller, J.L. and AiM . Libennan, 1979 . Perceptionand Psychophysics 25, 457- 465. perceptionof stopconsonantand semivowel : Strategiesand shortcomingsof human . Human inference Nisbett, R.E. and L. Ross, 1980 -Hall. judgment. EnglewoodCliffs, NJ: Prentice . Expectancyand stimulusfrequency :A Pang, K., F. Merkel, H. Egethand D.S. Olton, 1992 . Perceptionand Psychophysics 51, 607- 615. comparativeanalysisin rats and humans . Lemabilityand cognition. Cambridge . Pinker, S., 1989 , MA : MIT Press . Grammaticalelementsof languagein the speechof preschoolchildren. In : , M.I., 1973 Popova C.A. Ferguson , 269- 280. NewYork: , D.I. Siobin(eds.), Studiesof child language development Holt, Rinehart, &; Winston. of stimulusmaterial. Reicher . Perceptual , G.M., 1969 recognitionasa functionof meaningfulness 81, 275-280. Journalof ExperimentalPsychology -initial stop . Relativeamplitudeof aspirationnoiseasa voicingcuefor syllable Repp, B.H., 1979 . Languageand Speech22, 173- 189. consonants evidencefor . Phonetictradingrelationsand contexteffects:New experimental Repp, B.H., 1982 ' modeof perception . Psychological Bulletin92, 81- 110. a speech . Phoneticcategoryboundariesare flexible. In: S. Hamad Repp, B.H. and AiM . Libennan, 1987 : Cambridge : The groundworkof cognition, 89- 112. Cambridge (ed.), Categoricalperception . UniversityPress . Probabilityof shockin the presenceand absenceof CS in fear conditioning Rescoria , R.A., 1968 66, 1- 5. . Journalof Comparativeand Physiological Psychology W.K. . In: . inhibition of fear R.A. 1969 Conditioned Rescoria , , Honig, N.J. Mackintosh(eds.), . issuesin associative Fundamental learning. Halifax: DalhousieUniversityPress . Pavlovianconditioning: It 's not what you think it is. AmericanPsychologist Rescoria , R.A., 1988 43, 151- 160. . A theoryof Pavlovianconditioning: Variationsin the Rescoria , R.A. and AiR. Wagner, 1972 . In : A.H. Black, W.F. Prokasy(eds.), of reinforcementand nonreinforcement effectiveness 2: research and Vol. Current aassical conditioning , theory, 64-99. New York: AppletonCenturyCrofts. : Studiesin the internal structureof Rosch, E. and C.B. Mervis, 1975. Family resemblances 7 . 573 605 . categoriesCognitivePsychology, . Perception andPsychophysics . Thesubjective estimationof syllablefrequency Rubin, D.C., 1974 16, 193- 196. : A contributionbased of inflectionin child language . On the emergence Ruke-Dravina, V., 1973 on Latvian speechdata. In : C.A. Ferguson , D.I. Siobin (eds.), Studiesof child language , 252- 267. New York: Holt, Rinehart, &; Winston. development

-generalabilities M.H. Kelly, S. Martin I Domain . Exposure , S., W. Swapand RiB. Zajonc, 1973 , context, and interpersonalattraction. Saegert Journalof personalityand SocialPsychology 25, 234- 242. . On the generalityof the laws of learning. PsychologicalReview77, , M.E.P., 1970 Seligman 406- 418. Shannon . Aristotelianism , B., 1976 , Newtonianism , and the physicsof the layman. Perception5, 241- 243. . The subjectiveestimationof relativeword frequency . Journal of Verbal Shapiro, B.J., 1969 Learningand VerbalBehavior13, 638- 643. . Preferences for a verb's complements andtheir Shapiro, L.P., H.N. Nageland B.A. Levine, 1993 usein sentence . Journalof Memoryand Language32, 96- 114. processing Shedier . Availability: Plausiblebut questionable . Paper , J.K., J. Jonidesand M. Manis 1985 at the 26thannualmeetingof the Psychonomic , Boston, MA. presented Society Smith, E.E. and D. Medin, 1981 . Categories andconcepts . Cambridge , MA : HarvardUniversity Press . Trueswell and S.M. Garnsey on parsing: , J.C., M.K. Tanenhaus , in pressa. Semanticinfluences Useof thematicrole informationin syntacticambiguityresolution . Journalof Experimental : Learning, Memory, and Cognition. Psychology Trueswell and C. Kello, in pressb. Verb-specificconstraintsin sentence , J.C., M.K. Tanenhaus -paths. Journalof Experimental : Separating effectsof lexicalpreference from garden processing : and . , , PsychologyLearning Memory Cognition . Attributesof memory. Glenview Underwood . , B.J., 1983 , IL : Scott, Foresman ' Walley, A.C. and TiD. Carrell, 19.83. Onsetspectraand formant transitionsin the adult s and child' s perceptionof placeof articulationin stopconsonants . Journalof the AcousticalSociety - 1022 of America73, 1011 . -outcomerelations: The role of E.A. Wasserman and H. Shaklee . Judging response , , 1984 outcome outcome and method of informationpresentation . , , respense contingency probability Memoryand Cognition12, 276- 286. . Attitudinal effectsof mere exposure . Journal of Personalityand Social Zajonc, R.B., 1968 2 Part 2 1 28. , PsychologyMonographSupplement 9( ),

Section 3

the Categorizing

world

-Holland 92(1994 - 167 . North Lingua ) 143

Does learning

a language

require the child to reconceptualize the world ? Susan Carey Instituteof Technology , Massachusetts , 77 Massachusetts Departmentof Brain and CognitiveScience Ave., 25-406, Cambridge . MA 02139 , USA Sortslconcepts with a count/massdistinction, provide , lexicalizedascountnounsin languages ' ' criteriafor individuationandnumericalidentity. This paperexamines Quines andPiagets claims that babiesand youngchildrenlack the logicalresources to representsortalconcepts . Evidenceis marshalledagainstthe Quine/Piagetposition, in favor of a view that evenyoung infants representat least one sortal concept , physicalobject, which providesspatiotemporal criteriafor individuationand identity. Evidenceis alsoprovidedthat babiesbelow II monthsof agemay not representmore specificsortalssuchas cup, animal, bottle, or book. Rather, they theseentitiesin a waycloselyrelatedto Quine's hypothesis . mayconceptualize

1. Intr04uctio D

Many students of language acquisition and cognitive development argue that the continuity hypothesisshould be the default, to be defeatedonly in the face of extraordinary evidence (e.g., Pinker 1984, Macnamara 1982). The continuity hypothesis is that representational format is constant throughout development; that the child has innately the logical and conceptual resources to representhis or her world as do adults. The continuity hypothesis denies ' stage changesof the sort envisioned by Piaget, denies changesin the child s ' linguistic representations such as the putative semantic category/syntactic ' category shift posited some years ago. According to the continuity hypothesis , language learning is a very complex mapping process; the child must learn which syntactic devices his/ her language employs, and which of a universal set of semantic distinctions are expressedin the syntax of his/ her language. What the child need not do, on the continuity hypothesis, is construct genuinely new representationalresources. Of course, whether the continuity hypothesis is true or not is an empirical question, and to examine it , one must entertain possibilities as to what types -3841 Science B.V. All rightsreserved 0024 /94/$07.00@ 1994- Elsevier -F SSDI0024-3841(93)EOOS8

S. Carey / Reconceptualizingthe world

of discontinuities could possibly obtain in the course of development. If evidence for discontinuities is found , several further questions are then licensed, including : ( 1) by what mechanism is the change effected (e.g., maturational , learning by some other process than currently understood parametersetting or hypothesis testing methods) . (2) What is the relation betweenthe discontinuity and languagelearning? Is somechange in representational resources required as a prerequisite to some aspect of language learning? Alternatively , does language learning playa role in causing the change? ' Here I examine an important discontinuity proposal of Quine s, versions of which are endorsed by thinkers as diverse as the British empiricists and Piaget. Quine, Piaget, and others maintain that early representationsof the world are formulated over a perceptual quality space(Quine, the empiricists) ' or sensori -motor representational system (Piaget) . On both Quine s and ' Piaget s views, the baby is not capable of formulating any representations with the properties of adult concepts such as object, dog, table. ' Quine s proposal is that the ontology that underlies language is a cultural construction . ' Our conceptual firsts are middle -sized, middle distanced objects, and our introduction to them and to everything comesmidway in the ' cultural evolution of the race (Quine 1960: 5). Before the child has mastered ' this cultural construction, the child s conceptual universeconsistsof representations of histories of sporadic encounters, a scattered portion of what goes ' on. Quine speculatesas to the representationsunderlying the toddler s usesof ' ' ' ' ' ' ' the words water , red , and Mama . His first learning of the three words is uniformly a matter of learning how much of what goes on about him counts as the mother, or as red, or as water. It is not for the child to say in the first ' ' ' case, ' Hello , Mama again , in the secondcase Hello , another red thing , and ' ' in the third case, Hello , more water . They are all on a par : Hello , more ' Mama , more red, more water (Quine 1960: 92) . The child mastersthe notion of an object, and of particular kinds of objects, in the course of getting the ' ' hang of what Quine calls divided reference, and this through the processof ' ' ' mastering quantifiers and words like same. The contextual learning of these various particles goes on simultaneously, we may suppose, so that they are gradually adjusted to one another and a coherent pattern of usageis evolved ' matching that of one s elders. This is a major step in acquiring the conceptual schemethat we all know so well. For it is on achieving this step, and only ' then, that there can be any general talk of objects as such (Quine 1969: 910) . And in another place he finishes the same idea with a bootstrapping metaphor, underlining the degreeof conceptual changehe thinks is occurring :

S. Carey/ Reconceplua Ilzing lhe world

' The child scrambles up an intellectual chimney, supporting himself against each side by pressureagainst the others' (Quine 1960: 93) . Quine also states that once the child has masteredthe notion of an object, and got the trick of divided reference, he goes back and reanalyzes' Mama ' , so that it is now the name of a unique enduring person. ' Quine s view can be schematizedas follows. Imagine a portion of bottle experience that we adults would conceptualize as a single bottle. Babies respond to bottleness or bottlehood also, and can learn many things about bottlehood ; for instance, they can come to associatebottlehood with milk , or with the word ' bottle' . Now imagine a portion of bottle experiencethat we would conceptualizeas three bottles. The infant would also expect to obtain milk (indeed, more milk ) from this bottleness and could also refer to it with the word ' bottle ' . Note that shape is important to the identification of bottlehood, just as the shape of the individual grains is important for distinguishing riCefrom spaghetti from macaroni. Similary, even if Mama is a scattered portion of what goes on, shape is important for distinguishing Mama from Rover or from Papa. That shape is important for distinguishing what scattered portion of experienceconstitutes bottlehood does not mean that the baby is capable of representing' a bottle ' , ' two bottles' , or ' the same bottle I had yesterday'. Thus, demonstrations that toddlers are sensitive to shape in inductions of word meanings when new words are ostensively defined over objects (e.g., Landau, this volume) do not bear on Quine' s proposal. In this discussion I will not make contact with Quine' s radical philosophical views such as the indeterminacy of translation. I assumethat we can characterize the adult ' s onto logical commitments, that these include middle' sized physical objects, and that words such as ' table' , ' dog' and ' person , ' function as sortals in the adult lexicon, in Wiggins ( 1980) sense. Sortals refer to kinds of individuals (i.e., divide reference), providing conditions for individuation (establishing the boundaries of entities) and for numerical identity (establishing when an individuated entity is the same one as one experiencedat someother time, or in somecounterfactual world ) . One way of ' stating Quine s hypothesis, as I construe it , is that babies and toddlers represent no sortal concepts, no concepts that provide conditions of individuation and numerical identity , no concepts that divide reference. Two reviewers of this paper raised the objection that representations of shapes presuppose representations of individuals that have those shapes, ' claiming therefore that Quine s proposal (at least as construed above) is ' incoherent. This is not so. Pleasedwell on the spaghetti, macaroni case. It s

S. Carey I Reconceptualizingthe world

true that if the contrast between the two types of stuff is basedon the shape differencesof individual pieces, then some representationof those individual pieces must enter into the representation of shape. But our concepts of spaghetti and macaroni (and the words spaghetti, macaronI) do not quantify over those individuals. Similarly , we can represent the shape of a scattered portion of sand, arranged, for example, into an S, and when we refer to it as ' ' ' 'a portion or an S we are quantifying over that individual . But when we ' ' think of it as sand, we are not. Quine s proposal is that the child s conceptual/ linguistic system has only the capacity to represent the world in terms of ' concepts like furniture , sand, bottlehood. Of course the child s perceptual system must pick out individuals in order to represent shape, to determine what to grasp, and so on. This is part of what Quine meant when he claimed ' ' that the child is inherently body minded (Quine 1974) . Piaget, like Quine, believed that that baby must construct the concept of enduring objects, although he differed from Quine as to the' mechanismshe envisioned underlying this construction. Quine saw the child s mastery of the linguistic devices of noun quantification , the machinery by which natural languagessuch as English manage divided reference, as the' processthrough ' which the child s ontology comes to match his or her elders . Piaget held that the baby constructs the concept object during the course of sensori -motor development by the age of IS-months or so, and that this construction is the ' basis for the child s mastery of natural language. Since Piaget did not frame his discussion in terms of an analysis of the logic of sortals, it is not clear when he would attribute full sortals to the child. 1 ' The Quine/Piaget conjecture about the baby s representational resourcesis a serious empirical claim, and as I will show, it is difficult to bring data to ' bear on it . In what follows , I first consider Quine s views, contrasting his hypothesis that children come to represent sortals only upon 'learning the' linguistic devicesof noun quantification with what I will call the Sortal First hypothesis. The Sortal First hypothesis is that babies represent sortal concepts, that toddler lexicons include words that expresssortals, and that these representations underly the capacity for learning quantifiers rather than resulting from learning them. I then turn to early infancy, and explore the contrast betweenthe Quine/Piaget hypothesis and the Sortal First hypothesis as regards the earliest phases of word learning. A preview of my conclusions: whereas the Sortal First hypothesis is ultimately favored, evi1 For example, Piaget thought that the logical prerequisitesfor representingthe adult concepts all and someare not acquired until after age S.

S. CareyI Reconceptualizing theworld

147

denceis presentedfor a decidedly Quinian discontinuity in infant conceptual development.

's mastery Thetoddler

of

syntax

' Quine s hypothesis is that the child masters the logic of sortals through a processof adjusting the meanings of nouns and of natural language quantifiers to each other (scrambling up an intellectual chimney, the walls of which are the child ' s currently worked out representationsof the quantifiers he/ she knows). To address Quine' s conjecture experimentally, we must first know when in the child ' s life the putative scrambling is going on. Even by age 3 the child is not producing all the quantifiers that constitute the sides of Quine' s chimney. The very beginnings of the English count/ mass distinction are masteredin the months leading up to age 21/. 2. Many children age 2:0 produce nouns with no determiners or plurals, but some have begun to produce plurals and a few determiners and quantifiers (usually possessivessuch as ' ' ' ' ' ' my , plus a and the ) . Many 2-year-olds beginning to use determiners do not distribute them differently according to the noun' s count/ mass status in the adult lexicon. They still omit many determiners, and use others like ' the' and ' my' that do not differentiate count nouns and mass nouns. By 21.J2 ' virtually all children distinguish in some ways the syntactic contexts in which words like ' table' and ' dog' appear from those in which words like ' water' and ' playdoh' appear (Gordon 1985, Sola et al. 1991) . Gordon ( 1982) showed that between 21/. 2 and 3 years of age the distinction becomes marked in ' syntax, as the child s speechabruptly comes to reflect the arbitrary rule that detenniners are obligatory for singular count nouns, but not for mass nouns ' ' ' .' (that is, one can say I like juice , but not 1 like dog ) . The developmentalfacts summarizedabove determine the relevant agesfor an empirical test of Quine' s speculations. Data bearing against Quine' s claims could be of several types: e.g., data showing children age 2 or under take proper nouns to refer to individuals of a kind or that they take count nouns to refer to kinds of individuals. But, as already mentioned, the trick is ' ' ' figuring out how we can know whether toddlers Mama refers to entities ' ' they conceptualize as individuals or whether their bottle divides reference, referring to each individual of a certain kind , as opposed to bott/ehood. Another type of evidencecould be relevant. If it can be shown that upon first learning ' a' or the plural ' -s' , toddlers interpret them correctly, as signalling an individuated entity of a kind or a plurality of individuals of a

148

theworld S. CareyI Reconceptualizing

kind , respectively, this would tell against Quine. This is becausetheseare the first relevant quantifiers the child learns. If he or she interprets them correctly from the beginning, the interpretation could not have been acquired through an adjustment process involving the entire set of quantificational devices of noun syntax. This last point is important . In the beginnings of language ' learning, on Quine s view, children will not interpret those few quantifiers in their lexicons as adults do. The scramble will have just begun. Data showing ' that children use ' a' and plurals will not be itself relevant to Quine s hypothesis; it must be shown that such quantificational devicesare doing the samework as they do in the adult language.

3. The composition of the toddler lexicon

' A large proportion of the baby s first words are words for middle-sized ' ' ' ' ' ' ' ' ' ' physical objects, such as bottle , book , dog , cup , and banana . But that babies have words in their lexicons that refer to object kinds in the adult lexicon tells us nothing of what these words mean to the babies. Many have argued that the earliest words are often complexive (e.g., Bowerman 1978, Dromi 1987, Vygotsky 1962). That is, children appear to extend words to new referentson the basisof any of the salient perceptualproperties of the original experiencesin which the word was heard. These complexive uses often cut ' ' across what are for adults distinct ontological categories, as when paper apparently refers to the act of cutting, the act of drawing, to pens and pencils and to paper (Dromi 1987). If such complexive uses reflect unconstrained (from the point of view of adult lexical categories) projection of word ' meanings, Quine s views receivesupport . But it is important to seethat such ' complexive usesare not necessaryfor Quine s conjecture to be correct. Indeed, others deny that toddlers construct complexive meanings; Huttenlocher and Smiley, 1987, for example, presentevidencethat from the beginning ' ' babiesuseeach word for middle-sizedobjects appropriately: bottle to refer to bottles, ' book' to books, and so on. But even if Huttenlocher and Smiley are ' right , this fact .does not disconfirm Quine s conjecture. In fact, Quine presupposes that the baby usesthe words in contexts adults would. His point is that, ' evenso, the baby might not be individuating the words referentsas we do. The baby could refer only to what we conceptualize as bottles when she uses ' bottle' but could be , referring to bottlehoods. She could be using the word to refer to a scattered portion of what goes on, determined by perceptual ' ' similarity to the portions of her experiencewhen adults use bottle .

S. Carey I Reconceptua/izing the world

4. Toddler se. itivity to noun syntax

Children as young as 17 months (at least girls that young) are sensitive to the syntactic context in which a new noun is heard in their projection of noun meaning (Katz et al. 1974, Macnamara 1982) . Specifically, if ostensively taught a new word in a count noun context, referring to an unfamiliar doll . ( See this. This is a dax. Can you touch the dax? Can you put the dax on ' your head ... ), they assumethat other dolls of the sametype are also daxes. But if taught in a proper noun context (.Seethis. This is Dax. Can you touch Dax. Can you put Dax on your head ...' ), they assumethat other dolls of the sametype are not Dax , reserving ' Dax ' for the original doll only . Do thesedata establish that young children distinguish kinds from individuals , and use count nouns to achieve divided reference? Certainly not. They do establish that toddlers are sensitive to the syntactic distinction between nouns following determiners and those not following determiners, but this distinction could be signalling a different semantic distinction than that between individuals and kinds. For a sample Quinian interpretation : babies ' ' ' ' could take nouns without determiners such as ' Dax , ' Rover , and Joan , to refer to portions of experiencedefined by a stricter similarity metric than that referred to by nouns with determiners. Supposea Quinian baby, Alice , has a ' ' ' ' brother whom she hears called both Rupert and a boy . Supposealso that she relies on shape to determine Rupertness and boyness. She could have ' ' learned from others' usage of the words that to be called Rupert , a given portion of experiencemust be very similar in shapeto the original portions of ' ' experienceto which the term was heard to refer, whereasto be called a boy , ' .the boy , something need look only somewhat like the original referent. A ' ' ' ' generalization of this pattern of distinction , across Alice and a baby , ' and so on could .Rover' and ' a , , underly the patterns of projection dog , found by Katz et al., 1974, and subsequentreplications. This interpretation of the Katz et al. data attributes to the baby a different ' ' ' ' ' ' meaning for a from the adult as well as different meaningsfor bottle , boy , ' ' . Rupert . This is, of course, Quine s position . On his view, it is only in the course of learning other quantifiers, plural markers, and so on, and adjusting to all the contrasts in usage they mark (the process of scrambling up the ' ' intellectual chimney cited above) that the baby works out the meaning of a , ' ' ' ' ' ' ' ' ' ' ' . ' .the another some more all , , many , same,2 etc. , , , 2 Bloom. personal communication, provides the following argument against the Quinian ' interpretation of the Katz et al. data. Among children s very first words are some pronouns (e.g.,

In several studies, my colleaguesand I have attempted to addressQuine' s ' proposal by comparing children s representations of solid physical objects, such as cups, with their representationsof non-solid substances , such as sand . is since adults or gels or creams Our idea that conceptualize the former as kinds of individuals (i .e., in terms of sortals that divide reference), but do not conceptualize the latter in this way, we might be able to find evidence that infants and toddlers respect the quantificational distinction between the two as well. In the first studies, Sola et al. ( 1991) compared 2-year-olds' projection of newly learned :words ostensively defined by reference either to novel solid physical objects (e.g., a brass plumbing T) or novel non-solid substances(e.g., a hair-settin$ gel with grapenuts embeddedin it ) . The objects were made of unfamiliar materials and the non-solid substanceswere presentedformed.into distinctive novel shapes. The child was introduced to the novel entity and ' ' ' ' provided a word for it (e.g. blicket for a novel object; stad for a novel nonsolid substance). The child was then presented two new sets of stimuli and asked to give the experimenter the blicket or the stad. For each object trial , the choicesconsistedof another object of the same shapemade of a different material (e.g., a plastic plumbing T) or three small pieces of the original material (brass) . For each substance trial , the choices consisted of a new substanceformed into the original shape, or three small piecesof the original substance. Figure I shows the design for one trial of each type. There were four object trials and four non-solid substancetrials. Of course, which words were assigned to which entities varied across subjects, but for expository ' ' ' ' clarity I will use blicket as my sample object name and stad as my sample non-solid substancename. ' ' ' he' ' it ' and thesearetreatedfrom theonsetas , ) belongingto the samecategoryas Rupert and ' ' not as dog . Childrendo not usethemwith determinersor modifiers(Bloom 1990 ). The adultlike , denote analysisworks well in accountingfor this finding; pronouns, like proper names individuals. But the Quiniananalysisfails, sincea far broaderrangeof referentsare called' it ' or ' he' than are called'dog' . I agreewith this argument, as I rejectthe Quinian proposalin . However, Quinecould reply that the child hastwo setsof favor of the Sortal First hypothesis words: wordslike ' dog' and wordslike ' Rupert', and a few singularitieslike ' he' , eachtagged with someof the syntacticcontextsin which they appearand eachtaggedwith prototypical . Comingto recognizethat the syntactic referentsand a similarity metric that determinesusage contextsin which ' he' appearsare the sameas those for ' Rupert' might be part of the . scramblingprocess

S. Carey /

the world 8U~ dCEftW .

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' Sola et al. carried out two analysesto assesswhether children s representations of the referents of the words were influenced by the status of their knowledge of count/ mass syntax. First , they collected production data and assignedeach child a value corresponding to the degreeto which count nouns and mass nouns appeared in selective syntactic frames (e.g., ' a NO U N ' , ' NO UNs ! ' ' too much NO U N ' . Scores ran from 0 to near 1.0. Second , they ) introduced the new words in two different ways. In the neutral syntax condition , no syntactic information as to the count/ mass status of the word was provided ; the words were introduced as ' my blicket , my stad' and ' ' subsequentlyappearedin the context the blicket , the stad . In the informative ' ' syntax condition , the words were introduced as a blicket , some stad , and ' further differentiated syntactically, e.g. another blicket , some more stad' . As figure 2 shows, children at age 2:0 and 2:6 used different basesfor their projection or words for the two different types of entities. They projected ' biicket' to the other whole object the sameshapeas the original referent and ' stad' to the scattered portion of substancethe same texture they projected and color as the original referent. For object trials , children were sensitive to matchesin shapeand number; for non-solid substancetrials , children ignored matchesin shapeand number. Performancewas more adult-like on the object trials, but performance on both types of trials was better than chanceat both ages. Also apparent on figure 2, the syntactic context made no difference. The children were no more likely to interpret ' blicket' as the word for a kind of individual when it was heard in a count noun context. Similarly , hearing

S. Carey / Reconceptualizingthe world % choicesmatchingreferentin shapeandnumber

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' stad' in a massnoun context made them no more likely to conceptualizestad as a substancethat can appear either in scatteredor singly bounded portions . Further , the child ' s productive control of count/ masssyntax did not influence the pattern of projection : children with differentiation scoresof 0 showed the samepattern as those with differentiation scoresclose to 1. ' We can conclude from these results that an entity s status as a solid physical object (or not ) influences which of its properties are salient in determining what other entities are referred to by the sameword. We can also conclude that this distinction between objects and non-solid substances predates mastery of count/ mass syntax. These data are consistent with the ' ' ' Sortal First hypothesis, for they are consistent with the child s taking blicket ' ' to refer to each individual whole object of a kind , and stad to refer to a kind of substance, conceptualized as a non-individuated entity . But the data are ' also consistent with the following more Quinian interpretation of the child s representationsof the blicket and the stad. ' Babies, being ' body-minded (Quine 1974) could be sensitiveto the perceptual experiencesthat determine objecthood: boundedness, rigidity , coherence through motion . Whenever theseare detected, they could heavily weight such . Shape would features as shape in their representation of these experiences

S. CareyI Reconceptua/;zing the world

thus be a salient feature of the blicket , but not of the stad, for non-solid substancesdo not maintain their shapeswhen manipulated. For non-solid substances , properties such as texture and color might be salient, for these constant over experienceswith substances . In other words, the two -yearstay old could be using ' blicket' to refer to blicketness, and recognize blicketness by shape. The differential patterns of projection do not establish that the toddler is using ' blicket ' to refer to any individual whole object of a certain kind , that the toddler divides the referenceof ' blicket ' . One detail of the data from figure 2 favors the Sortal First over the Quinian interpretation, and that is that toddlers performed more like adults on the object trials than on the substancetrials. Quine' s interpretation of this would have to be ad hoc, perhaps that the baby has had more object experiencethan substanceexperience. But the Sortal First hypothesispredicts this asymmetry. To seethis, supposethe Sortal First hypothesis is true, and ' ' suppose that upon first hearing the word blicket the child assumesthat it refers to each individual object of a certain kind . The choicesfor testing how the child projects ' blicket ' included another si.ngle object, and 3 small objects. Even if the child isn' t exactly sure of which features of the blicket establish its kind , the child can rule out that the 3 small objects are a blicket , for under no interpretation can they be an individual object of the same kind as the original referent. Children should then be at ceiling on the object trials , which ' ' they are. .The substancetrials are another story. If upon first hearing stad , the child takes it to refer to the kind of substanceof the original referent, then scatteredportions have no different status from unitary portions . There is no clue from number of piles which of the choices on the test trials is the stad. If children are not certain what properties of the original sample of stad determine the kind stad, they might do worse on the stad trials. And indeed, they do. The key issue here is the role of number in determining how to project ' blicket' . If the Quinian interpretation of the data is correct, the baby should ' blicket' on the basis of project shapesimilarity , no matter whether the choice that does not match in shapeconsists of one object or three objects. That is, the baby should succeedon an object trial as on figure 3 as well as on an object trial as in figure 1. The Sortal First interpretation predicts that performance on the object trials will fall to the level of performance on the substancetrials if the cue from number is removed (figure 3) . In an object trial such as that on figure 3, ' blicket' is ostensivelydefined as before, but the choicesfor projection are changed: another blicket of a different material (as before) and another whole object of . a different kind made of the same

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trialin Sola(1987 ). Fig. 3. Object material as the original referent (instead of the three small objects) . Now the child has no clues from number of objects as to which is the correct choice. Performanceshould fall to the level of the substancetrials , and indeed, this is what happens(Sola 1987) . Apparently , the child uses the information provided by number on the object trials , but not on the substancetrials. We take this as evidencethat the child conceptualizessomeentities as individuals (such as kinds of objects) and conceptualizesother entities as non-individuated (such as kinds of substances ) . These distinct ways of conceptualizing objects and substancespredates ' ' mastery of count/ masssyntax. Toddlers do not merely project blicketness on the basis of shapeof individual piecesof blicketness, as we determine whether somepasta is spaghetti on the basis of the shapeof individual pieces. Instead, ' ' the pattern of projection suggeststoddlers divide referenceof blicket , and take it to refer to any individual of a certain kind .

' ' ' ' ' 6. Toddlers understand i Dgof 8 , someNOUN_ I take the data reviewed in the previous section to show that by age 2:0 children take ' blicket ' to refer to individual objects of a certain kind and ' stad' to refer to non-solid substancesof a kind and that the toddlers' , representationsof blickets and stads have the same quantificational structure ' ' as would adults . ' Blicket is a sortal term. These data disconfirm Quine only on the assumption that the baby did not acquire these representationsfrom

S. Carey / Reconceplualizinglhe world

learning English noun quantifiers. This assumption seemswarranted, given that as a whole toddlers at 2:0 do not produce quantifiers, and given that the pattern of projection was independent of whether the individual subjects produced any noun quantifiers selective for count nouns. A worry , though , is that babies may have better comprehension than production of the quantifiers. We attempted to address that possibility by manipulating the syntactic context in which the word appeared. As mentioned above, the syntactic environment in which the new word appeared had no effect in Sola et alis experiments, even at age 2!j2 when many children did produce quantifiers differentially for what are count and mass nouns in the adult lexicon. The Quinian interpretation of this fact is that quantifiers like ' a' , ' another' , ' some NOUN _ ' , ' some more NOUN _ ' do not yet signal the distinction between individuated and nonindividuated entities, just as the child is not projecting ' blicket' and ' stad' on the basis of that distinction . The Sortal First interpretation : objects are naturally construed as individuals of a kind and non-solid substances are naturally construed as non-individuated entities, even by toddlers, as shown by performance in the neutral syntax condition . Informative ' syntax merely reinforces the child s natural construal of the two types of entities. A study by Sola ( 1992) decided betweenthesetwo interpretations, and also establishedthat our production data did not underestimatetoddlers' interpretation of the quantifiers. Sola taught toddlers words for the objects and substancesin a new condition : contrastive syntax. ' Blicket' was introduced in a mass noun context ; ' stad' in count noun context. That is, when shown a novel solid object, the child was told , ' Here' s some blicket ... Would you like to seesome more blicket?' And when shown a non-solid substancefashioned into a distinctive shape, the child was told , ' Here' s a stad ... Would you like to seeanother stad?' As can be seen from figure 4, at both ages 2 and 2!j2' the pattern of projection was markedly different from that seenin the neutral and informative syntax conditions (figure 2) . At both ages, the syntactic context ' some NOUN _ ' , ' some more NOUN _ ' made children slightly less ' ' likely to construe blicket as referring to an individual whole object of a kind . There was a slight tendency towards interpreting it to mean something like brass. The syntactic context ' a stad' made children significantly less likely to construe the non-solid substance as a non-idividuated entity . Rather, they interpreted the word as meaning something like s-shapedpi /e. Wait , you might say, doesn' t this show that children at theseagesdo know the force of ' a' , ' another' , and so might have learned to represent sortal

S. Carey I Reconceptualizingthe world

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concepts in conjunction with bootstrapping the meaning of the quantifiers? No , becauseof one further aspectof the data. At the younger age, sensitivity to conflicting syntax was shown solely by those children who had differentiated count and mass nouns in their production . Those whose differentiation scoreswere low performed just as did toddlers in the informative and neutral conditions, projecting ' blicket' to the other object of the same kind as the ' ' original referent and stad to the other substanceof the same kind as the ' ' original referent. This shows that the interpretation of blicket as a sortal ' ' ' ' predateslearning the meaning of a , another , and presumably underlies the latter achievement, as predicted by the Sortal First hypothesis. ' ' These data tap the very moment children first learn the meaning of a . 's They have only begun the scramble up Quine chimney, and have not had ' ' time to adjust their interpretation of ' a' to many other quantifiers. Yet , a signals an individuated entity of some kind . Together these data provide converging support for the Sortal First hypothesis. The child naturally

S. CareyI Reconceptualizing the world

157

construes physical objects as individuals in distinct kinds , and naturally construes non - solid substances in terms of kind of non - individuated entities . These natural construals support adult - like projection of word meaning (figure 2), and support adult - like interpretation of newly learned quantifiers ' ' ' ' like a , some and plurals .

YGungerinfants ' Altogether the data support the Sortal First hypothesis over Quine s conjecture, but they do not establish when the child first begins to represent sortal concepts. As noted earlier , it is not clear when Piaget would attribute sortal concepts to children , but it is certain that he would deny them to young infants . The argument I have developed so far does not bear on Piaget' s claims about the representational capacities of infants , as it concerns children age 24 months and older . Of course, a demonstration that young infants represent sortal concepts would defeat ' ' ' Quine s conjecture as well as Piaget s characterization of the infants conceptual resources. Studies by Cohen and his colleagues(e.g., Cohen and Younger 1983) show that quite young babies will habituate when shown, for example, a seriesof distinct stuffed dogs, and that they generalize habituation to a new stuffed dog and will dishabituate when shown a stuffed elephant. Similarly , when shown a seriesof distinct stuffed animals, babies of 8 or 9 months habituate, generalize habituation to a new stuffed animal, but dishabituate to a toy truck. Do thesedata not show that babies of that age representconceptssuch as ' dog' and ' animal?' Certainly not. Babies may be sensitive to dog shapes or animal shapes; babies may be habituating to doghood or animalhood. To credit the baby with sortals such as ' dog' , or ' animal' , we must show that such concepts provide the baby with criteria for individuation and identity . My discussion of this question has two steps. First , I argue that babies represent at least one sortal , object. Second, I present some recent data from my lab that suggest that as late as 10 months of age, the baby may have no more specific sortal concepts - not cup, bottle, truck , dog, animal .... Thus, a Quinian interpretation of the above habituation data may well be correct.

S. Carey I Reconceptualizingthe world

8. Principles of individuation : Yo UDger infants

' ' Piaget s characterization of infants cognitive capacitieswas basedon tasks in which the baby must solve some problem, often involving means- end ' analysis, and often involving planning some action. For example, Piaget s conclusions that babies do not represent objects as continuing to exist when out of view were basedon the robust finding that babies under 8 or 9 months ' cannot remove a cover to get a hidden object. The babies failure might be due to their failure to realize the object still exists, as Piaget thought , or equally might be due to their inability to carry out one action (remove a cover) to achievesome other goal (obtain the object). What is neededis some reflection of the baby' s conceptualization of the world that relies on behaviors well within the repertoires even of neonates. Over the past 15 years or so, such a method has been developed and is now very widely used. It relies on babies' ability to control what they attend to. The basic idea is simple. Under most circumstancesbabies will look longer at what is unfamiliar or unexpectedcompared to what is familiar or expected. Researchersuse this fact to diagnosehow the baby representssome situation , especiallywhat the baby considers surprising given his or her current state of physical knowledge. The selectivelooking paradigm has been usedextensively to probe babies' representations of objects, and the data from a subset of thesestudies can be recruited to bear on the question at hand. They establish that by four months of age the baby representsat least one sortal concept the concept of a physical object. The baby has criteria for individuation and for numerical identity of objects. Spelke and her colleagueshave shown that babies establish representations of objects on the basis of criteria which individuate them - an object is a coherent, bounded, entity that maintains its coherenceand boundaries as it moves through space(seeSpelke, 1990, for a review) . The baby predicts the motion of objects according to principles such as that one object cannot pass through the spaceoccupied by another (Spelke et al. 1992, BaillargeoD 1990) . Most relevant to the present discussionare studies showing that babies count objects. These are of two types. In the first , babies are simply presentedwith arrays containing a fixed number of objects, say 2 of them, one after another. For example, two cups, followed by two shoes, two bottles, two hats, two pens, and so on. The pairs of objects are never repeated, so the arrays have nothing ' in common but twoness. The baby s looking is monitored , and after a while, ' s attention to each new the baby , relative to his or her array decreases

S. Carey I Reconceptualizingthe world

original looking time. The baby is getting bored. After looking time has decreased to Y2 its original level, the baby is presented with an array containing one object, or three objects. In both cases, looking time recovers to its original level. The baby notices the difference between two objects, on the one hand, and a single object or three objects, on the other. This result, or one very like it , has been obtained with neonates(Antell and Keating 1983) . In fact, the baby' s capacity to detect similarity in number across distinct arrays serves a methodological wedge into the problem of how babies individuate objects. The baby can be habituated as described above, to two objects, and then presented with an array as in figure 5, consisting of two distinct objects sharing a common boundary. Babies dishabituate to this array, showing that they perceiveit as one object, rather than two. Thesedata support the conclusion, derived from other types of data as well, that babies are not sensitive to shape or texture regularity in individuating objects; they needpositive evidenceof distinct boundaries, such as one object moving with ' respectto the other, or the objects being separatedin space.

..:..~ .111 ,.:~ ;1 ~ : 111111 . ~

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A second source of evidence that babies count objects derives from data showing that babies can add and subtract. Wynn ( 1992) showed four -month olds events in which a secondobject was added to an array already containing one object. An object was placed on an empty stage while the baby watched and then a screen was raised that covered the object. A hand carrying a second object was shown going behind the screen and returning empty. The screenwas then lowered, revealing either one object (unexpected outcome, even though that was what the baby had last seen) or two objects (expectedoutcome, if the baby knows I + I = 2) . Babies looked longer at the unexpectedoutcome. A further experiment showed that babies expected exactly two objects, rather than simply more than one object. In this study, the expectedoutcome was two objects, as before, but the unexpected outcome was three objects. Again , babies were bored at seeing two there, and looked longer at the

S. Carey / Reconceptualizingthe world

unexpectedoutcome of three objects. Experiments of the same sort demonstrated that babies expected3 - I to be 2, and 2 - I to be I . Whereas these studies were performed to explore the baby' s concept of number, they bear on our question as well. Babies, like anybody, cannot count unlessthey have criteria that establishindividuals to count. Babiesclearly have criteria that establishsmall physical objects as countable individuals.

That babies individuate and count objects does not show that they trace identity of objectsthrough time, that they have the representationalcapacity to distinguishone object seenon different occasionsfrom two numerically distinct similar objects. However, there are now two demonstrationsof but physically ' this capacity in infants age 4 months or younger. Spelke( 1988) showedbabies , screenA to objectsmoving behind and r~ erging from two separatedscreens the left of screenB (figure 6). An object emergedto the left of screenA and returned behind it, and then an object emergedto the right of screenBand returned behind it. At any given time, at most one object was visible, and no object ever appeared in the space between screensA and B. Under these conditions, 4-month- olds inferred there must be two objects, as shown by the fact .that when the screenswere removed, revealing two objects (expected outcome), they looked less than when the screenswere removed revealingone object (unexpectedoutcome). Baillargeon ( 1990) showedinfants two objects at once, one on either side of a screen. The babiesthen used the existenceof two numericallydistinct objectsto make senseof what would be an impossibleevent if only one object were involved. Togetherthesestudiesshow that babiesusetwo spatiotemporalprinciples to individuate and trace identity of objects: one object cannot be in two placesat the same time, and one object cannot go from one p}a(' e to another without tracing a spatiotemporallycontinuous path. In sum, infants have a concept physical object that functions as a sortal ; they have at least one concept that divides reference, that provides criteria for individuation and numerical identity . These criteria are spatiotemporal.

differencebetweenyounginfantsandadults 10. A majorconceptual Adults also look longer at the unexpected events in the experiments described above. Further , they ask how the magic tricks are done. This is

S. CareyI Reconceplualizing lhe world DiscontinuousCondition

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becauseadults use spatiotemporal information in just the sameway as do the infants. But adults use other types of information in establishing individuals and tracing their identity through time: property information and membership in kinds more specific than physical object. We use property information - if we see a large red cup on a window still , and later a small green cup there, we infer that two numerically distinct cups are involved, even though we have no spatiotemporal evidenceto that effect. And , as philosophers point out , our identity judgements are relative to sortals more specific than object (Wiggins 1980, Hirsch 1982, Macnamara 1986) . Imagine a junk car, consigned to the crusher. The process of crushing is a spatiotemporally continuous ' , gradual process. Any changes in the car s properties are also continuous ; it changesshapecontinuously, for example. Yet we say that at a certain point the car goes out of existence, and is replaced by a lump of metal and plastic. We trace identity relative to kinds more specific than object, kinds

S. Carey I Reconceplualizingthe world

such as car, person, tab/e. Such concepts (sortals), typically lexicalized as count nouns in languages that have a count / mass distinction , provide additional criteria for individuation and identity to the spatiotemporal criteria that apply to bounded physical objects in general, and to the general ' assumption that an object s properties stay stable over time, or change continuously. When a person, Joe Shmoe, dies, Joe ceasesto exist, even ' though Joe s body still exists. The sortal person provides the criteria for ' ' identity of the entity referred to by the name Joe Shmoe . In collaboration with Fei Xu , I have been exploring the question of whether babies represent any sortals more specific than object, or whether babies can use property/ kind information to individuate and trace identity of objects ( Xu and Carey 1993) . Consider the events depicted in figure 7. An adult witnessing a truck emerge from behind and then reenter a screen and then witnessing an elephant emerge from behind and then reenter the screen would infer that there are at least two objects behind the screen: a truck and an elephant. The adult would make this inference in the absence of any spatiotempotal evidence for two distinct objects, not having seen two at once nor any suggestion of a discontinuous path through space and time. Adults trace ' ' ' ' identity relative to sortals such as truck and elephant and know that trucks do not turn into elephants. Xu and Carey ( 1993) have carried out four experiments based on this design. Ten-month -old babies were shown screensfrom which two objects of different kinds (e.g., a cup and a toy elephant, a ball and a truck ) emerged from opposite sides, one at a time. Each object was shown a total of four times. After this familiarization , the screenwas removed, revealing either two objects (expected outcome) or one object (unexpected outcome). In all four studies, babies looked longer at the expectedoutcome. They could not use the difference between a cup and an elephant to infer that there must be two objects behind the screen. Another group of IO-month -olds was run in a parallel version of this study basedon Spelke's design (figure 6) . That is, babies were shown two identical objects emerging from the two screensa total of four times each, and the timing of the eventswas the samein the one screen/two kinds studies. Babies succeeded , looking longer at the unexpectedoutcome of one object. Apparently , babiescan use spatiotemporal information to individuate objects before they can use kind information . We have ruled out severaluninteresting interpretations of the failure in the property/ kind conditions of these studies. For example, it is not that babies

S. Carey I Reconceplualizillgthe world Different

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do not notice the difference between the two objects. In one version of the study, babies were allowed to handle each object (one at a time of course, for we didn ' t want to provide spatial information that there were two ) before beginning the events. This made no difference to the results. In another, we compared looking time to the familiarization events when the objects are of different kinds (e.g., a cup and an elephant) to looking times during familiari zation in a condition where the objects emerging from each side of the screen are of the same kind (e.g., two elephants) . Babies habituated much faster in the latter condition . That is, they noticed that the elephant and the cup are different from each other. After habituation, we removed the screen, revealing either one object or two objects. Babies in both conditions (cup/elephant; elephant/ elephant) looked longer at the outcomes of two objects (unexpected in the elephant/ elephant condition ; expected in the elephant/ cup condition ) . The preference for two objects was equal in the two conditions. Thus, although babies notice the difference between the elephant and the cup, they

S. Carey I Reconceptualizingthe world

simply do not use this information to drive the inference that there must be two numerically distinct objects behind the screen. In appears, then, that in one senseQuine was right . Very young infants have not yet constructed concepts that serve as adult -like meanings of works like ' bottle ' , ' ball ' , and ' dog' . How are the babies representing these events? We can think of two possibilities. First , the babies may actually establish a representation of a single individual object (O BJECTi ) moving back and forth behind the screen, attributing to this object the properties of being yellow and duck-shaped at some times and white and spherical at other times. The basis for such a representation could be spatiotemporal : the infants may take the oscillating motion as a single, continuous , path . A second possibility is that the baby is making no commitment at all concerning whether the objects emerging to the left and right of the screen are the same or different. That is, the baby is representing the event as OBJECT emerging from the left of the screen, followed by OBJECT emerging from the right of the screen, and represents these neither as a single object (O BJECTi ) nor as distinct objects (O BJECTi , O B JECTj ) . Supposeyou seea leaf on the sidewalk as you walk to class, and you seea leaf on roughly the same place on the sidewalk as you return from class. That may be the same leaf or it may not ; your conceptual system is capable of drawing that distinction , but you leave the question open. If the infant is leaving the issue open in this case, then why does he/ she appear surprised when the screens are removed and two objects are revealed? On this hypothesis, the longer looking time at two objects is a familiarity effect; the infant has been familiarized with instances of single objects, and thus seeing ' ' two objects is different . After all , babies can be habituated to oneness by being shown a series of objects, one at a time. Even if you were not sure whether that leaf was the same as the one you had seen earlier , if you returned to the classroom later in the day and encountered two leaves on the sidewalk, you would see this state of affairs as different from ones in which you encountered casesof single leaves on the sidewalk. We do not know which possibility is correct. The baby actually may be representing the events as if a duck-shaped object is turning into a ball shaped object (possibility one) or simply may be failing to establish representation of two distinct objects (possibility two ) . The take-home message is the samewhichever possibility is correct ; IO-month -old infants do not use the property/ kind differences between a red metal truck and a gray rubber elephant to infer that there must be two numerically distinct objects involved in the event.

S. Carey/ Reconceptualizing the world

At II months , about half of the babies we test succeed at our task. When babies do succeed, are they doing so on the basis of kind information or property information ? That is, are they representing the events as do adults , as involving a duck and a ball , or are they individuating the objects on the basis of property differences? Further experiments could bear on this question . For example, habituation studies show babies to be sensitive to color changes and size changes, but color and size are not the types of properties that signal kind differences, at least in the adult conceptual system. Would babies of the age succeeding at this task be as likely to infer two objects when shown a blue and red cup, or a big and small cup , emerging from either side of the screen, as when shown a blue cup and a blue elephant of equal sizes emerging from either side of the screen? A difference in success rate favoring the latter pair would be suggestivethat babies, just like adults , come to represent kinds of objects, and individuate objects relative to kinds . These experiments together would provide information about the developmental course of this repres ~ntational capacity . It is significant that babies begin to comprehend and produce object names at about 10 to 12 months of age, the age at which they begin to use the differences between cups and elephants to individuate objects. Again, this pattern of results is consistentwith the Sortal First hypothesis. That is, babies do not seemto learn words for bottlehood ; they begin to learn words such as ' bottle' just when they show evidencefor sortal concepts such as bottle which provide conditions for individuation and numerical identity . Current studies in our lab are exploring the relations between specific words understood and successat individuation basedon the kinds expressedby those words. It is not surprising that babies use spatiotemporal information before kind information to individuate and trace the identity of objects. All physical objects trace spatiotemporally continuous paths; no physical object can be in two placesat the same time. However, what property changesare possible in a persisting object depends upon the kind . An apparent change of relative location of the handle to the body of a ceramic cup signifies a different cup; an apparent change of relative location of a hand to the body of a person does not signify a different person. In sum, these data suggest that babies have at least one sortal concept innately - physical object. Their object concept provides spatiotemporal conditions for individuation and numerical identity . They can use spatiotemporal information to identify individuals in their environment, and can then learn more specific sortals for kinds of theseobjects. Exactly how this is

166

S. Carey uaJizing theworld I Reconcept

is the big question, of course. The presentdata suggeststhat accomplished most of their first yearof life on this accomplishment . they spend II . A few

eRne ' odin! remarks

Where does this leave us vis-a-vis the continuity assumption? The major discontinuity posited by Quine and Piaget does not receive support; there is no reason to think that babies lack the logical resourcesto representsortals, and indeed, object functions as a sortal at least from 4 months on. But if the interpretation of the Xu and Carey data suggestedabove is correct, then an important Quinian discontinuity is supported. Babies may be setting up a representation of an object which sometimesis round , white, and styrofoam and at other times red, metal, and truck -shaped. This is a representational systemvery different from yours and mine. My story is not complete. I do not know if Xu and I are interpreting our data correctly. Also , we have as yet no account of the mechanism by which babies might begin to acquire specific sortals at around 11 months. But as I am convinced important conceptual changes occur later in life (cf. Carey 1991, Carey and Spelke, in press), I would not be shocked to find interesting discontinuities in the conceptual histories of infants, even in arenasso closely implicated in languageas the conceptual underpinnings of count nouns.

References Antell , S. and DiP. Keating, 1983. Perception of numerical invariance in neonates. Child Development 54, 695- 701. ' Baillargeon, R., 1990. Young infants physical knowledge. Paper presented at the American PsychologicalAssociation Convention, Boston. Bloom, P., 1990. Syntactic distinctions. Child Language 17, 343- 355. Bowerman, M ., 1978. The acquisition of word meaning: An investigation into some current

conflicts. In: N. Waterson . New York: . C. Snow (eds.). Developmentof communication Wiley. . Knowledgeacquisition: Enrichmentor conceptualchange ? In: S. Carey. Carey. S.. 1991 R. Gelman(eds.). The epigenesis of mind: Essaysin biology and cognition. Hillsdale. NJ: Erlbaum. . Domain specificknowledgeand conceptualchange . In: L. . in press Carey. S. and E. Spelke Hirschfeld. S. Gelman(eds.). Cultural knowledgeand domain specificity . Cambridge . UK : . CambridgeUniversityPress . Perceptual Cohen. L.B. and B.A. Younger. 1983 in theinfant. In: E.K. Scholnick categorization . 197-200. Hillsdale. NJ: Erlbaum. (ed.). New trendsin conceptualrepresentation

ua/izint. the world S. CareyI Reconcept . . Early lexicaldevelopment . London: CambridgeUniversityPress Dromi, E., 1987 . Theacquisitionof syntacticcategories : Thecaseof thecount/massdistinction. Gordon, P., 1982 Instituteof T~ hnology, Cambridge , Massachusetts , MA. Unpublisheddoctoraldissertation . Evaluatingthe semanticcategorieshypothesis : The caseof the count/mass Gordon, P., 1985 distinction. Cognition20, 209-242. . Hirsch, E., 1982 . The conceptof identity. New Haven, CT: Yale UniversityPress . Cognitive . Earlyword meanings : Thecaseofobj ~ t names Huttenlocher , J. and P. Smiley, 1987 . 19 63 89 , Psychology . What's in a name? A studyof how childrenlearn Katz, N., E. Bakerand J. Macnamara , 1974 . Child Development 45, 469- 473. commonand propernames . Namesfor things: A study of humanlearning. Cambridge Macnamara , MA : MIT , J., 1982 Press . . Macnamara . A borderdispute. Cambridge , J., 1986 , MA : MIT Press . Cambridge Pinker, S., 1984 . Languageleamabilityand languagedevelopment , MA : Harvard . UniversityPress . . Word and object. Cambridge , MA : MIT Press Quine, W.V.O., 1960 W. V . . New York: ColumbiaUniversity .0 . 1969 Onto and other , , Quine essays logicalrelativity . Press . . New York: ColumbiaUniversityPress . The rootsof reference Quine, W.V.0 ., 1974 ' inductionof world . UnpubN.N. 1987 . constraints on 2 olds Onto , , meanings logical year Sola Instituteof Technology , MA. , Cambridge .Ilsheddoctoraldissertation , Massachusetts . Inferences aboutthe meaningsof nouns: The relationshipbetweenperception Sola, N.N., 1992 29- 45. and syntax. CognitiveDevelopment . Ontological categoriesguide young children's , 1991 Sola, N.N., S. Carey and E.S. Spelke : Objecttermsand substance terms. Cognition38, 179-211. inductionsof word meaning . In: L. . Weiskranz(ed.), Thoughtwithout E.S 1988 The of , , Spelke : origins physicalknowledge . , 168- 184. Oxford, UK : Oxford UniversityPress knowledge . CognitiveScience14, 29- 56. . Principlesof objectperception , E.S., 1990 Spelke . . Origins of knowledge Macomber and K. Jacobson E.S. K. J. , 1992 , , , Spelke Breinlinger Review99, 605- 632. Psychological . . Cambridge . Thoughtand language , MA : MIT Press Vygotsky, L.S., 1962 . MA : Harvard Press . and substance . D. 1980 Sameness , , , University Cambridge Wiggins . Addition and subtractionby humaninfants. Nature358, 749- 750. Wynn, K., 1992 . Infant metaphysics : The caseof numericalidentity. MIT Centerfor Xu, F. and S. Carey, 1993 . Science Occasional Paper Cognitive

) 169- 196. North-Holland Lingua92 ( 1994

Explanation , association , and the acquisition of word meaning * FrankC. Keil , CornellUniversity , 223 Uris Hall, Ithaca, NY /4853-760/ , USA Departmentof Psychology A newly emerging view of concept structure, the concepts-in -theories view, suggeststhat adult conceptsare intrinsic mixes of two different sorts of relations: (a) those involving domain-general tabulations of frequenciesand correlations and (b) those involving domain-specific patterns of explanation. Empirical results from early cognitive development suggestthat , by the time first words are acquired, most concepts have this intrinsic mix even though changesin the nature of the mix can produce marked developmental changesin apparent concepts, word meanings, and their use. . The concepts-in -theories view suggests that the sorts of constraints needed to model the representation and acquisition of concepts cannot be based solely on either perceptual or grammatical bases; they must also arise from blases given by specific patterns of explanation, patterns that may depart from standard notions of intuitive theories. These in turn suggest different views of possible constraints on the acquisition of word meaning.

I . Introduction

Categorization is one of the most common and salient of human cognitive activities, and many of the categoriesso fonned appear to be shared among individuals, a pattern that is highlighted by the use of common words to refer to those categories. In experimental psychology, the distinctive aspects of mental life that enable each categorization are usually thought of as concepts. Sharedmental structures are assumedto be constant acrossrepeatedcategorizations of the same set of instances and different for other categorizations. When I think about the category of dogs, a specific mental representation is assumedto be responsiblefor that category, and roughly the same representation for a later categorization of dogs by myself or by another. The . Much thanksto two anonymousreviewersand to Dan Simonsfor extensivecommentson . Muchof the research earlierdraftsof this manuscript reportedon in this paperwassupportedby . NIH grant numberROl-HD23922 - 3841/94/$07.00 @ 1994- ElsevierScienceB.V. All rightsreserved 0024 SSDI 0024- 3841( 93) EO049- D

F.C. Keill Wordmeaning

phenomenonof categorization, coupled with the notion that repeatedcategorizations of the samesort are basedon the samemental representation, is the launching point for most psychological investigations of what conceptsare. Categorization, however, must not be equated with heuristics and other procedures that provide rough and ready identification of instancesabove a modest confidence level. Although one might use hair length as a rough means for identifying human sex at a certain confidence level, a careful and deliberative categorization of humans by sex would make little note of such an attribute . Careful, consideredjudgements of membership may emphasize different aspectsof mental structures than the fastest and loosest means of identifying members of categories. In this paper, these different facets of categorization behaviors are considered together in terms of their implications for models of the acquisition and representation of word meaning. Psychologicalresearchon concepts in the last three decadesstarted largely with the phenomenonof categorization, first with teachingartificial categories , and later with the study of more naturally acquired ones. But psychological viewsof conceptshave undergonetwo dramatic shifts, initially as a consequence of uncoveringmore details on categorizationbehavior, but increasinglyalso as a , measuresthat are starting to consequenceof using other behavioral measures raise questionsabout what conceptsare in the first place. My purpose here is to explore the consequences of the most recent shift for word meanings. I will argue for the following points : ( I ) The currently emerging view, the concepts-in -theories view, must ultimately characterizeadult conceptsas intrinsic mixes of two different sorts of relations: (a) those involving domain-general tabulations of frequencies and correlations, such as done by associative models and many connectionist systems, and (b) those involving domain-specific patterns of explanation, usually of a causal nature. 2 ( ) Empirical results from early cognitive development and first word meanings suggestthat by the time the first words are acquired, most if not all conceptshave this intrinsic mix even though changesin the nature of the mix can produce marked developmental changes in apparent concepts, word meanings, and their use. 3 ( ) The intrinsic mix and its early appearancesuggestsa different kind of ambiguity in word meaning, wherein largely overlapping setsof instances have the same label .applied to them but have different meanings, allow different patterns of induction , provide different categorizationsof critical test cases. Unlike classical lexical ambiguities there is no dramatic change in the class of referents even as there is a discrete change in meaning.

F.C. Keill Wordmeaning

(4) In consideration of thesefirst three points, the sorts of constraints needed to model the representation and acquisition of conceptscannot be based solely on either perceptual or grammatical bases; they must Also arise from blases given by specific patterns of explanation that emphasize different causal roles for the same properties in different domains. These conceptual constraints in turn suggest different views of possible constraints on the acquisition of word meaning.

The emergence of the concepts-in- theories view of concept structure

In the past three decades, models of categorization and concept structure have evolved through three stages. It is useful to briefly describe this history as a way of better understanding the current view. The first view tried to specify concept structure as lists of singly necessary and jointly sufficient features. Conceptssimply consistedof compartmentalized sets of features that were accessedas a cluster by a processing agent. Not surprisingly, this sort of representational theory of concepts was easy to model in a variety of computational systems. In addition , the first view fit nicely with some early feature-based models of word meaning, where again, each word consistedof a set of features that were singly necessaryand jointly sufficient (e.g. Leech 1974) . In psychology, these feature-list views survived far beyond their natural lives by focusing on laboratory learning of arbitrary ' ' ' ' concepts such as bliks being large blue triangles. Such learning tasks uncoveredsome strategiesused to encodearbitrary conjuncts and disjuncts of meaninglessattributes, but provided little insight into the acquisition and representation of natural concepts. The necessary and sufficient features model still has limited appeal becausesome word meaningsseemto logically entail others in a way that suggestsan underlying concept structure with necessityrelations; but several other models of concepts and word meanings can capture such entailments without embracing the idea of concepts being solely comprised in that manner (Chierchia and McConnell-Ginet 1990) . The first view yielded to a family of views collectively known as the probabilistic approach, in which concepts were said to reflect real world correlational structure and feature frequency (Rosch and Mervis 1975) . That approach spawned a huge body of studies arguing that concepts themselves are ill -defined probabilistic representations, consisting of weighted features, samplings of exemplars, or even combinations of dimensional values (Smith and Medin 1981) . Even as these studies collectively embraced probabilistic

F.C. Kei/ / Word meaning

accounts and were united in focusing on such phenomenaas instanceshaving different goodness of membership in a category, they began to diverge on what concepts actually were. Feature-based models" tended to be like the earlier necessaryand sufficient feature view except that they added weights to each feature representingits relative importance in detennining membership. Importance was usually derived from how often a feature co-occurred with members of the category in the real world . Correlations between features were also often included in these representations. One consequenceof these weightings was that a much larger number of features could be included in a representation and thresholds could be set up for excluding features with sufficientlylow weights. Thesethresholdscould also be adjustedas a function of contexts (as in Lakotrs hedges' technically speaking' and ' loosely thinking ' , which were thought to raise and lower the threshold respectively ( Lackoff 1972). Nonetheless, these views continued to compartmentalize concepts as distinct from ,the rest of knowledge. Certain phenomena related to typicality of instances were considered central to understanding conceptsand were shown to be strongly interrelated. These included: intuitions that membership in a category is not all or none but graded such that some instances are better members than others, intuitions that some entities were at the borderline and their membership in a category was indeterminate, and reaction times to identify instances(it takes longer to verify membership of an atypical vs. typical member). All of these responsesseemedto convergeon mental representationsthat encodedfeature frequenciesand correlations. This second view required more subtle refutations than the first. Concepts still seemed to have components that were different from their merely probabilistic parts; and demonstrations appeared showing that people could easily think about typical and atypical instances for completely well-defined categories, such as odd numbers. Such findings suggest that typicality and well-definednessare not mutually exclusive for the sameconcept (Arm strong et al. 1983). Indeed the probabilistic phenomena associated with concepts were sometimes relegated to the realm of ' identification procedures' for picking out instancesof concepts rather than to the concepts themselves. Additional concerns came from demonstrations of illusory correlations in the social and clinical psychology literature. That is, people will see nonexisting feature correlations when they follow from prior beliefs (Chapman and Chapman 1969) . Simple tabulations of feature frequenciesand co-occurrences in the world are not enough. In developmental research as well, conceptsemergedin ways not explainable by mere shiftings of either feature

F.C. Keitt Wordmeaning

frequencies or correlational weights. Thus, one set of studies show how developmental shifts in what are regarded as legitimate members of a kind , such as being a tiger or being an uncle, cannot be plausibly modeled by shifting probabilistic weights on features or changing global criteria of what frequenciesare to count as important (Keil 1989) . Other problems were seenin adult processingstudies in which two concepts with the same highly typical feature nonetheless placed greatly different emphasison those features becauseone played a much more central role in patterns of causal explanation. Thus, bananas and boomerangs were judged to be equally typically curved, but straight bananaswerejudged to be a much better new member of the class of bananas than straight boomerangs in the classof boomerangs(Medin and Shoben 1988) . This particular shapechange seemsto influence what it meansto be a boomerang to a much greater degree than a banana and does so in a way not predictable from feature frequencies or correlations. Problems of this sort with probabilistic models have led to what is known as the concepts-in -theories view (Murphy and Medin 1985) . A closer look at categorization, and increasingly at other phenomenathought to be related to concepts and their structure, has put a central emphasis on notions of explanation, mechanism and cause. People do not simply note feature frequencies and feature correlations ; they have strong intuitions about which frequencies and correlations are reasonable ones to link together in larger structures and which are not. Without theseintuitions , people would make no progressin learning and talking about common categoriesgiven the indefinitely large number of possible correlations and frequencies that can be tabulated from any natural scene. These intuitions seemmuch like intuitive theories of how things in a domain work and why they have the structure they do , hence the concepts-in -theories label. One on the most frustrating drawbacks of the current concepts-in -theories view is the lack of consensuson what theories really are and how they are mentally represented. Theories might be sets of propositions with causal connectivesinterspersedamong various logical connectives, all interconnected by deductive chains. Alternatively , theories might be more like mental models, with image-like notions of mechanism. Or , theories might not need any notions of cause whatsoever, just a more general senseof explanation; indeed some have decried the appearance of causal relations in any wellspecified theory (Hempel 1965, Russell 1924) . These controversies, however, should not blur a simple fact : some notion of explanatory coherence does have a powerful and overarching influence on almost any behavioral measure

F.C. Keill Word meaninR of concept structure. Above and beyond the details of representationalformat lies the common realization that our concepts for dogs, diners, and dandelions emphasizesome features and relations over others becauseof their fit within broader explanatory patterns.

3. Hybrid vigor

The increasedimportance of explanatory systemsin concept structure has suggesteda complementary need for uninterpreted probabilistic tabulations as part of concepts, resulting in a hybrid structure. For all but the most contrived cases, concepts may be intrinsic mixes of both systemsof explanation and atheoretic tabulations of properties. Any detailed account of the theories or explanatory systemsthat embed conceptswill end up confronting the same issue, regardlessof their particular approach. Such systemscannot fully interpret the raw data of experience, yet must rely on it . The limitations of explanatory systemsor theories in organizing properties and concept are best understood by a concrete example. Consider someone who has had a limited exposureto birds ; let us call him Icarus. Becauseof his limited experience, Icarus' s explanatory knowledge specific to birds is modest. In addition to knowing many general things about animals that apply to birds .as well, Icarus only knows explanatory reasons for properties corresponding to two sorts of bird category contrasts: flightless vs. flying birds and predators vs. prey. Thus, Icarus understandswhy flightless birds tend to have much smaller wings compared to body size than flying birds and why their legs tend to be bigger and more muscular; and he understandswhy predators have many properties that help them catch prey and why prey have many features that help them avoid predators. In this way explanatory knowledge helps order the conceptual space and helps influence intuitive inter -birds similarities, inductions about new properties, and categorization. Moreover, this knowledge helps constrain which correlations are first noted for novel instances. There is, however, a problem with birds that occupy the same spot in this two-dimensional spaceout which are easily distinguishable in terms of surface feature probabilities and correlations and which Icarus can in fact distinguish, such as a robin vs. a wren. They occupy the same place in Icarus' s explanatory matrix and yet Icarus stores additional information about them so as to be able to distinguish them. This information may well be largely associative and guided by broad hunches laid down by Icarus' s theory of animals and

F.C. Keill Wordmeaning

175

perhaps some general hunches about birds. Those hunches insure that even the associatively organized features will not include whether a bird was first seenon a tree with an odd vs. even number of branches, or whether it was facing left or right , or whether it was old or young. But , within those general constraints, many other regularities must indeed be stored purely in terms of correlations and frequencies. In this way, associative structures in concepts can persevere. This perseveranceis inevitable, simply becausewe can never have explanations for all regularities that we observe. It is tempting to try to exclude frequency and correlation information from the concept proper and say that they are only part of heuristics and identification procedures having to do with concept use; but such a move fails to explain why our beliefs are often directed specifically towards explaining those correlations; the correlations form an integral part of the system. Only in special caseswhere we have conventionally defined concepts with accidentally correlated features, such as the concept odd number, do the two aspectsbecomemore fully separable. There must be not only explanatory structures that narrow down an indefinitely large number of features and feature relations to a manageablenumber but also mechanismsfor storing information that is outside the ken of current explanation. We could never acquire new explanations if there were not some way of storing information external to current explanations. " These issueshave often led to proposals of a core- periphery distinction in concept structure, wherein typicality information is relegatedto the periphery (see discussions in Arm strong et al. 1983 and Rey 1983) . Although this distinction may imply that the periphery is less important , or even optional , the relation between the two facets of concepts may be more symbiotic. Explanations do not amount to much if they do not have anything to explain, and raw tabulations quickly overwhelm any informati ~n gathering system if it does not partially order that information in terms of explanatory usefulness. A parallel casecan be made for scientific theories. Scientific theories are sometimes presented as a set of tightly connected laws linked through deductive chains (e.g. Hempel and Oppenheim 1948), but in practice, they start with sets of regularities that they seek to explain, regularities that are noticed and remembered often before the fledgling theory has any way of incorporating them. The atheoretical component of concepts should therefore not be relegated to a ' periphery' that is not part of the concept proper . There is no general way to justify such a move despite those cases of a few formal and conventional terms where a clean distinction is possible. However, even as the

F. C. Keill Word meaning

atheoretical component must be part of the concept itself, it remains distinct. There is not an association-to- theory continuum consisting of increasingly strong and reliable correlations and frequencies. Such a continuum could not explain caseswhere high frequenciesand correlations are clearly understood as explanatorily irrelevant to membership in the category, whether it be hair length and gender or economic value and type of chemical element. Although explanatory systems may always need some reserves of correlational and frequency based information for interpretation, not all of the information in such reservesis always found meaningful, even when broad hunches suggest it might be.

4. Theorigi- of the hybrid The idea that most adult conceptshave a hybrid structure has not led to a consensuson how this relation comes about in development. Two sharply contrasting views predominate: ( 1) The earliest concepts are independent of theories and are therefore pure casesof the probabilistic models. The earliest concepts are constructed solely by tabulations of feature frequenciesand correlations presumably with the help of low -level, domain-general perceptual and cognitive blases. Early word meaningsat this time would be similarly basedon such tabulations. (2) Even the earliest conceptsmay be subject to organizational principles that go beyond tabulations of features. Primitive systems of explanation embed concepts even in infancy and certainly by the time of the first words ; or at least young children' s concept-related behaviors are only understandable by imputing to them mental structures like our own explanatory systems. This debate has proved difficult to resolve. Recent studies would seem to favor the explanations-from -the-start alternative as younger and younger children' s judgements are shown to apparently be governed by such explanations . Yet , advocates for the opposite view need merely claim that the acquisition of such explanatory systems occurs very early on in infancy (McClelland , forthcoming), a reply that becomesincreasingly difficult to test as ever younger infants are needed. But the tension between these views has resulted in an important empirical discovery. There has been a rapid downward march of the ages at which concepts are endowed with explanation, from five-year-olds postulated as purely associative beasts ( Vygotsky 1962,

F.C. Kei/ l Wordmeaning

Werner 1948, Quine 1977), to preschoolersbeing in such a state, and now to infants before their first words. Indeed, a strong casecan be made that four month-old infants categorize aspects of their physical and social worlds in ways only understandableby attributing to them domain specific systemsof causal explanation (e.g. Spelke et al. 1993, Leslie, in press) . The debate continues about even earlier origins (e.g. Slater 1993), but there is now little ' doubt that the child s first words must be sensitive to the same sorts of relations that have causeda dramatic shift in how adult conceptsare viewed. In my first attempts to understand how word meaningsmight changewith ' ' development, I posited a characteristic-to -defining shift in the acquisition of word meaning (Keil and Battennan 1984) . Following decades of vaguer claims about shifts from such things as holistic to analytic meanings, accidental to essentialfeatures and the like , one more testable possibility seemedthat early word meanings are very much like the probabilistic views of concepts, ' ' but then shifted to be more defining such that a simple principle characterized meaning. The predominant method was to present scenariosin which an instance had either all the characteristic features associatedwith a category but lacked critical defining ones or in which instances had all the critical defining features but had many highly uncharacteristic ones as well. Being an ~uncle' was asked either of friendly , gift giving , middle-aged men unrelated to ' one' s family or of brothers of one s parents who were still children and ' ' distinctly unfriendly . Being an island was asked of peninsulaswith beaches, palm trees and burled treasures or of cold , forbid ding beachless places ' surrounded by water on all sides. Children s judgements of instancesdid shift with age and on a domain by domain basis as shown in figure I (Kei I1989 ) ; but it becameincreasingly clear that a true characteristic-to -defining shift was not and could not be occurring. Even the youngest children were never simply tabulating up all salient feature frequenciesand correlations. No child thinks that uncles must have glasseseven if all the uncles they happen to have seen wear them. The features selectedby even the earliest word learners were always constrained by somenotions of reasonablenessfor the kind of thing in question. A second problem was that true definitions are rare occurrences in word meanings. Only a handful of words even approach clear simple definitions. Putnam ( 1975), estimated a few hundred in English, and even these are under contention (Lakoff 1987) . Thus, although the developmental changeis robust and easy to produce experimentally, it cannot really indicate a shift from one representational format to another. Rather, it appears to be two related phenomena: ( I ) There are increasing elaborations of explanatory systems

F.C. Kei/ I Wordmeaning

~ + d ",~-~-"+ . I C / u c / + d ~ /,-~-~-"-+ _ c / ~ + d ,K ~ ~ . . + c / ~ -..-".'~ c + / d ,:;.-< ' " ( ' + c / ~ K -

Moralterms

Mealterms

Tool terms

Kinshipterms

Cookingterms

-

-

-c/ +d

-to- definingshift in the acquisitionof word Fig. I . Illustration of an apparentcharacteristic . The y-axesrepresentthe extent to which eachdescribedentity wasjudged to be a meaning . Thex-axesrepresent threegradeschoolclasslevelsandadults. legitimatememberof thecategory The graphsshowthat thereis a developmental shift in whetherthe + characteristic / - defining + defining ones are taken to indicate membersof the descriptionsor the - characteristicl . In addition, the shifts occur at different times on a domain by domain basis. category .) (Adaptedfrom Keil 1989 with age such that explanations play ever more extensive roles in constraining what features and correlations are noticed . Thus , as explanation - based knowledge becomes more and more elaborated , default tabulations of information in associative terms are less common . ( 2) There are shifts in understanding which explanatory system is most relevant to a class of phenomena . A child might realize that ' uncle ' is better understood in terms of set of biological relations that comprise kinship and not in terms of social relations that govern

F. C. Keill Wordmeaning

friendship; the social explanation is discovered to generate more serious mistakes and is abandoned (Keil 1989, 1992) . A similar change of perspectivehas occurred with tenDS for natural kinds. For example, young children assert that zebras who are surgically transformed to look and act like horses are no longer zebras but truly horses. Older children declare the animal to still be a zebra, suggestingadevelop mental shift from a phenomenalsimilarity spaceto a theoretically driven one. After many follow -up studies conducted both by my research group and other groups, a different story emerges(Keil 1989) . Younger children may never be total phenomenalistshelplessly buffeted about by correlations and frequencies. There invariably seemsto be an understanding of deeper relations that allows them to go beyond what would reasonably be considered phenomenal similarity . Thus, even for three-year-olds, tigers can only be changed into lions if you use a mechanism of change that' is reasonably related to being a member of the two kinds. Younger children s beliefs about such mechanismsmay differ , but they have them nonethelessand will use them to override associativeinfonnation . At any age most natural concepts have a mix of associationistic tabulated information and systemsfor interpreting , explaining and guiding the pickup of that information . There can be dramatic developmental change, but not from one kind of representational system to a dramatically different one. Instead,- the predominant change is in how extensively the child is able to interpret and explain the raw data of association. As those explanations become more and more elaborated over time, the child has to fall back less and lesson the associativecomponent to make judgements. ' Following the Icarus example offered above, suppose a child s initial . understanding of birds involved only notions of what properties supported flight and thereby clusters of features corresponding to flightless vs. flying birds but did not understand how to organize the features that clustered around predator vs. prey. Some more general principles about animals may bias the child to associatively store frequenciesand correlations concerning featuressuch as feet shape, beak shape, eye location in head and typical diet ; but these properties may be stored largely in tenDS of associative relations until the predator/prey insight comes to dramatically organize those features and shift similarities accordingly, thereby shifting induction and categorization . Note that the developmental studies also support the essential hybrid structure of concepts. Even as these studies show that the youngest children never rely solely on brute force tabulations of feature frequencies and correlations, they also show that something like an associativecomponent is

F. C. Keil / Word meaning

also present that shrinks with age in each domain in the face of more elaborated explanation. Although the characteristic:-to -defining change in development is not strictly correct, the changesthat do occur support both aspectsof the hybrid .

S. Multiple domains andreferentiallyoverlappingambiguities The concepts-in-theories view suggestsmultiple modes of explanation from the start of acquisition of word meaning. At least two domains have been clearly implicated : (a) a physical-mechanical domain that helps explain the properties of kinds subject to mechanical causality; and (b) a folk -psychological domain that helps explain the properties of kinds subject to beliefdesire accounts of causation. These radically different ways of construing the . world result in sharply contrasting assumptions about what properties are central to membersof a kind . Carey ( 1985) was one of the first to make this proposal, and the evidence for early and universal appearanceof these two domains is now strong and ' widespread, ranging from infants clear intuitions about the mechanics of physical objects to findings that autistic children who have excellent intuitions about physical mechanics can be grossly deficient in their understanding of belief- desire causality. Severalstudies have now shown that high-functioning autistic children can reason about events that do not require belief- desire inferences, while having great difficulty reasoning about events that do require belief- desire inferences (e.g. Baron-Cohen et al. 1985) . One recent study suggeststhat the contrast between the two domains might already be under way in the first few months of life. Infants as young as six months have been shown to have markedly different expectations about the causal interactions among social entities as opposed to non-social ones. If they observe events in which a six foot high cylinder rolls towards another, they expect that only physical contact can produce a movement in a second one. If the first cylinder stops, leaving a gap between it and the second one, and the second one th~n moves off as if launched without contact, the infants (and adults) find the event anomalous. If , however, the same events occur with human actors, the infants find launching of the second person without contact to be no more surprising than launching with contact (Spelke et al. 1993) . If the young child initially has only these two fundamental modes of explanation, most concepts must be somehow assimilated into one of these

F.C. Keill Wordmeaning

two ways of understanding the world . This possibility results in predictions concerning not just the nature of early concepts but also how they become linked to the lexicon. If children are presentedwith partial information about a novel kind , they must.decide whether its known and future properties are to be interpreted in belief/ desire terms or in physical/ mechanical terms and ensuinginductions about properties will vary accordingly. For example, it has been argued that biological kinds and their properties are often interpreted in solely behavioral terms. The behavioral aspectsof a property come to be seen as the basis for it . Young children have been shown to attribute properties such as eating and having babies only to animals that are sufficiently psychologically similar to humans so as to have the behavioral and belief/ desirecorrelates of eating and having babies (e.g. feeling hungry and wanting ' food and being nurturant towards offspring) . Worms don t eat becausethey cannot have feelings of hunger and desires for food in any way like humans (Carey 1985). These sorts of misattributions were found not only forproper ties that have salient behaviors associatedwith them but also for unfamiliar ones described on the spot for the child (such as having a spleen) . Young children seemto assumethat even novel properties are likely to be possessed by other animals to the extent that they are behaviorally similar to the one on which they are taught. Only later in development would an appreciation of biological kinds as such emerge and would new properties be based on induction over sets of functional biological relations. It now seemsthat young children might not be so narrowly restricted in their earliest kinds of understanding, that the explanation part of the hybrid has more diversity than just a mechanics and psychology. For example, a wide range of studies now converge to suggest that preschoolers see living kinds as having their own causal patternings distinct from physical mechanics and social behavior (Keil 1992, Inagaki and Hatano 1993, Hatano et al. 1993, Springer and Keil 1991, Gelman and Gottfried 1993) . They understand that both plants and animals tend to have functional /adaptive explanations associated with them that are not seen elsewhere in the natural world and which are distinct from the sorts of functional explanations used with artifacts. For example, preschoolers show a stronger tendency to explain the properties of living things in terms of the purposes those properties serve for those things than they do for non-living things (Keil 1992). Adaptive , or design, explanations have becomerecognizedas a distinct form of explanation linked to the biological sciences , and it now appearsthat salient to young children available and is the same form of explanation (Woodfield 1976, Wright 1976) .

F.C. Keil / Word meaning

One way to show this distinctive pattern of expectationsconcerning living things is to ask preschoolers which of two explanations they prefer as appropriate for explaining the properties of living vs. non-living things. For ' example, the children might be told the following : Two people are talking about why plants are green. This person says it is becauseit is better for the plants to be green and it helps there to be more plants. This person says it is becausethere are little tiny parts in plants that when mixed together give them a green color. Which reason is a better one?' The same question would then be asked about emeralds. Although both the reductionist and functional explanations are appropriate for the plants, children preferred the functional sorts of explanations for living things while at the same time preferring the reductionist explanation for non-living things (Keil 1992). The contrast with artifacts is more subtle, but involves an understanding that most of the properties of non-domesticated living kinds are ultimately self-serving whereas most of the properties of artifacts are other -serving. This seemingly abstract notion appears to be well within the grasp of preschoolers when they are asked to choose between explanations for functional properties that are for the good of the object vs. the good of another entity ; and they show similar understandings for plants as well as animals, ruling out any need to see the living things as . capable of mental goals or desires. The full set of such early modes of construal may be quite small, possibly as few as half a dozen. The earliest modes of construal seemto originate from notions of broad domains of phenomena, such as physical mechanics, folk psychology, and functional /teleological explanations and not local areas of expertise such as dinosaurs or chess. Other possible basic modes include: moral reasoning, notions of ownership and transfer <;?f ownership, and social power relations. The existenceof other domains besidesmechanics, psychology , and design/teleology is speculative at this point , but remains plausible given the likely universal presenceof such domains and the possibility that they have distinctive fonDS of causal explanation. Alternatively , the basic three might h~ve a special status making them more fundamental than all other schemasfor making senseof the world . A major challenge for future work is to develop criteria that demonstrate how these basic modes of construal are distinct from the thousands of local explanations and mental models that people come to use in everyday tasks. In addition to different roles in processing, the basic modes may be earlier emerging and more invariant over the course of development.

F.C. Keill Word meaning

The early presenceof multiple forms of explanation may lead to a distinct kind of ambiguity for lexical items. The ambiguity arises from caseswhere heavily overlapping sets of individuals are meaningfully interpreted by different forms of explanation. For example, a class of people can often be understood in biological, social, or physical terms, just as properties of c.omputers can be understood .in mechanical, functional , or psychological terms. A computer might be described as failing a task becausetwo routines are seen as ' colliding ' (mechanical), becausethe programs are not designed for the task (functional ), or because the program cannot understand or remember the correct sequences(psychological) . Clearly distinct meanings can be invoked even though the real world referents may often be heavily overlapping. These examplesappear to be different from casesof vagueness or more standard lexical ambiguities where the referents are usually nonoverlapping ' ' ' ' , as with the two meanings of such terms as bat , bank , and ' tank ' . With standard lexical ambiguities, one gets the immediate impression switches meanings, whereaswith referentially as one of a new set of referents overlapping ambiguities, the meaning seemsto switch equally strongly but many of the same referents remain. Referentially overlapping ambiguities suggest an alternative account of many developmental changes in word meanings. Children might not be reworking the feature sets that organize members of a category and discarding the old (a pattern that has the counterintuitive consequenceof suggestingthat adults should have difficulty accessingearlier states of their own vocabularies) but rather realizing the relevance of a different, but already present, system of explanation for interpreting roughly the same properties. In the case of kinship terms, a preschooler might well have notions that there are ways of understanding things in social as well as in biological/ functional ways, but may have assumedearly on that instances of kinship terms were to be understood social/ behaviorally. A change in word meaning, to more classic bloodline relations might reflect not so much a new learning of biological relations, but an insight that a biological/ functional way of explaining properties and judging similarities is the most common one in adult usages of those terms. This speculation gains support from recent studies showing that , although younger children might have different default assumptions about properties for living things, modest contextual cues can result in biologically basedinductions. For example, when children judge that dogs and humans but not birds, snakes or insects eat, it appears as if they ' ' might have encoded eats as referring to social and belief/ desire aspectsof

F. C. KeU / Word meaning

eating. Yet the same child will also judge that eating applies to all and only animals if they are primed to think about terms like eating in biological/ functional terms ( Vera and Keil 1988) . Those studies are relevant because they illustrate how a property can alternately be embedded in two very different systems of explanation. Comparable switches in embedding for kinship terms could cause the sorts of referentially overlapping ambiguities proposed here. Apparent developmentalchangesin word meaning may therefore reflect an awarenessthat a different set of explanatory relations can be superimposed on roughly the same set of instances and properties so as to afford new insights. The different explanatory system may have been present for some time, but is now decided relevant to a class of lexical items in a certain domain. Shifts betweenmodes of explanation occur in adults as well. For example, most of the time we understand the personality traits and behaviors of others in terms of belief/ desire patterns of causation. John is afraid of snakes becausehe had some bad experienceswith them that led him to .believe that snakes are dangerous to him , even if those beliefs are false about most snakes. But we can understand the same traits in biological/ functional terms as well. One would then explain John' s fear of snakes not in terms of his beliefs and desires, but in terms of the ecological niches occupied by humans and their evolutionary predecessorsand of a need to develop an adaptation that causesa built -in fear of snakes. Although explanations of behaviors in biological/ functional terms as opposed to belief/ desire ones may not be the first option taken, once adopted, they lead to different inferences and understandings. If shifting modes of explanation over roughly the samereferents provides a senseof ambiguity, there should be other signs of that ambiguity as well. One example might be a tendency not to switch betweenmeaningswhen a word is shared in a clause. In the sentence' The pilot banked at the intersection of Pine and Locust and the lawyer at Oak and Walnut ' , it is bizarre to have ' bank' being used first as an airplane maneuver and second as fiscal action. ' ' Similarly, in the sentence The rock hit the house and John did too , it is ' awkward to have ' hit be in the mechanical/ billiard -ball sensefor the rock and in the intentional sensefor John. One is more inclined to seeJohn hitting the house in an inanimate senseas a hurtling body not intending the impact. " As a second example, consider the sentence The daffodil neededwater and ' ' ' John did too , where need has the senseof a physiological need in both cases, not as physiological need and explicit desire or wanting in the other. If

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185

this analysis is correct, a child hearing an unfamiliar tenD can safely assume that when a word is shared in usage, the mode of explanation is likely to remain constant. The awkwardness of mixing different sensesseemsless marked for other casesthat are not true ambiguities. For example, with metaphor, one can say ' ' ' ' Phil embraced her body, and Bill her ideas , where embrace clearly has different senses , but little awkwardness results. Similarly , with syncategore' ' matic terms like good , different sensescan be mixed in the sameclause, as in ' 'The meal was good and the fire was too . If thesesorts of intuitions prove to be more general, they suggestthat shifts in explanatory frameworks are not to be confused with a host of other possible context effects that cause more subtle shifts in meaning (Barsalou 1987, Lakoff 1987) . There are dozens of ' ' different nuancesof the word instrument depending on context, as there are ' of the verb ' cut ; but these do not seemto reflect deep shifts in explanatory frameworks.

6. Explanation - based constraints on concepts and word meanings

One possible consequenceof the concepts-in -theories view in concert with multiple early domains and shifting modes of construal is that causal explanatory blasesmight constrain inferencesabout early word meanings in ways that have sometimesbeen assumedto be more in the province of perceptual blases. Thus, several researchershave suggestedthat young children might ' have a ' shape bias in terms of how they approach the meanings of novel nouns, especiallywhen used as count nouns (seeLandau, this volume) . Such a bias might well exist, but its origins may not be simply in the form of a perceptual rule, but rather in terms of what sorts of properties are more central to understanding different sorts of kinds. Fundamental modes of explanation might influence the shapebias from the earliest times of lexical acquisition. Thinking of something simply as a physical object and in terms of its overall paths of motion should actually reduce the shapebias, whereasthinking of it as a biological functional thing, or an artifactual functional thing should have a stronger impact on the shape bias. Thus, the simplest naive physics envisions objects as point massesand predicts their trajectories accordingly with little regard for their shape. Heavy things push lighter things further than the opposite, and objects that hit another head-on have more of an effect than those that just graze them at an angle. A functional approach to objects, however, pays close attention to

F.C. Kei/ I Word meaning

aspectsof shape in making inferencesabout function. Moreover, shape itself might be more profit ably subdivided into overall shape vs. local parts and relative spatial arrangements, with one aspect more important for artifacts and the other for living kinds. There might not be any general shapebias, but rather an understanding of the different degrees of importance of certain aspectsof shapein different explanatory systems. Shape, or more properly its subtypes, might then be seen as one of several sorts of properties whose centrality can vary as a function of the kind of entities considered (seealso Bloom, this volume) . This alternative would gain support if the bias varied in strength as a consequenceof the type of explanatory system invoked by an object or category. Some evidence is already present in cases where adding eyes to inanimate objects changesthe strength of the shape bias at different ages in different ways (e.g. eyes make an uninterpretable object for a younger child becomea living kind for which shape matters a great deal ... whereasmore complex interactions with texture and color are invoked in older children (Landau, this volume . We have begun exploring this issue with both adults and children. With adults, the experimental paradigm involves describing a change in types of properties of typical members of familiar categories and asking about the effectsof such changeson the categorical and lexical status of those members. Four- changesin property types were used: color , size, shape(as specifiedby a tripling of width and a one-third reduction of height), and surface pattern. Thesechangeswere described for randomly selectedmembersof four categories : animals, plants, non-living natural kinds (e.g. rocks), and artifacts. Subjectswere given instancesof a member of a category and asked about the effects of changesof different feature types. For example, subjects might be told about some artifacts that are exactly like ordinary chairs in every way except that all members of this group are normally uniformly shaded bright pink . The subjects would then be asked if it would still be called a chair. A different item might ask about rocks that were just like gold except that they are nonnally bright pink . One group of subjects were asked whether the object with the altered feature should be assigned the standard name, one group was asked how well the altered object would function in the original role, and a third group was asked how unusual a member of the original category the altered member would be. With the exception of functional intuitions about non-living natural kinds, adults have reliable intuitions about such questions and show clear patterns of responses . Functional questions were asked of things like kinds or rocks to keep the design consistent across

F.C. Kei/ I Wordmeaning

all categoriesand to check that in fact they would be lessinfonnative for such kinds. The importance of property types varies strongly as a function of the kind of thing querled. Overall shape and size changeshad a profound impact on functional roles of artifacts as well as on their lexical labels. By contrast changes in color and surface patternings were irrelevant for comparable ratings of artifacts. For non-living natural kinds, such as minerals, the effects were roughly reversed, with color and patterning being seenas essentialto the judgements and shape and size as largely irrelevant. For both plants and animals the results were consistently similar , suggestinga set of expectations about the category of living things in general. Shapeand color were generally seenas most relevant across conditions and size as least relevant, a pattern that was clearly distinct from both artifacts and non-living natural kinds. An example of these different patterns of judgement for naming is shown in figure 2. Above and beyond the differences just described for the data set as a whole, judgements also varied as a function of the kind of question asked. Questionsabout what the altered entity should be called had different profiles across the three category types than did questions about its function or unusualness . This finding illustrates that judgements about preservation of function and typicality are not the sameasjudgements of what a thing should be called.- Such differencesmight seemobvious, but they are often conftated in experimental researchwhere results collected with one type of judgement are compared to those collected with another. Moreover, as seenshortly , the precise nature of their interactions can be informative about the roles of specific properties in particular categories. One final measurement taken in these studies provided an important finding . After all initial ratings were completed, subjects were asked to consider ordinary exemplars of each of the judged categories and rate how much those items normally vary with respect to overall shape, size color , of patterning. Thus, a subject might be asked to judge how much ordinary chairs, or lumps of gold, vary in color. These questions were designed to addressan important issuein the literature : how much the natural variability of features in a category could cause the discounting or emphasis of the importance of featureswhen querled in one of the three ways. A 3-inch disk is more likely to be considered a pizza than a quarter, even though it is more similar to the quarter in physical size, because the minimal variability of currency disallows even modest size changeswhereasthe larger variability of size for pizzas allows for an albeit implausible 3-inch pizza (Rips 1989).

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Perhaps more generally, tabulations of variability are the basis for judgements of the effectsof changing properties: the lower the variability , the more the judged impact of the change. In thesestudies, variability alone did not predict the significant effectsseen for any of the three judgement types. For example, if a subject said that color typically varied more for chairs than for whales, those judgements did not predict other judgements about category membership when the color was changedfor novel instances. However, when the data analysis was performed

F.C. Kei/ I Word meaning

in a rnanner that looked for patterns remaining after all contributions by variability were nurnerically removed, there were differencesacrossjudgement types. For judgernents of function , high variability of a feature had little influence predicting the effect$ of changing that feature. Consequently, when variability was factored out , the differences in property effects across categories were still large and robust. Even when an item' s color or shapevaries greatly in the real world , variability is largely ignored in making judgments about functional influences; instead the deviant instanceitself is examined for . By contrast, judgements about the appropriate specific functional consequences narne were influenced by variability not by allowing predictions of effects, but by eliminating differences in property effects across categories. Thus, although neither variability judgements alone, nor property -type cornbinations alone, could predict judgement of naming, their joint action produced reliable effects. In a related pattern, variability mattered more for non-living natural kinds, for which function is irrelevant, than for artifacts. In surn, in no casesare intuitions about property variability for instances adequate to predict how changes in those properties influence categoryrelated judgrnents about those instances; but in the case of naming judgernents, property variability is involved in interaction with other factors. The assignment of labels may therefore rely more on the heterogeneous aspectsof concepts than other category-related judgements since both variability information for instances and general views about differences in property importance across broad category types are involved. Variability may be information stored largely through associative means, whereas the differential effectsof property types as a function of category seemlinked to the natural explanatory systemsinvoked by such kinds as living things, artifacts, and sentient beings. Any number of simple frequency and correlation tabulation systemscan note how often features vary for instancesin a category and accessthis information through network in which activation strength is a function of those tabulations, hence the notion that associative means of representation would be adequate. By contrast, judgements about which properties are most central to a category and causethe most disruption when negatedseemto arise from notions about the causal structures underlying the property configurations of broad categoriesand how particular properties are much more closely connected to those causal structures than others. Such judgementscannot be captured by storing information about feature frequencies acrossinstancesas they rely on beliefs about mechanismand explanation. Thus, arguments made in earlier sectionsof this paper about the importance of hybrid structure may emerge with a vengeancein the case of mapping

F.C. Kei/ l Wordmeaning

concepts into the lexicon. (For other arguments about the special influences of lexical items seeMarkman 1989and Woodward 1992.) It is one thing to demonstrate that adults seemto be strongly influenced by abstract explanatory belief systemsin how they interpret the importance of properties for different categoriesof things. It is quite another to demonstrate that such systems might be implicated early in life when the lexicon is growing most rapidly . We have begun a seriesof studies addressingthis issue as well. These studies use triads of pictures in which an exemplar with a novel name is shown followed by an object that varies in the shapesof the most salient parts but which preservescolor and surface patterning and by another object that preservesall shapesbut varies in colors and surface patterning. In each case, novel items and names are clearly depicted as being from one of four categories: artifact , plant , animal, or non-living natural kind . The original object is referred to in a manner that is indeterminate betweencount ' ' and mass(e.g. ' this is an animal that is in the hyrax group and this is a rock ' ' ' that is of the malachite group or this is my hyrax ... it is a kind of animal ' ' and This is my malachite ... it is a kind of rock ) . In one preliminary study 16 three- and four -year-olds ignored shape and emphasizedcolor when deciding which of two novel non-living natural kinds shared the same label as an originally labeled one. For the living kinds and the artifacts, shape differencesas depicted by different parts are vastly more important . Color and texture also playa role for living things but not at all for artifacts where, with few exceptions, they may apparently be understood as purely conventional. This insight may get stronger as the children get older and enter elementary school, a pattern that is now under active study. One aspectof the results is shown in figure 3. A secondstudy now under way suggeststhat shapechangesnot implicating changes in salient parts are seen as less important for living kinds than artifacts because of their generally smaller roles in changing functional properties for living things. Different parts compel a senseof category change for li .ying things. We have constructed stimuli sets where a class of novel . things is distorted two ways: ( I ) a computer graphics transformation displaces the image pixels such that the object becomestwisted around its central point and thus the overall shape is dramatically changed whereaslocal parts stay pretty much the sameand in roughly the samerelations to each other ; or (2) the overall shape is not changed, but small properties are substituted for other ones, such as one kind of beak for another on a bird , or one kind of a dial for another on a machine. When preschoolers are shown these images

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and told that a target image has a certain .novel label and are then asked which of the other two images (the overall shape distortion vs. local parts substitution) should also take the same label, they give different patterns of responsesfor living kinds vs. artifacts. For plants and animals, local part differences from the target are much more important than overall shape differenceswhereasthe opposite is true for the artifacts, as long as the local part changesare not seenas disrupting function . These sorts of expectations could certainly constrain how they learn the meanings of new words. Follow -up studies have used ambiguous displays where the triads are labeled in one caseas a kind of animal, and in other casesas a kind of nonliving natural kind or a machine. In these cases, with precisely the same display, generalizationsare different depending on how the depicted entity is construed. Preliminary studies with preschoolers suggest that when, for example, an entity is labeled a frog , the shapechangeis critical ; but when it is labeled a rock , color and texture becomescritical ; hence expectations of the kind of things observed can guide how properties and similarities are interpreted for exactly the samedisplays. The examples offered here raise the possibility that many constraints on early concept learning and on word learning may flow from our beliefs about the sorts of properties and relations most explanatorily central to fundamental kinds of things. Shape, like any other property , may betheory dependent for its perceived causal powers and central organizing role in a category. Very young children seemto have setsof strong expectationsabout

192

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the likely causal power of different properties in organizing categories at a high level of abstraction (e.g. living thing and artifact ) . However, expectations are less influential for individual items, arguing against some simple storage of concrete exemplarsand comparison back to those instances. Perhapsthese effect do not operate at finer levels of categorization. Strong effects of different causal centrality for properties may exist at levels such as living kinds, substancesand artifacts, but not at much finer levels such as birds vs. fish. That is, it may be difficult to find properties applicable to both fish and birds which, when counterfactualized, distinguish among them by having a strong effect in one caseand not in another. Note that the properties cannot be one like ' breathes underwater' since it is already counterfactual for birds. Of course, many properties are causally central to both , but the kinds of properties that are causally most potent may be pretty much the sameacross all animals and reflect general notions about the sorts of causal patterns distinctive to living things.

7. Conclusions I have argued for the following themes: Current views of conceptsrequire that they be acquired and representedin terms of a systemthat has two distinct components: one that stores frequency and correlation information through domain-general procedures, and one that carries domain-specific beliefs about causal relations that help explain property relations. This hybrid structure is well supported by a wide range of experimental studies as well as more principled considerations. The beliefs about causal patternings and property types are linked to broad domains of explanation, such as sentient beings, living kinds and artifacts. Those domains seem different from the many smaller domains of expertise that all of us come to acquire as well. The evidencehere is still accumulating but indications come from distinct sources, such as beliefs about how property changesinfluence category integrity and how ways of understanding classesof things seemto shift in development and acrossdifferent contexts. This hybrid mixture appears to be present throughout much of cognitive development, at least by the time first words are acquired and quite possibly much earlier. The evidence here arises from the failure of domain-general tabulation models on their own to explain young children' s performance on a wide variety of tasks involving concepts. There is less evidencefor just how many of these basic domains might exist in the prelinguistic child. I have

F.C. Kei/ I Wordmeaning

argued that there are good reasons to suspectat least three and speculated that as many as half a dozen more seemplausible. These patterns concerning the acquisition and representation of concepts matter directly for models of lexical representationand acquisition. Both the strategiesused to acquire word meaningsand their underlying representations themselvesare deeply affected by such views about concepts. The hybrid structure suggeststhat word meanings are linked both to frequency-based information and to causal/ explanatory beliefs and that different sorts of lexical tasks may highlight one or the other of these two facets. Empirical studies of the lexicon must therefore keep in mind these two facets and their interactions with specific tasks. Becausethe hybrid structure appears to be already present in the prelinguistic child , both facets influence the child ' s first attempts to learn the meanings of words, hence the claim that there are explanation-based constraints on the acquisition of word meaning. If early representations were only based on tabulations of feature frequencies, then strategiesthat key on some of these features, such as shape, might be the sole means of narrowing down the hypothesis space of what novel words refer to. Instead, even the first guessesabout word meanings may be biased not only by bottom -up counts of feature frequenciesand correlations, but also by top- down abstract expectationsabout what sorts of featureswill be causally central to a domain. Apparent developmental shifts in the internal representations of word meaningsrarely, if ever, are signs of a change in basic underlying representational format . Instead they may representincreasing elaboration of explanatory beliefs that are able to interpret a larger and larger percent of the tabulated information and shifts in which explanatory systemis deemedmost relevant to understanding membersof a category. Younger children may not be showing an inability to represent word meanings in certain formats as much as they are exercisingdifferent default options and having lessdetail in some of their explanatory systems. The hybrid structure and its early appearancehighlights a different kind of ambiguity in word meaning, wherein largely overlapping sets of instances may have the same label applied to them but have different meanings, with different inductions, different categorizations of critical test cases, and a clear senseof ambiguity as opposed to vaguenessor synonymy. It appearsthat the shifts of meaning here are not caused by realizing that a label points to a ' wholly different part of one s conceptual system with different instancesand feature clusters, but rather by realizing that the label may point to a class of things that can be interpreted in terms of more than one explanatory schema.

F.C. Keill Wordmeaning

Seeingconceptsas essentialhybrids of explanation and association has led to the claim that early word learners have explanatory blasesthat guide first guessesabout the sorts of properties that are most strongly causally linked to the central structure of a category. These blasesappear to be high level and abstract yet also powerful in how they guide choices of relevant properties. The acquisition of word meaning is thus suggestednot to rise out of higher and higher order tabulations of regularities among perceptual primitives, but from the start to be strongly influenced by overarching distinct patterns of explanation that are associated with such domains as biological kinds, artifacts, and sentient beings. In addition , the possibility of a handful of such patterns early on allows for much of semantic development to involve switching among these patterns and not acquisition of totally new forms of explanation. These discussionshave carefully skirted questions of what explanations or theories are really like ; but one possibility is that they are not much at all like theories in the classic nomological-deductive sense. Increasingly in the philo sophy of science, it is common to attribute to the working scientist not a set of propositions linked by rules of inference, but something less structured involving notions of causal powers (Salmon 198?) . Not only children, but also adults, often have explanations in the form of notions about the sorts of properties likely to be causally most central to a kind , with only the vaguest of hunchesabout how they are linked together. It may therefore be that the earliest notions of what properties are central to a category are not so much consequencesof a deepertheory, but are much of the theory itself. Lexical items cannot be simply equated with concepts; but neith,er can they ignore the details of concept structure. In this paper I have -argued that a current view of conceptsand concept acquisition has important consequences for how we might think of word meanings and how they are acquired. The notion of hybrid structure, its early origins, the presenceof multiple early modesof construal, and subsequentconstraints suggesta very different model of how lexical items becomemapped onto conceptsand changewith development than would be suggestedby alternative models of concepts. Even if one is solely interested in the lexicon, one cannot avoid making some commitments about concepts themselves. References . Whatsomeconceptsmightnot be. Cognition ArmstrongS.. L. GleitmanandH. Gleitman. 1983 13. 263- 308.

F. C. Keitt Word meaning Baron-Cohen, S., A .M . Leslie and U . Frith , 1985. Does the autistic child have a ' theory of ' mind ? Cognition 21, 37- 46. Barsalou, L . W., 1987. The instability of graded structure: Implications for the nature of concepts. In : U . Neisser (ed.) Concepts and conceptual development: Ecological and intellectual factors in categorization, 101- 140. Cambridge: Cambridge University Press. Bloom, P., 1994. Possible names: The role of syntax-semanticsmappings in the acquisition of

nominals . Lingua92, 297- 329(this volume). . Conceptualchangein childhood. Cambridge S. 1985 . , MA : MIT Press Carey, , L. J. and J.P. 1969 . correlation as an obstacle to the useof valid , , Chapman Chapman Illusory 74, 272- 280. psychodiagnostic signs. Journalof AbnonnalPsychology . The roleof coherence in differentiatinggenuinefrom spurious Cheng,P.W. and Y. Lien, in press causes . In: D. Sperber acrosscultureand development , A. Premack(eds.), Causalunderstandings . Cambridge : CambridgeUniversityPress . -Ginet, 1990 Chierchia . Meaningand grammar: An introduction to , G. and S. McConnell semantics . Cambridge . , MA : MIT Press . The child' s theoryof living things. Presentation Gelman, S. and G. Gottfried, 1993 at the 1993 of the for Research in Child Development . , NewOrleans Meeting Society Hatano, G., R.S. Siegier . Thedevelopment of biological , K. Inagaki, R. Stavyand N. Wax, 1993 : A multinational study. CognitiveDevelopment 8, 47- 62. knowledge . Aspectsof scientificexplanationand other essaysin the philosophyof , C.G., 1965 Hempel . New York: FreePress . science . Studiesin thelogicof explanation . Philosophyof Science , C.G. andP. Oppenheim , 1948 Hempel 15, 135- 175. . Youngchildren's understanding of the mind- bodydistinction. Inagaki, K. andG. Hatano, 1993 Child Development (in press ). . The acquisitionof natural kind and artifact tenDs. In: W. Demopoulos Keil, F.C., 1986 , A. Marras(eds.), Languagelearningand conceptacquisition , 133- 153. Norwood, NJ: Ablex. . Concepts Keil, F.C., 1989 . Cambridge , kindsandcognitivedevelopment , MA : BradfordBooks. . The originsof an autonomousbiology. In: M. A. Gunnar, M. Maratsos(eds.), Keil, F.C., 1992 The MinnesotaSymposium on Child Psychology , Vol. 25: 103- 137. Hillsdale, NJ: Erlbaum. -to-definingshift in the development . A characteristic Keil, F.C. and N. Battennan, 1984 of word . Journal of Verbal and Verbal Behavior , 23, 221- 236. meaning Learning . Hedges : A studyin meaningcriteriaandthe logicof fuzzyconcepts . Journalof Lakoff, G., 1972 PhilosophicalLogic 2, 458- 508. . Women, fire, and dangerousthings: What categoriesrevealabout the mind. Lakoff, G., 1987 . , IL : Universityof ChicagoPress Chicago Landau, B., 1994 . Where's what and what's where: The languageof objectsin space . Lingua92, 259- 296(this volume). Leech . Semantics . Hannondsworth . , G., 1974 , England: Penguin Leslie, A., in press . TOBY and TOM. In: D. Sperber , A. Premack(eds.), Causalunderstandings acrosscultureand development . Cambridge : CambridgeUniversityPress . Markman, E., 1989 . Categorization and namingin children: Problemsof induction. Cambridge , . MA : BradfordBooks/MIT Press . Paralleldistributedprocessing : Implicationsfor cognitivedevelopment . Mclelland, J., forthcoming . Contextandstructurein conceptual combination . Cognitive Medin, D. L. and E.J. Shoben , 1988 20, 158- 190. Psychology

F. C. Keil / Word meaning

. The role of theoriesin conceptualcoherence . Psychological Murphy, G.L. and D. Medin, 1985 Review92, 289- 316. . The meaningof meaning . In: H. Putnam(ed.), Mind, languageand reality, Putnam, H., 1975 . 215- 271. London: CambridgeUniversityPress . Natural kinds. In: S.P. Schwartz(ed.), Naming, necessity , and natural Quine, W.V.O., 1977 . kinds, 155- 175. Ithaca, NY : CornellUniversityPress . Cognition15, 237- 262. . Conceptsand stereotypes Rey, G., 1983 . In: S. Vosnaidu . Similarity, typicality, and categorization , A. Ortony (eds.), Rips, L.J., 1989 . , 21- 59. New York: CambridgeUniversityPress Similarityand analogicalreasoning : Studiesin the internal structureof . Family resemblances Rosch, E. and C.B. Mervis, 1975 7, 573- 605. . CognitivePsychology categories Russell . Logicalatomism. In : J.H. Muirhead(ed.), ContemporaryBritish philosophy , , B., 1924 1stseries , 357- 383. London: Allen and Unwin. . Minneapolis . Four decadesof scientificexplanation Salmon , MN : Universityof , W.C., 1989 . MinnesotaPress at the 1993Meeting . Commentson symposiumon infant cognition. Presentation Slater, A., 1993 . in Child Development of the Society , New Orleans . for Research . Cambridge . Categorizationand concepts Smith, E.E. and Medin, D.L., 1981 , MA : Harvard . UniversityPress . Kind of objectsand causalrelationsin infancy , E., A. Woodwardand A. Phillips, 1993 Spelke acrosscultureand , A. Premack(eds.), Causalunderstandings (tentativetitle). In: D. Sperber . : CambridgeUniversityPress . Cambridge development . Early differentiationof causalmechanisms , K. and F.C. Keil, 1991 appropriateto Springer 62, 767- 781. biologicaland nonbiologicalkinds. Child Development . The development of inductionsabout biologicalkinds. Presentation Vera, A. and F.C. Keil, 1988 . at the Annual Meetingof the Psychonomic , Chicago , IL. Society . Thoughtandlanguage(E. Hartmann, G. Vakar, TransCambridge, MA : Vygotsky, L.S., 1962 . MIT press . Comparativepsychologyof mentaldevelopment Werner, H., 1948 (2nd edition). New York: . InternationalUniversitiesPress . : CambridgeUniversityPress . Teleology . Cambridge Woodfield, A., 1976 . The role of the whole objectassumptionin early word learning. PhiD. Woodward , A., 1992 dissertation , StanfordUniversity. : An etiologicalanalysisof goals and functions. . Teleologicalexplanations Wright, L., 1976 . , CA: Universityof CaliforniaPress Berkeley

Section 4

Categories , words , and language

) 199-227. North-Holland Lingua92 ( 1994

Constraints on word meaning in * early language acquisition Ellen M . Markman , USA , Stanford, CA 94305 , StanfordUniversity of Psychology Department fully acquire the vocabulary of their native languagedespite their Very young children success ' limited information processing abilities. One partial explanation for children s successat the inductive problem word learning presents is that children are constrained in the kinds of hypotheses they consider as potential meanings of novel words. Three such constraints are discussed: ( I ) the whole-object assumptionwhich leadschildren to infer that terms refer to objects as a whole rather than to their parts, substance, color , or other properties; (2) the taxonomic assumptionwhich leads children to extend words to objects or entities of like kind ; and (3) the mutual exclusivity assumptionwhich leadschildren to avoid two labels for the sameobject. Recent evidenceis reviewedsuggestingthat all three constraints are available to babiesby the time of the naming explosion. Given the importance of word learning, children might be expectedto recruit ' whatever sources of information they can to narrow down a word s meaning, including information provided by grammatical form class and the pragmatics of the situation. Word learning cOnstraintsinteract with theseother sourcesof information but are also argued to be an especiallyuseful source of infonnation for children who have not yet masteredgrammatical form class in that constraints should function as an entering wedge into languageacquisition.

1. Introduction

One impressive accomplishment of young children is the degree to which they acquire the vocabulary of their native language. Not only is the rate and ' extent of young children s word learning impressive, it is puzzling as well. ' Given the limitations on children s hypothesis testing, reasoning, memory, and other information processingabilities, their facility for building a lexicon is evenmore striking . This is especiallyso in light of the well-known inductive problem that word learning poses(Quine 1960) . Faced with an infinite set of

.

This work was supported in part by NSF Grant # BNS-9109236. I am very grateful to Andrea Backscheiderfor allowing me to publish the results of our study here. I thank Barbara Landau, Lila Gleitman, and two anonymous reviewersfor their helpful comments.

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possibilities about what a novel word might mean, the speed with which young children acquire word meanings requires explanation. Given the importance of word learning for language acquisition, children might be expected to recruit whatever sources of information they can to narrow down a word ' s meaning. One powerful one, for children old enough to benefit from it , is grammatical form class. As one example, Fisher et ale (this volume) provides dramatic demonstrations of the way in which syntactic information helps constrain the meaning of a novel verb (seealso Fisher et ale 1991, Naigles et ale 1992) . Being able to infer aspectsof the communicative intent of a speaker should provide another source of information about the referent of a novel term. A conscientiousparent or other tutor might further help by arranging the environment in ways to exaggeratethe salienceof the aspect of the situation being labeled in the hope that their child will find it salient too. ,Another potentially powerful source of information young children can use to figure out the meaning of a new word comes from wordlearning constraints. Constraints on word meaning may be particularly critical for babies who have not yet learned enough syntax to rely on ' grammatical form class to limit their hypothesesas to a word s meaning. I will argue that by the time they are ready to acquire vocabulary, children place constraints on possible word meanings, thereby greatly reducing the hypothesis space that needs to be considered. Children would not need to formulate a long list of potential meanings and painstakingly assessthe evidence in support of each. Rather, they could quickly zoom in on some hypothesesthat they are predisposedto prefer. In this paper, I will consider evidence in support of three word -learning constraints: the whole-object, taxonomic, and mutual exclusivity assumptions . I will argue that the most recent evidence supports the claim that children' s early word learning is guided by such constraints. For some different formulations of possible constraints seeBloom (this volume) ; Clark 1991; Golinkoff et al. 1992a). To claim that children' s early word learning is a constrained form of learning is nqt to claim that no other source of information matters. On the contrary, the recent evidence reveals some of the complex and subtle ways that word learning blasesinteract with other sour~ s of information . There is evidence, for example, that word -learning constraints can affect each other. When two or more constraints converge on the same hypothesis the learning will be efficient compared to cases where the constraints conflict and one must override another. Similarly word -learning constraints interact with grammatical form class. In some casesboth thesesourcesof information lead

E.M. MarkmanI Early language acquisition

to the sameconclusion about a novel word , but in other casesthey conflict. Analogous points can be made about communicative or pragmatic sourcesof information and the word learning assumptions. Finally , there is emerging evidence about the ways that the processing demands of a given word learning situation can affect the use of constraints. The evidenceI will review suggeststhat beginning word-learners rely heavily on word -learning assumptions but that these constraints are modulated by other constraints, by ' nonlinguistic context, by children s problem solving and other information processing abilities, and by the pragmatics and syntax of the language children hear.

2. Some preliminary considerado . .

In this paper, I will reviewstudiestestingthe hypothesisthat word-learning constraintsprovide young - children with an essentialsourceof infonnation about the meaning of a novel word. That is, that such constraints provide a partial explanation for the speedwith which new words are acquired. Before turning to the evidence, I will briefly consider a few theoretical issuesin order to sharpen the fonnulation of the hypothesis. 2.1. The developmental hypothesis

One way of fonnulating this hypothesis is to expect word -learning constraints to be available at the start of language acquisition. This would require documenting that at least some constraints are used by babies by the time they are capable even of understanding their first word . Babies acquire their first word often by age one year or less if measuredby production and probably younger if measuredby comprehension. There is reason to believe, however, that the nature of word learning undergoesa marked developmental shift from the time babies are capable of acquiring their first word at say a year and the rapid word learning they becomecapable of by 18 months or 2 years (Bloom et al. 1985, Corrigan 1983, Dromi 1987, Halliday 1975, McShane 1979, Nelson 1973) . The contrast betweenvery early word learning and this vocabulary spurt or naming explosion has been characterized in a number of different ways. The early phase of word learning has been tenDed ' ' prelexical (Nelson and Lucariello 1985) to emphasizethat there are ways in ' which the first ' words' may not be word like ; it has been called nonreferen' ' ' tial (Snyder et al. 1981) and associative (Lock 1980) to distinguish these

E.M . Markman / Early languageacquisition

' ' early words from genuine words that are referential; and it has been termed ' formative' per (Snyder et al. 1981) to suggest that the early words are used to perform some instrumental act rather than functioning as responses words that make reference. Another characteristic of this first phase of word learning is that words are added to the productive lexicon very slowly. A slow accumulation of new words might proceed by some relatively unconstrained associativemechanism. Dozens or even hundreds of trials may be neededfor a baby to learn, for example, to say ' bye-bye' on command. This is in marked contrast to the very fast acquisition seenaround 18 months. This developmental shift at the time of the naming explosion suggestsan alternative formulation of the hypothesis that word -learning constraints are necessaryfor word learning. The more preciseclaim is that some constrained form of learning is necessaryto account for the rapid acquisition of words seen at the time of the naming explosion. Babies could not be acquiring words at the rate of 30 or so a week if they were open-mindedly considering all possible hypotheseseach time they encountered a novel word. Thus the main hypothesis to be evaluated here is that word -learning constraints are available to babies by the time they enter the naming explosion at roughly 18 months of age. 2.2. Word-learning constraintsas default assumptions Before summarizing the evidencethat the word learning of 1Y2-year-olds is a constrained form of learning, I would like to clarify the claim. Some confusion has been generated by the terminology where ' constraints' is interpreted differently by different disciplines, especially linguistics versus ethology. I and other investigators have borrowed the terminology from the ethology of learning (seeWoodward and Markman 1991 for a discussion of this perspective). Within this discipline ' constraints' on learning are formulated as default assumptions - probabilistic blases that provide good first guessesas to a problem an organism must solve (Marler and Terrace 1984, Rozin and Schull 1988, Shettleworth 1984). To take one example from Gould and Marler ( 1984), foraging beesmust learn the color of the flowers that yield a given nectar. Purple is the default value beeshold. It is easier for them to learn about purple flowers than about flowers of any other color. Note that it is by no means impossible for them to learn sources that are other colors. Violations of the default assumption are common. Nevertheless, purple serves as a first guess, and it takes more trials or more evidenceto learn values that differ from the default assumption. Turning to word learning, the hypothesis

, acquisition E.M. MarkmanI Early language

203

is that children are able to make progress in word learning by use of such default assumptions (see Merriman and Bowman 1989 and Woodward and Markman 1991) . These constraints on learning provide good first guesses about the likely meanings of terms. Words that conform to the constraints should therefore be easier to learn than ones that violate them. Some of the controversy surrounding such claims stems from confusion over whether constraints must be absolute or whether they function as default assumptions (Gathercole 1989, Nelson 1988, Tomasello 1992) . 2.3. Are word - learning constraints domain -specific ?

To clarify another potential source of confusion, I ' d like to briefly consider the question of whether the word learning constraints I will consider here- the whole-object, taxonomic and mutual exclusivity assumptions- are specific to languageor available to other domains. Rather than discussthis here, let me refer you to Markman ( 1992), where this issue is considered in detail along with speculationsabout the origins of the constraints. My conclusion is that there is no reasonat all to believe that thesethree constraints are limited only to word learning and good reason to think they are available to some other domains. This is not to say that they are domain-general in that important domains are organized by very different principles. Given that analogous constraints are available to some fundamental domains, I suggestedthat word-learning constraints have been recruited from existing abilities that children possessrather than evolving as special purpose mechanismsonly for word learning (Markman 1992). Such speculations aside, these assumptions function as word -learning constraints, not in the sensethat they are domainspecific, but in the sensethat they help solve the inductive problem that word learning poses.

3. The taxonomic assumption

The first assumption I will consider is the taxonomic assumption which statesthat terms refer to entities of the samekind . An object term would refer to objects of the samekind , a color term to colors of the samekind , an action term to actions of the same kind , and so on. Although to adults this might seemself-evident, there was reasonto question whether young children would interpret terms in this way. First , taxonomic relations are not the only relations available to children. A label learned for a given object, for example,

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could refer to objects of the same kind , but it could in principle refer to the object and its spatial location , or the object and its owner, or the object and a salient part , etc. This is not , moreover, just a theoretical possibility . Many studies of classification have found that not only do children attend to such ' thematic' relations between objects, they often find them more salient or relations taxonomic than per se (seeMarkman 1989). When shown interesting to find another one, children might pick a man told and a car, for example, becausehe drives a car rather than a truck , another vehicle. Given such ' findings from children s classification, the question arises as to how children avoid such thematic interpretations of a novel word. Hutchinson and I proposed that children expect novel terms to refer to objects of like kind (Markman and Hutchinson 1984) . Hearing a novel label, then, should cause children to seek out taxonomic relations even in cases where thematic relations would otherwise be more salient. There is now a substantial body of evidencethat children from about 21J2or 3 expect labels to refer to things of like kind (Baldwin 1989, in press; Hutchinson 1984, Markman and Hutchin son 1984, Waxman and Gelman 1986, Waxman and Kosowski 1990) . I turn now to consider whether the taxonomic assumption is available to babies by the time of the naming explosion. 3.1. ~he taxonomic assumptionat the time of the naming explosion Bauer and Mandler ( 1989) first addressedthis issue in their study of the , they categorization abilities in very young children. As part of their study ' asked whether labeling would increase 16- 31-month -old children s tendency to sort taxonomically . Unexpectedly, however, even the youngest children in their study were sorting taxonomically from the start. That is, even with no labels children were sorting taxonomically about 75% of the time. Labeling did not increasethis already high level of performance. Bauer and Mandler ( 1989) have thus convincingly demonstrated that quite young children are capable of sorting taxonomically . They also argue that there may not be any general thematic preference. Because of the already high rate of sorting taxonomically, however, they were unable to test whether children of this age adhere to the taxonomic assumption. That is, it is still important to know whether there are situations in which very young children show thematic preferencesand, if so, whether hearing a label will cause them to shift to taxonomic sorting. Backscheiderand I addressedthis by changing aspectsof ' Bauer and Mandler s procedure that resulted in children responding taxonomically from the start.

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205

One reason why Bauer and Mandler ( 1989) achieved such a high rate of taxonomic responding in their young children is that they used areinforcement procedure whereby they briefly pretrained children to selecttaxonomicand maintained this selectivereinforcementof taxonomic choicesthroughout ally the testing procedure. The selective reinforcement clearly mattered becausein a control study Bauer and Mandler achievedan equally high rate of thematic responding by selectively reinforcing thematic rather than taxonomic responses . Since they demonstrated that selective reinforcement is a to influence children' s responses powerful way , Backscheiderand I avoided selectivereinforcement (as did all earlier studies with older children). Other differencesbetween our procedure and Bauer and Mandler ' s ( 1989) are that we used pictures instead of objects, we used items whose thematic relations we thought would be better known to 18-month -olds, and we used an up/ down placemen,t of thematic and taxonomic choices instead of left/right . Finally, Bauer and Mandler counterbalanced the position of thematic and taxonomic choices by alternating the left /right placement from trial to trial . This alternation is unfortunate especially when coupled with a reinforcement procedure. Children may have simply learned the correct answer changes sidesevery trial . We counterbalancedside but not by alternating from trial to trial . The major difference between the studies, however, is that we did not differentially reinforce taxonomic responding. Thirty -three children participated in our study. They ranged in age from 18 to 25 months with a mean age of 21.5 months. The experimental materials consisted of ten triads, each containing one target picture, one picture thematically related to the target, and one picture taxonomically related to the target picture. We selectedthematic relations that we thought would be highly familiar to even very young children. The taxonomic match belonged to the same basic level category as the target but , where possible, came from distinctive subordinate categories. The ten triads are listed in table 1. The experimental questions were preceded by a set of four warm-up questions designed to clarify the instructions and procedure but not to differentially reinforce either taxonomic or thematic responding. The warmup questions and the experimental questions were oddity tasks, where children viewed a target picture and then selectedone of two choice pictures. To begin, children were introduced to a frog hand-puppet who manipulated the pictures. They were asked to help the frog find the pictures it wanted. The children were told that the frog had just gotten a new house, and wanted things to put in its house. In order to ensure that children gave unambiguous , they were shown how to place the pictures they selectedin the frog responses

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E.M . Markman I Early languageacquisition

Table I 's study Experimentalitemsfrom Markmanand Backscheider Choices

Target

Taxonomic

Thematic

Sitting baby Bottle Chair Rabbit cup Foot Glasses Blue scoop shovel

Lying baby Bottle Chair

Stroller

Spoon Toilet paper Mitten

Spoon Toilet paper Mitten

Baby Sitter Pitcher Shoe

Cup Foot Glasses Red shovel

' puppet s mouth . There

were

two

Eyes Pail Cereal in bowl Toilet Hand

experimental

conditions

, the No

Label

Conditionand the Novel Labelcondition. 3.1.1. Warm-up questions For the wanD-up questions, children were shown a target picture and then had to select one of two pictures, one of which was an unrelated distractor. The other picture, the correct choice, was thematically related to the target for half of the trials and taxonomically related for the other half. The items used for the wanD-up questions are listed in table 2. Table2 ' Warm-up itemsfrom Markmanand Backscheiders study Target

Choices . Taxonomic

match

Thematic match

Distractor

Hat

Hat

Head

Car interior

Watch

Watch

Wrist

Shopping cart Hair

Shopping cart Hair

Bag of groceries Brush

Road Pillow Pot

.

In a single trial the child saw either the taxonomic match or the thematic match , not both . The distractor was always present .

The experimenterplacedthe targetpicture(for examplea hat) on the table ' ' and askedthe child to ' look at this picture' or seethis , etc. Then the two

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~. acquisition Ear'v jranguag

207

choice pictures were placed on a magnetic board, one above the other. (Pilot work suggestedthat a vertical alignment of the pictures produced fewer responseblasesbased on position than did a horizontal alignment.) The top/ bottom position of the random distractor and correct picture was counterbalanced . The target picture was held next to the top picture while the ' ' experimenter asked Is this another one? and then held next to the bottom ' picture while the experimenter asked or is this another one?' When children selectedthe wrong picture they were told that that was not the one that the frog wanted and were encouragedto make another selection. For the warmup questions, the frog would not accept the wrong picture - it would keep its mouth closed and shake its head, etc. When children selected the correct choice the frog opened its mouth to take the picture and enthusiastically thanked them, saying ' Yeah! Yeah! That is just the one I wanted. Thank ' you , kissed the child , etc. The experimenter then explained why that was the picture the frog wanted, describing either the taxonomic relation betweenthe target and the picture or the thematic relation as appropriate. For example for the thematic pair hat/ head, the frog said ' That ' s great! A hat goes on a head. Do you ever put a hat on your head? A hat goes on a head, they go ' ' ' together . For the taxonomic pair hat/ hat, the frog said That s great! Now I ' have two hats. Look , these are the same, two hats . Thus, the warm-up questions encouraged, explained, and reinforced taxonomic and thematic responsesequally. The procedure for the two experimental conditions was similar to that of the warm-up questions with two exceptions. First , in the procedure proper there was no unrelated distractor. One of the choice pictures was thematically related to the target and the other was taxonomically related to it , as shown in table I . Second, the frog acceptedany choice the child made, that is, there was no selectivereinforcement during the experiment proper. 3.1.2. No label condition To begin each trial , the puppet placed the target picture on the table and said ' Now let' s look at this picture' or ' Here' s a new picture' . Then the two choice pictures were placed on the magnetic board, one above the other. Whether the thematic choice was placed on the top or on the bottom was counterbalancedsuch that for each child half of the time it appeared on the top and half the time on the bottom . The order of presentation of the items was randomly determined for each child. Once the child saw the target ' ' picture, the puppet asked the child to find another one . It held the target ' picture next to each of the choice pictures, asking Is this another one, or is

E.M . Markman I Early languageDCQuisiliOIl

this another one?' The frog then held the target between the two pictures while the child selectedone of them and placed it in the frog puppet' s mouth. The experimenter took the target out of the frog ' s mouth as the child moved his or her choice over to the frog . Children were enthusiastically thanked on every trial , regardlessof which picture they chose. 3.1.3. Novel label condition The materials and procedure for the Novel Label Condition were identical to those of the No Label Condition except that children in this condition were told that the puppet would sometimes speak in puppet talk and the puppet gave each target picture a novel label. For example, the puppet would show the child the target picture saying ' Now I am going to show you a sud. ' Look at this, it is a sud. Can you find another sudl When children were ' making their choices the puppet said, e.g., Is this another sud or is this another sud1' Ten nonsensesyllables were used as the novel labels and were randomly assignedto the targets for each child. The first question this study addressedwas whether children as young as 18 to 24 months will show thematic preferencesat all. In marked contrast to Bauer and Mandler ' s ( 1989) findings, these young children did show a thematic bias. When children in the No Label Condition were asked to choose between an object that was from the samecategory as the target and one that was thematically related to it , they chose the taxonomic match only 32% of the time, which was significantly less than chance, t ( 15) = 4.78, p < O.OOI. That is, they chose thematically 68% of the time. Thus, when children are not selectivelyreinforced for choosing taxonomic items and when the thematic relations are geared towards what would be well-known to even 18-month -olds, quite young children will reveal the thematic blasesoften seen ' in older children. This does not contradict Bauer and Mandler s claim that these young children are capable of grouping the objects on the basis of common categories, but it does establish that when the thematic relations are well-known and when children are not reinforced for one type of responseor another they prefer to organize objects thematically. Given that for theseitems, theseyoung children do show thematic blases, it then makes senseto ask whether hearing an object labeled will help them override their thematic preferencein favor of taxonomic relations. As predicted , there was a highly significant effect of condition , with children in the Novel Label condition picking taxonomically fully 77% of the time compared to 32% of the time for children in the No Label Condition , F( I , 31) = 66.58, P < 0.000I . Children hearing an object labeled selected a taxonomic match

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well over what would be expected by chance, 1( 16) = 6.75, p < O.OOOI . Thus, these young children do adhere to the taxonomic assumption. They extend object labels to other objects of like kind rather than to objects that are thematically related. Wasow and I have conducted subsequent studies to detennine if these results would replicate with babies 16 to 18 months old. Several changesin procedure were made to accommodate to the younger children. We used objects instead of pictures and reduced the number of questions that children were asked. The experimental triads that were used are presentedin table 3. The procedure was otherwise quite similar to that of Backscheider and Markman , including use of wanD-up questions. Thirty -two 16-month -olds and 32 18-month-olds participated in this study, half of each age group in eachcondition . As before 18-month -olds honored the taxonomic assumption. First , when in the No Label condition , 18-month -olds showed a clear thematic bias selecting the taxonomic choice only 28% of the time, which is below chance, 1( 15) = 10.97, p < O.OOOI . When the target object was given a novel label, the 18-month -olds significantly increased their taxonomic selections , now picking a member of the same category 54% of the time, 1(30) = 3.34, p < 0.005. Table3 Itemsfrom Markmanand Wasow's studywith familiar objects

Target

Choices Taxonomic

Thematic

Felt doll hat Plasticdoll hat Doll head Whitedoll-sizesock Yellow toddler-sizesock Doll-sizefoot " Smallerdoll (approx. 3" ) Babydoll (approx. 5 ) Doll-sizebottle Red& whiteadult-sizetoothbrushPink child-sizetoothbrush Setof plasticteeth Pink plasticdollhousetable White woodendollhousetable Pink plasticdollhousechair Yellowplasticpail Redplasticpail Yellow& white~plasticshovel

We did not find this labeling effect with 16-month -olds, however. The 16month-olds did find the thematic relations salient, picking taxonomically only 34% of the time in the No Label condition , which was less than chance, 1( 15) = 3.76, p < O.OO2 . But labeling had no effect on their selections, with babies selecting taxonomically only 39% of the time in the Novel Label condition . One possible reason for our failure to replicate the labeling effect with 16month-olds is that in this procedure we provide a novel label for a familiar

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object and then look to seehow the child interpreted the label. As I will argue later, children find it more difficult to learn second labels for objects because this violates mutual exclusivity, another word -learning constraint. Other studies mimimized the conflict betweenmutual exclusivity and the taxonomic assumptions by telling children that the novel word was a word in puppet language or a foreign language (Markman and Hutchinson 1984, Waxman and Gelman 1986) . Although older children have been shown to treat mutual exclusivity as applying within a single language, not acrosslanguages(Au and Glusman 1990), 16-month -olds would not have understood a discussion of puppet language. To test the possibility that the conflict between mutual exclusivity and the taxonomic assumption was confusing the 16-month -olds, Wasow and I ran another version of the study, this time using novel objects. Thirty -two 16-month-old babies were introduced to novel triads of toys where two of the toys were similar in appearanceand two were related by some thematic relation we demonstrated. For example, two honey dippers of different colors were novel taxonomic pairs and one honey dipper was scraped against a plastic grid to demonstrate the thematic relation. Babies were then shown a target, e.g., a honey dipper, heard it labeled or not , and were then depending on the condition , asked to find another one or another X (where X was the novel label) . The full set of novel items used is described in table 4. Table 4 ' Tern~ frnm Markmal1 and Wasow' s study with novel objects

Target

Choices Taxonomic

Thematic

Smallgreenspongecircle

Large yellow spongecircle

Smallorangeblock

Largeblueblock

Red ' person' peg Largered propellor

Yellow ' person' peg Smallyellowpropellor

Wooden car with round hole Red helicopter (with post to hold propellor)

Yellowhoneydipper DecoratedPVC pipe

Greenhoneydipper Plain PVCpipe

Yellow plasticgrid Decoratedfunnel

Plastic' tub' containerwith squarecut out in lid

E.M . Markman / Early languageacquisition

Once again we failed to find an effect of labeling with 16-month -olds. Babies selectedthe taxonomic choice 40% of the time when the object was unlabeled and 44% of the time when it was labeled. Our avoiding second labels for objects did not improve babies' performance in the labeled condition . One possibility, of course, is that 16-month -olds lack the taxonomic assumption. Another is that the oddity task we have been using is insensitive to the knowledge babies have. To reveal use of the taxonomic assumption in this task, babies must inhibit a dominant response. We deliberately selected thematic choices that would be preferred by babies this age. Being asked for "a dax' for example may not be compelling enough to prevent babies from ' ' what doing they most prefer, even if they do interpret dax as referring to objects of like kind . Thus, our failure to find the labeling effect with the 16-month -olds might be partially acCounted for by the requirements of the oddity task. The taxonomic assumption may not be strong enough to allow young children to inhibit reaching for a preferred object. Support for this interpretation comes from work from Waxman and her colleagues, who found that labels highlight categorical structure for even 12and 13-month-olds (Waxman, this volume; Waxman and Helm 1991, Mar kow and Waxman 1992). Instead of an oddity task where children would need to .inhibit a dominant thematic response to reveal knowledge of the taxonomic assumption, Waxman and Helm ( 1991) and Markow and Waxman ( 1992) used a manual habituation procedure which assessedwhether babies could notice and distinguish two different categories of objects. The ' hypothesis being tested is that words should enhance babies tendency to notice object categories. The prediction was that labeling objects should ( I ) increase the rate of habituation to category exemplars and (2) increase the degree of dishabituation to an object from a different category. In this procedure, babies are first familiarized with four toys from a given category (e.g., four cars or four animals) . Children were presentedwith each toy, one at a time for 30 secondseach. On analogy with visual habituation tasks, a decrementin the time spent exploring the last toy compared with the first was used as an index of habituation . After the familiarization trials , babies were presentedwith a new exemplar from the old category and an object from the novel category. Here, again on analogy with standard habituation tasks, babies who had best formed the category would be expected to show a greater interest in the object from the novel category than in the object from the original category. For some of the babies the experimenter labeled the

E.M . Markman / Early languageacquisition

' ' object during the familiarization phrase saying, e.g., Look at the car . For some babies the experimenterdrew attention to the object without labeling it ' ' saying, e.g., Look at this . As predicted, labeling the objects improved babies' ability to categorizeas measuredboth by rate of habituation to within category exemplarsand by dishabituation to a novel category (Waxman and Helm 1991, Markow and Waxman 1992). Moreover, Markow and Waxman ' discoveredthat at 12 months labeling objects improved babies categorization even when adjectivesrather than nouns were used to refer to the objects. This finding is of interest becauseit supports the idea that babies first treat words as referring to objects of like kind rather than treating only nouns that way. One-year-olds, presumably with minimal knowledge of grammatical form class, were better able to categorize objects if they were labeled regardlessof whether a noun or adjective was used as the label. ' At this point it is of interest to consider briefly Bloom s (this volume) alternative framework for constraints on word meaning. Bloom views the postulation of particular constraints such as the taxonomic and whole-object assumptions as unmotivated and corrects this in his model with an elegant systemthat generatesconstraints to conform to universal grammar-cognition ' mappings. Bloom s systematicanalysis provides a clear statement of what the endpoint of development should be. Where we disagreeis in what to attribute to the very early phasesof language learning - the time before children have mastered grammatical form class. On the view I have proposed very young children will break into the systemby assumingthat a word refers to a whole object (the whole object assumption) and is extended to things of like kind ' (the taxonomic assumption). Bloom s account, which is bolstered by counterexample to my formulation , is that children map count nouns on to kinds of individuals rather than kinds of objects. Yet , this may describe adevelop mental achievement rather than the initial state. Babies may treat terms as referring to objects but with time note the regularity with which count nouns refer to objects. Once this correlation is establishedchildren may then be able ' ' to metaphorically extend object-like or individual status to non-objects that ' ' ' ' are referred to with count nouns such as a forest or a lecture . Second, on ' my account as well as Waxman s, young children rely on word -learning constraints before they have mastered grammatical form class. Very young children should err by treating adjectives, for example, as referring to kinds of objects. The work just described (Markow and Waxman 1992) is one source of evidencethat before children have masteredthe noun/adjective contrast in ' English, adjectivesas well as nouns enhanceone-year-old s attention to kinds of objects.

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' Labeling has been found to enhance even younger babies attention to objects. Baldwin and I found that babies from 10- 14 months old attended more to toys that had been labeled compared to ones that had not ( Baldwin and Markman 1989) . In a second study, we compared labeling to another ' powerful means of directing babies attention , namely pointing . Although labeling did not increasebabies attention over pointing at the time pointing occurred, during a subsequentplay period babies attended more to toys that had been labeled than to those that had not . Thus, labeling may sustain babies' interest in objects beyond the time the labeling occurs. By helping babies sustain their attention to relevant objects, this labeling effect may help babies notice and remember the word -object correspondences. It is not yet known whether this labeling effect is caused by labels per se or whether other nonlinguistic sounds would have the same effect (see Baldwin and Markman 1989 for other possible explanations as well) . So far , the existing data are inconsistent. Waxman and Balaban ( 1992) have found that words but not tones increased attention to object categories in 9-month -olds. On the other hand, Roberts and Jacob ( 1991) found that music as well as words facilitated object categorization in infants . Whether the effect is specific to words or not , words do heighten babies' attention to objects and object categories. Taken together, then, the experimental findings document that babies from 12- 18 m"Onths(and maybe even younger) use the taxonomic assumption to help them determine the appropriate referents of a word. This conclusion from the experimental data is supported by the results of Huttenlocher and ' Smiley s ( 1987) study of naturalistic data. They generateda set of criteria to distinguish thematic (complexive) extensionsof words from taxonomic extensions , arguing that not every use of a word by a young child should be taken as a simple label of an object. They followed severalchildren from the time of their first word (around 13 months for most of the children) and periodically recorded both the words children produced and details of the situation and context in which utterances occurred. For example, a child who reaches towards a cookie jar saying ' cookie, cookie' with an insistent request intonation , should not be interpreted as labeling the cookie jar as a cookie. Instead, the child is most likely requesting a cookie. Using coding categories that ' capture reasonable interpretations of children s utterances, they found that from the start children use words to refer to objects of like kind . Thus, evidence from experimental and naturalistic studies alike indicate that the taxonomic assumption is available to babies who have not yet undergone the naming explosion.

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Although the taxonornic assurnption goesa long way in reducing the kinds of hypothesesbabies need to consider in figuring out the rneaning of a new word , it by no rneans solves the problern. Babies rnay be led to treat novel words (or nouns) as referring to kinds of objects but that still leavesopen the question of which kind . This problern has been extensively addressed by Waxrnan and her colleaguesand is reviewed in Waxrnan (this volurne) . To ' briefly surnrnarize, labels facilitate young children s attention to objects at sorne hierarchical levels but rnight actually interfere with their ability to categorizeat other levels. Young children hearing a noun expect it to refer to categories either at a basic or superordinate level of categorization, but do not expect it to refer to the distinctions rnade at subordinate levels of categorization. Rather, they expect this level of detail to be indicated by ' adjectives. Waxrnan s work reveals the interaction between use of wordlearning constraints, grarnrnatical form class, and conceptual structure. Not only does the taxonornic assurnption leave open the question of which kind of object is being referred to , it even leavesopen which object is being referred to. As Baldwin ( 1991) pointed out , in normal environrnents that babies find thernselvesin , there are often rnany candidate objects around that could serveas potential referents for a new word. Even if babies are prepared to treat a novel word as referring to , say, a basic level category, they rnust figure out which one. One possibility is that babies rnay treat a novel word as refelTing to whatever novel object they are attending to. Whenever babiesand adults are focussing on the sarne object, this would lead babies to correctly identify the referent of a novel term. On those occasions, however, when the adult was in fact labeling an object other than the one the baby was focused on, the baby would wrongly interpret the new word and would rnake a rnapping error. Such rnapping errors appear to be very rare, although there is evidence that babies learn words rnore readily when parents tend to label what their baby is attending to (Tornasello and Farrar 1986) . Baldwin ( 1991) suggested that babies could avoid rnapping errors if they rnonitored the ' speakers focus of attention. If babies recognize that the object they are interested in is not the one the speakeris attending to , then they would know not to treat the word as a label for their object. Baldwin tested whether ' babies use information about a speakers focus of attention in inferring the referent of a novel word or whether they rnapped a novel word to whatever novel object they were interested in. To test this, she provided novel labels to ' ' 16- 19-rnonth-old babies in one of two conditions. In the discrepant label condition , babies were given a toy to play with . Once the experirnenter was assured that the baby was exarnining the toy the experirnenter provided a

E.M . Markman I Early languageacquisition

215

novel label saying, e.g., ' It ' s a toma' . Instead of looking at the baby or the ' ' toy , however, the experimentergazedinto an opaque bucket as she said It s a ' toma . Thus, the baby heard the novel label while looking at a novel toy but while the speaker looked into a bucket that contained a second toy . In the ' follow -in ' labeling condition , the experimenter looked at the visible toy while she provided the novel label. In the follow -in labeling condition , babies of both ages treated the novel word as referring to the visible toy . Of more interest is what happenedin the discrepant conditions. The results were quite clear: at neither age did babies treat the novel word as referring to the visible toy even though they were looking at the toy at the time they heard the label. By monitoring the eye-gaze, posture, direction of voice, or some other cues to the speaker's focus of attention babies avoided making a mapping error. The 16- 17-month -olds avoided errors by simply failing to learn the new word. The 18- 19-month -olds not only avoided errors, but were able to infer that the new word referred to the object that was hidden in the bucket at the time of labeling. Baldwin' s results reveal how babies' use of word-learning constraints is coordinated with their construal of the communicative intent of the speaker.

4. The wbole- objeet assumption

The whole-object assumption states that babies should treat a novel label as referring to an object rather than a part , substance, color , movement, etc. There is somecontroversy as to whether young children treat a novel label as referring to the shapeof an object rather than the object per se. Some studies have found that young children will extend an object label to things of the sameshaperather than those of the samecolor , or texture (Au 1989, Au and Markman 1987, Baldwin 1989, Landau et al. 1988, Ward et al. 1989) . One interpretation of these findings, however, is that children are treating the terms as referring to whole objects of like kind , and that shape is a ' particularly reliable clue to an object s taxonomic category. Sola et al. ( 1991) reinforce the conclusion that it is the object, not the shape, that children are responding to in that they do not treat words as referring to the shape of non-solid substances even when different substances were arranged into common shapes. Baldwin (in press) has found that , on the one hand, children will extend a label on the basis of shapewhen there is no obvious taxonomic category, but , on the other hand, children will extend a label on the basis of

E.M. MarkmanI Early language acquisition

taxonomic category even when the objects in question do not have the same shape. Moreover, Landau (this volume) along with Becker and Ward ( 1991) have found that preschoolers treat novel terms as labels for objects rather than shape in that they treat a term for a worm -like animal as referring to another worm twisted into a different configuration . (Landau, however, argues for a different interpretation of these results. In particular she argues that children are still responding on the basis of shapeibut shape now is defined as the possible shape transformations an object of a given shape can undergo.) In addition , there are developmental differences in the way this whole-object bias interacts with grammatical form class (Landau et al., in press; Landau, this volume) . Older children and adults will treat a novel noun as referring to the kind of object but treat an adjective as referring to a property such as texture. But the youngest children treated even novel adjectives as referring to kinds of objects. Here again we see that when knowledge of grammatical form classis weak, word -learning constraints such ' as the whole-object assumption dominate the child s interpretation of a novel term. Taken together, these findings suggestthat children attempt to honor the whole object and taxonomic assumptions per se, rather than treating words as shapeterms. Further support for the whole-object assumption comes from studies that have documented that children interpret a novel term as a label for an object and not its part (Markman and Wachtel 1988, Mervis and Long 1987) and for an object over its substance(Markman and Wachtel 1988, Sola et al. 1991) . 4.1. The whole-object assumptionat the time of the naming explosion Although the whole-object assumption has received experimental support, only Mervis and Long ( 1987) examined babies around the age of the naming ' explosion. Moreover, none of the studies (except perhaps Landau s, this volume) provided a strong test of the whole-object assumption. Babies might map words onto objects not becauseof a whole object assumption per se, but simply becauseobjects are salient and babies might map novel words to whatever is most salient at the time of labeling. Thus a stringent test of the whole-object assumption requires examining whether babies treat novel words as referring to objects even when an object is not the most salient aspectof the environment. Woodward ( 1992) has provided such a test. Woodward ( 1992) had babies view two video monitors. On one screen babies viewed a dynamic substancein motion , such as flowing lava. On the

E.M. Markman/ Early /anxuaR .e acquisition

217

other screenthe babies viewed a static novel object. When the screenswere turned on and babies allowed to watch freely, they clearly preferred the swirling substancesto the static objects. Thus, Woodward created a situation where the object was lesssalient than the substancein motion . On some trials babies heard a label that could be interpreted as referring either to an object or substance. The prediction from the whole-object assumption is that hearing a label should cause babies to shift attention more to the whole object. This hypothesis was confirmed for 18-month-olds (though lessclearly for the 24-month -olds) . Around the time of the naming explosion, then, babies treat novel words as referring to objects per se, rather than to . whatever is most salient. Testing a somewhat different hypothesis, Echois also has evidence suggesting that well before the time of the naming explosion babies honor the whole-object assumption, but that younger babies (8- to 10-month -olds) may not. Echois ( 1990, 1991) asked whether young babies might map labels to whatever in the environment is consistent rather than to objects per se. She used an habituationjdishabituation procedure where babies heard labels either in the presenceof consistent objects with varying motions or consistent motions with varying objects. Trends in the pattern of habituation and dishabituation led Echois to speculatethat there is a developmentalshift from 8- 10 months to 13- 15 months in how babies are affected by labeling. The younger babies appeared to focus on what was consistent when they heard a label while the older ones focused on objects per se. The older babies were only 13 to 15 months old , however. Woodward ' s visual preferencestudy and Echols' habituation studies both suggest that the whole-object assumption is in place by the time of the ' naming explosion. By focussing children s attention on objects as the most likely referent of a novel word , the whole-object assumption greatly reduces the number of hypotheseschildren need to consider for the meaning of a novel term. The whole-object assumption thus promotes the rapid learning of object labels. While the whole-object assumption can account for the speed with which children acquire names for objects, it poses an obstacle for , colors, texture, and other properties of learning terms for parts, substances objects. With only the whole-object assumption to guide their interpretation of novel words, babies would be limited to learning only object labels. One of the functions of the mutual exclusivity assumption discussednext is that it can override the whole-object assumption, freeing children to learn a greater variety of terms.

E.M. MarkmanI Early language acquisition 5. The mutual exclaivity

assumption

The mutual exclusivity assumption leads children to prefer only one label for an object. This assumption is stronger than a related one of contrast (Clark 1987, 1990, 1991), which is that any two words contrast in meaning. ' ' ' ' Although words such as car and vehicle contrast in meaning with one being a superordinate of the other, they violate mutual exclusivity in that one ' ' ' ' object can be called both car and vehicle . In some cases, mutual exclusivity comesinto conflict with the whole-object assumption. Supposea child hears a ' ' novel word , say finial in the presenceof a novel object, a pagoda. On the ' ' whole-object assumption, the child should (mistakenly) treat finial as referring to the pagoda. Supposeinstead that another child who has learned that a ' ' ' ' pagoda is called pagoda also hears the novel word finial in the presenceof the pagoda. Here the whole-object and mutual exclusivity assumptions are brought into conflict. As before, the whole-object assumption would lead ' ' children to interpret finial as referring to the pagoda. In contrast, children ' ' ' ' who know a pagoda is called a pagoda are led to avoid treating finial as ' ' yet another word for the same object. By rejecting finial as a second label children would then be motivated to find some other referent for the term. , Thus, mutual exclusivity can motivate children to find salient parts, substances and properties of objects as referents for novel terms. As predicted by mutual exclusivity, preschool children are in fact better able to .learn novel terms for parts and substancesif taught on objects with known labels (Markman and Wachtel 1988) . More generally children should be better able to learn a variety of property terms when taught on objects with known labels. Mutual exclusivity can then help override the whole object assumption allowing as word the novel to children something other than an object label. interpret Mutual exclusivity may also enable children to override the taxonomic assumption to enable them to better learn proper names (Hall 1991) . While the taxonomic assumption leads children to interpret new terms as referring to objects of like kind , proper names refer to particular individuals , not kinds. Hall ( 1991) predicted that children should be better able to learn proper namesfor familiar objects with known labels than for objects without known labels. To test this Hall ( 1991) relied on the logic first put forward by Katz et ale( 1974) . Katz et ale taught children a new label for an object. They then looked to see whether children restricted the new term to the labeled object or whether they extendedit to a highly similar secondobject. Choosing the original object above chance was taken as evidencechildren treated the term as a proper name; indifference between the two objects was taken as

E.M . Markman / Early languageacquisition

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evidence they treated the term as a common name. Katz et al. ( 1974) manipulated two sourcesof information about whether something might be a proper name or not. The first was grammatical form class, in particular , ' whether the novel term took an article or not , e.g., ' a dax' vs. ' Dax . The second was the type of object that was labeled, in particular , animate-like things which are appropriate referents of proper names, in this case dolls, versus inanimate objects unlikely to be treated as unique individuals , in this caseblocks. Their results for girls suggestedthat when both the grammatical form class and the conceptual domain were appropriate, girls treated the novel term as a proper name. That is, when a doll was called ' Dax ' , girls interpreted Dax as a name for that doll and not the other one. When the doll was called ' a dax' , girls treated the term as applying to both dolls. No matter whether the block was called by common or proper name, girls treated the new word as referring to both blocks. A partial replication of this stud)' suggestedthat 18-month -old girls would also distinguish betweenproper and common names for dolls. These results did not hold up for the boys, however. Two -year-old boys were at chance for all object selections, even when hearing a proper name for a doll . Gelman and Taylor ( 1984) replicated the Katz et al. ( 1974) study with some improvements and modifications. They addressedthe concern that evidence for treating a term as a common noun was undifferentiated from chance performance. By adding other distractors to the responseset, they avoided this problem. Gelman and Taylor ( 1984) also used unfamiliar rather than the familiar objects that Katz et al. had used. Testing somewhat older children (2- 3-year-olds), Gelman and Taylor found that boys as well as girls treated terms as common nouns except in the casewhere proper nameswere used to refer to animate-like objects (stuffed animals) . To return to Hall ( 1991), then, the question is whether, along with grammatical form class and conceptual domain, mutual exclusivity is used to help children learn proper names. By overcoming the tendency to treat a novel label as a second term referring to things of like kind , mutual exclusivity could promote the interpretation of a new term as a proper name. Second labels for objects should be more likely than first labels to be construed as proper names. To test this Hall ran a partial replication of Gelman and Taylor ( 1984), running only the condition that resulted in proper name interpretations in the prior work . That is, two - and three-year olds were taught proper names for animate objects. They were taught in one of two conditions: either the animate objects had known names or they did not. Overall, Hall ( 1991) again replicated Gelman and Taylor ( 1984) and Katz et

E.M. MarkmanI Early language acquisition

al. ( 1974) with children treating the novel term as referring to the individual object labeled at above chance levels. Moreover, as predicted, children were more likely to treat the novel term as a proper name when they already knew another common name for the object. Combining the results of Hall ( 1991) with those of Gelman and Taylor ( 1991), we can conclude that young children recruit information from three sourcesto determine how to interpret a novel term: When the conceptual domain is appropriate, when the syntactic information is consistent with a proper name interpretation , and when mutual exclusivity can help override the taxonomic assumption, young children are most likely to treat the term as a proper name. These studies with parts and substancesand proper and common names lead to the general conclusion that some word -learning constraints can be used to moderate or override others. Mutual exclusivity can override the whole-object assumption leading children to learn terms for parts, substances, and other attributes of objects. It can also override the taxonomic assumption , thereby helping children interpret a proper name as a term for a unique individual . ' 5.1. Mutual exclusivity as a guide to a word s referent Another advantage of mutual exclusivity is that it can provide an indirect means of inferring the meaning of a novel word. Suppose a child hears ' ' ' someoneuse a novel object label, for example Look at the gadget or Please ' bring me the gadget . The child looks around and seesone or more objects with known names - say, a ball , and a novel object, say, a garlic press. By ' ' ' mutual exclusivity the child should reason that gadget can t refer to the ball ' ' becauseit is a ball , so it must refer to the garlic press, the only novel object around. In this case the child can fulfill both the whole-object and mutual exclusivity assumptions and use them to infer the meaning of a novel word . Adults and children alike use mutual exclusivity to figure out which object a novel label refers to without anyone explicitly pointing to or otherwise indicating the object (Au and Glusman 1990, Dockrell and Campbell 1986, Golinkotr et al. 1992b, Hutchinson 1986, Markman and Wachtel 1988, Merriman and Bowman 1989). Golinkotr et al. ( 1992b) went a step further and documented not only that mutual exclusivity provides children with an indirect means of inferring the meaning of a novel term but that that term then functions as a familiar word -year-olds used mutual in the child ' s lexicon. They showed that after 21J2 exclusivity to infer the referent of a novel term, they treated the referent as an

E.M . Markman I Early languageacquisition

object with a known label which in turn prevented the children from accepting another novel label for that object. Two -year-olds' successat using mutual exclusivity to infer the referent of a novel term belies the inferential requirements of this task. The logic of this ' problem is of the form of a disjunctive syllogism: The novel word must refer to either object A or to object B. It is not A (by mutual exclusivity), therefore, it must be B' . Hutchinson ( 1986) has found , in fact, that this logic of the problem may pose a problem for developmentally delayed children even when they are matched in mental age to normal children. In her task, normal and developmentally delayed children were given pairs of objects where one object had a known name and the other did not. The normal children were 2, 2Y2 and 3 years of age and, as expected, at all age groups they chose the unfamiliar object at above chance levels as the referent of a novel label. The performance for the developmentally delayed children showed a marked developmental difference with children matched in mental age to the 2Y2- and 3-year-olds selecting the novel object at above change levels, but with children matched in mental age to the 20- 24- month-olds failing to do so. Thesechildren did not select the novel object as the referent of the novel word even though normally developing children of 20- 24 months did. It was not until retarded children reacheda mental age of 28 months that they seemed capable of using mutual exclusivity to infer the appropriate referent of a novel term. One possible reason for this delay is that the logic of the problem is particularly slow to develop in the delayed children. 5.2. Mutual exclusivity at the time of the naming explosion There are two concerns that have been raised about whether children around the age of the naming explosion can use mutual exclusivity to infer the meaning of a novel term. The first is that this use of mutual exclusivity has been documented only in children from two years of age and up . Studies with younger children are needed. Second, an alternative explanation for these results has been proposed by Merriman and Bowman 1989 . ( ) They argued that children might map a novel word to a novel object in these studies becausethey are predisposed to fill lexical gaps - to find first labels for objects. Thus , when children encounter an object for which they do not know a label , they should seek out its name. Children might be mapping the novel label to the novel object becausethey desire a name for the novel object, not because they reject a second label for the familiar object .

E.M. Markman/ Early language acquisition

Wasow and I have addressed both of these concerns in a recent set of studies(Markman and Wasow, in preparation) . We asked whether children at around the age of the naming explosion can use mutual exclusivity unaided by a bias to fill lexical gaps to infer an appropriate referent of a term. The lexical gap hypothesis states that in the presenceof a novel object, children will seekits name. With no novel object visible, no lexical gap can be created. We ruled out the possibility of children using a lexical gap strategy by not having a novel object visible at the time of labeling. At the time they heard the novel label children saw only a familiar object and a bucket which served as a possible location for objects. The prediction from mutual exclusivity is that upon hearing a novel label children should reject it as a secondlabel for the visible familiar object and search for an appropriate referent. This search could consist of looking around the room , or on the floor , etc. or by wanting to seewhat is in the bucket. We found that babies as young as 15 months of age can use mutual exclusivity to reject a second label for an object and to motivate them to search for another potential referent. In this case, not only do the babies need to use the disjunctive logic to reject the label as a label for object A , they infer it applies to some unknown object B that is not visible at the time. It is remarkable that this very demanding test of the use of mutual exclusivity is passedby such young babies. Another less demanding test of the use of mutual exclusivity in young children is to seewhether mutual exclusivity simply causeschildren to reject second labels for objects, without requiring the children to make any inferences beyond that. The prediction is simply that second labels for objects should be more difficult to learn than first labels. Although there are a number of studies that document young children are capable of learning second labels for objects (Banigan and Mervis 1988, Mervis et al. 1991, Taylor and Gelman 1989, Tomasello et al. 1988, Waxman and Senghas1990) all except Mervis et al. ( 1991) were conducted for other purposesand none of thesecompared the learning to first labels. The prediction is not that second labels should be impossible for young children to learn, but rather that they should be harder becausechildren prefer not to have secondlabels for things. Liittschwager and I tested this hypothesis with 18- and 24-month -olds (Liitschwager and Markman 1991) . Children were briefly taught either a first label for a novel object or a second label for an object with a known first label. The results for the 18-month -olds were as expected- they success fully learned a new first label for an object but failed to learn a secondlabel. The results for the 24-month -olds were more complicated and reveal another subtlety to the way constraints on word learning work . Not only did the 24-

E.M . Markman I Early languageacquisition

month-olds success fully learn a new first label after brief training , but they learned a second label just as well. These young children clearly violated mutual exclusivity to acquire this second label. We then ran a second study with 24-month-olds to see what would happen if the task were made somewhat more demanding. Now children were required to learn two new labels rather than just one - either two new first labels or two new second labels. In contrast to the earlier results, the two -year-olds now showed evidenceof using mutual exclusivity. They succeededat learning two new first labels but failed to learn the second labels for objects. This suggestsanother way in which word -learning constraints function as default assumptions: children may rely on the default assumptionsmore heavily when the demands of the task increase.

6. Conclusions

Word -learning constraints were presente~ as necessaryto help children cope with the inductive problem involved in learning a novel word . An unconstrained, unbiased learning mechanismwould be forced to consider too many hypothesesand would be unable to converge on a candidate meaning in a reasonable amount of time. Some constraints on hypothesess are required to explain the fast learning actually seenat around 18 months to two years of age. I reviewed evidence for three specific constraints - the wholeobject, taxonomic, and mutual exclusivity assumptions. Recent work reveals that all three assumptionsare available to babies by the time of the naming explosion. Even for young children, however, other sources of information about a word ' s meaning may be available. When several sourcesof information , such as grammatical form class, eye gaze of the speaker, and all three word-learning constraints converge, word learning should be especially efficient . Yet there remain many interesting issues to be resolved about the complex and subtle interplay of word -learning constraints with each other and with other sourcesof information about a word ' s meaning.

References , manuscript, Brown . Children's useofinfonnation in word learning.Unpublished Au, T.K., 1989 University.

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Au, T.K. and M. Glusman . Theprincipleof mutualexclusivityin word learning: To honor , 1990 or not to honor? Child Development 61, 1474 - 1490 . Au, T.K. and EM . Markman, 1987 . Acquiringword meaningsvia linguisticcontrast. Cognitive 2, 217- 236. Development Baldwin, D.A., 1989 . Prioritiesin children's expectations aboutobjectlabelreference : Form over - 1306 color. Child Development 60, 1291 . Baldwin, D.A., 1991 . Infants' contributionto the achievement of joint reference . Child Development 62, 875-890. Baldwin, D.A., in press . Clarifyingthe role of shapein children's taxonomicassumption . Journal of ExperimentalChild Psychology . Baldwin, D.A. andE.M. Markman, 1989 . Mappingout word-objectrelations: A first step. Child 60 381 398 . Development , . Roleof adult input in youngchildren's categoryevolution, , R. L. andC. B. Mervis, 1988 Banigan II : An experimental study. Child Language15, 493- 505. Bauer, P.J. andJiM . Mandler, 1989 . Taxonomies and triads: Conceptualorganizationin one-totwo-yearolds. CognitivePsychology 21, 156- 184. Becker . Children's useof shapein extendingnovellabelsto animate , A.H. and B.T. Ward, 1991 : versus . CognitiveDevelopment 6, 3- 16. objects Identity posturalchange Bloom, B., 1994 . Possiblenames: The role of syntax-semanticsmappingsin the acquisitionof . Lingua92, 297- 329(this volume). nominals Bloom, L., K. Lifter andJ. Broughton, 1985 . Theconvergence of earlycognitionand languagein the secondyearof life: Problemsin conceptualization and measurement . In: M. Barrett(ed.), Children's single -word speech , 149- 180. New York: Wiley. . The principle of contrast: A constraint on languageacquisition Clark, E.V., 1987 . In : B. MacWhinney(ed.), The 20th Annual CarnegieSymposiumon Cognition, 1- 33. Hillsdale, NJ; Erlbaum. Clark, E.V., 1990 . On the pragmaticsof contrast. Journalof Child Language17, 417- 431. Clark, E.V., 1991.Acquisitionalprinciplesin lexicaldevelopment . In: S.A. Gelman, J.P. Byrnes on languageand thought: Interrelationsin development (eds.), Perspectives , 31- 71. Cambridge . Press University . The development of representational skills. In: K.W. Fischer(ed.), Levels Corrigan, R., 1983 -Bass and transitionsin children's development . , 51- 64. SanFrancisco , CA: Jossey Dockrell, J. and R. Campbell . 1986 Lexical in the , acquisitionstrategies preschoolchild. In: S. Kuczaj, M. Barrett(eds.), The development of word meaning . , 121- 154. Berlin: Springer Dromi, E., 1987 . Early lexicaldevelopment . New York: CambridgeUniversityPress . Echois, C.H., 1990 . An influenceof labelingon infant' s attentionto objectsand consistency : . Paperpresented at the InternationalConference on Implicationsfor word-referentmappings Infant Studies . , Montreal, Quebec , April 1990 . Infant' s attentionto objectsand consistency Echois, C.H., 1991 in linguisticand non-linguistic context. Paper presentedat the Biennial Meeting of the Societyfor Researchin Child . , Seattle , WA , April 1991 Development Fisher, C., L. R. Gleitmanand H. Gleitman, H. 1991 . On the semanticcontentof subcategorization frames.CognitivePsychology23, 331- 392. Fisher, C., D.G. Hall, S. Rakowitzand L. Gleitman, 1994 . Whenit is betterto receivethan to give: Syntacticand conceptualconstraintson vocabularygrowth. Lingua 92, 333- 375 (this volume).

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Gathercole, V.C., 1989 . Contrast: A semantic constraint ? Journalof Child Language16, 685- 702. Gelman, S.A. and M. Taylor, 1984 . How two-year-old childreninterpretproperand common namesfor unfamiliarobjects . Child Development 55, 1535 - 1540 . Golinkoft', R.M., C.B. Mervis and K. Hirsh-Pasek . Early object labels: The casefor , 1992a lexicalprinciples . Unpublishedmanuscript . Golinkoft', R.M., K. Hirsh-Pasek . Young childrenand , L.M. Baileyand N.R. Wenger , 1992b adultsuselexicalprinciplesto learnnewnouns. Developmental Psychology28, 84- 89. Gould, J.L. and P. Marler, 1984 . Ethologyand the natural history of learning. In: P. Marler, H.S. Terrace(eds.), The biologyof learning,47- 74. Berlin: Springer . Hall, D.G., 1991 . Acquiring proper nounsfor familiar and unfamiliaranimateobjects: Two' - 1154 . Child Development 62, 1142 . year-olds word-learningblases . Learninghow to mean. In : E.H. Lenneberg Halliday, M.A.K., 1975 , E. Lenneberg(eds.), Foundationsof languagedevelopment : A multidisciplinaryapproach , Vol. 1, 239- 265. New York: AcademicPress . Hutchinson . Constraintson children's implicit hypotheses , J.E., 1984 about word meanings . , StanfordUniversity, Stanford, CA. Unpublisheddoctoraldissertation Hutchinson . Children's sensitivityto the contrastiveuseof objectcategoryterms. , J.E., 1986 ' 25, 49- 56. Papersand Reportson Child LanguageDevelopment Huttenlocher . Earlyword meanings : Thecasefor objectnames , J. andP. Smiley, 1987 . Cognitive Psychology19, 63- 89. . What' s a name? On thechild' s acquisitionof proper Katz. N., E. BakerandJ. Macnamara , 1974 andcommonnouns. Child Development 45, 469- 473. Landau, B., 1994 . Where's what and what's where: The languageof objectsin space . Lingua92, 259- 296(this volume). Landau, K.B., LiB. Smith and SiS. Jones . The importanceof shapein early lexical , 1988 3, 299- 321. learning.CognitiveDevelopment Landau, B., L. B. Smithand S. Jones . Syntacticcontextand the shapebiasin children's , in press andadultslexicallearning. Journalof Memoryand Language . . Mutual exclusivityas a default assumptionin , J.C. and E.M. Markman, 1991 Liittschwager secondlabellearning. Paperpresented at the biennialmeetingsof the Societyfor Research in Child Development . , Seattle , April 1991 Lock, A., 1980 . The guidedreinventionof language . London: AcademicPress . Markman, EM., 1989 . Categorizationand namingin children: Problemsof induction. Cambridge , MA : MIT Press , BradfordBooks. Markman, E.M., 1992 . Constraintson word learning: Speculations about their nature, origins, and domainspecificity . In : M.R. Gunnar, M.P. Maratsos(eds.), Modularity and constraints in languageand cognition: The MinnesotaSymposiaon Child Psychology , 59- 101. Hillsdale, NJ: Erlbaum. Markman, E.M. and J.E. Hutchinson . Children's sensitivityto constraintson word , 1984 : Taxonomic vs. thematic relations . meaning CognitivePsychology16, 1- 27. Markman, E.M. and GiF. Wachtel, 1988 . Children's useof mutualexclusivityto constrainthe of words. CognitivePsychology 20, 121- 157. meanings Markman, E.M. and J. Wasow, in preparation . Very youngchilren's useof mutualexclusivity . Markow, D.B. and SiR. Waxman . The influenceof labels on 12-month-olds' object , 1992 at the InternationalConference on Infant Studies categoryformation. Paperpresented , Miami, Florida, May 1992 .

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Marler, P. and HiS. Terrace(eds.), 1984 . The biologyof learning. Berlin: Springer . McShane . The development of naming. Linguistics17, 879-905. , J., 1979 Merriman, W.E. and L.L. Bowman . The mutual exclusivitybias in children's word , 1989 . of the for Researchin Child Development54( 3/4), Serial learning Monographs Society No. 220. Mervis, C.B., and L.M. Long, 1987 . Words refer to wholeobjects: Young children's interpretation of the referentof a novelword. Paperpresented at the biennialmeetingof the Society for Research in Child Development , Baltimore, MD. Mervis, C.B., RiM . Golinkoff and J. Bertrand, 1991 . A refutationof the principleof mutual . Paperpresented at the Societyfor Research in Child Development , Seattle , WA. exclusivity . Childrenacquireword meaningcomponents , L.G., H. Gleitmanand L.R. Gleitman, 1992 Naigles from syntacticevidence . In: E. Dromi (ed.), Languageand cognition: A developmental . Norwood, NJ: Ablex. perspective . Structureand strategyin learningto talk. Monographsof the Societyfor Nelson, K., 1973 Research in Child Development 38( 1/ 2), SerialNo. 149. Nelson, K., 1988 . Constraintson word learning? CognitiveDevelopment 3, 221- 246. Nelson, K. and J. Lucariello, 1985 . The development of meaningin first words. In: M. Barrett ' - word speech : Wiley. , 59- 86. Chichester (ed.), Childrens single W. V.O. . Word and object. Cambridge . , 1960 , MA : MIT Press Quine, Roberts . Linguistic versusattentional influenceson nonlinguistic , K. and M. Jacob, 1991 in 15-month-old infants. CognitiveDevelopment 6, 355- 375. categorization Rozin, P. and J. Schull, 1988 . The adaptive -evolutionarypoint of view in experimentalpsychology and , Vol. I. In: R.C. Atkinson, R.J. Herrnstein , G. Lindsey, R.D. Luce(eds.), Perception motivation(2nd ed.), 503- 546. New York: Wiley. Shettleworth . Naturalhistoryandevolutionof learningin nonhumanmammals . In: P. , S.J., 1984 Marler, 8 .S. Terrace(eds.), The biologyof learning, 41~ 33. New York: Springer . . Contentandcontextin earlylexicaldevelopment . , L.S., F. Batesand I. Bretherton , 1981 Snyder Journalof Child Language8, 565- 582. . Ontological categoriesguide young children's , 1991 Sola, N.N., S. Carey and E.S. Spelke inductionsof word meaning:Obj~ t termsand substance terms. Cognition38, 179-211. . Incorporatingnew words into the lexicon: Preliminary Taylor, M. and S.A. Gelman, 1989 59, 411- 419. evidencefor languagehierarchiesin two-year- old children. Child Development . The socialbasesof languageacquisition . SocialDevelopment1, 67- 87. Tomasello , M., 1992 . Object permanence and relational words: A lexical Tomasello , M. and M.J. Farrar, 1986 trainingstudy. Journalof Child Language13, 495- 505. . Theeft'~ t of previouslylearnedwordson Tomasello , M., S. Mannieand L. Werdenschlag , 1988 . Journalof Child Language15, 505- 515. the child' s acquisitionof wordsfor similarreferents Ward, T.BE . Vela, M.L. Peery,S. Lewis, N.K. Bauerand K. Klint , 1989.Whatmakesa vibble . Child Development 60, 214- 224. a vibble: A developmental studyof categorygeneralization . The development of an appreciationof specificlinkagesbetweenlinguistic Waxman , S.R., 1994 . Lingua92, 229- 257(this volume). andconceptualorganization . The influenceof words vs. tones on 9-month-old Waxman , 1992 , S.R. and M.T. Balaban . Paper presentedat the InternationalConferenceon Infant infants' object categorization . Studies , Miami, Florida, May 1992 's useof . Preschooler relationsin classifica Waxman , S.R. and R. Gelman, 1986 superordinate tion. CognitiveDevelopmentI , 139- 156.

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Waxman . Nounshighiijbt categoryrelationsin 13-month-old infants. , S.R. and L. Helm, 1991 Posterpresented at the Societyfor Research in Child Development . , Seattle , WA, April 1991 Waxman . Nouns mark categoryrelations: Toddlers' and , S.R. and T.O. Kosowski, 1990 ' - 1473 . Child Development 61, 1461 . preschoolersword-learningblases Waxman 1990 . Relations word , S.R. and A. Senghas , among meaningsin early lexicaldevelopment . Paperpresented at the InternationalConference for InfancyStudies , Montreal, Canada , . April 1990 Woodward . The role of the whole object assumptionin early word learning. , A. L., 1992 , StanfordUniversity, Stanford, CA. Unpublisheddoctoraldissertation Woodward . Constraintson learningas default assumptions : , A.L. and E.M. Markman, 1991 ' s ' The mutual ' Commentson Merriman & Bowman exclusivitybias in childrens word ' Review14, 57- 77. learning. Developmental

) 229- 257. North-Holland Lingua92 ( 1994

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Thedevelopment of an appreciation of specificlinkagesbetween linguisticand * organization conceptual Sandra R. Waxman Road. Evanston . Northwestern . 2029Sheridan . 1L 60208 , USA Department of Psychology University Evidencefrom infants and toddlers, and from preschoolchildren learningeither English, French, or Spanishas their first languageare summarizedto revealthe emergence of specific . The data suggestthat infantsbeginthe linkagesbetweenlinguisticand conceptualdevelopment processof word learningwith a generalexpectationthat words (independentof the linguistic form) referto objectsand objectcategories . This initial, rudimentarylinkagegivesway to more ) and particular specificpairingsbetweenparticular linguisticforms (e.g., nounsvs. adjectives ). Thesemorespecificlinkages typesof meaning(e.g., objectcategoriesvs. propertiesof objects . maydependupon languageexperience

. ' 'WhenI makea word do a lot of work like that I , alwayspay it extra (LewisCarroll 1895 ) I . Introduction Humans are uniquely endowed with the capacity to build complex , flexible , ' ' and creative linguistic and conceptual systems. Infants and toddlers remarkable achievements in each of these arenas have engaged researchers for decades. Yet in recent years , it is the relation between linguistic and conceptual development that has come to occupy center stage. Some of the most exciting current work has been designed to explore the relation between early ' linguistic and conceptual development in the young child s acquisition of the lexicon . This new , integrative approach has brought into sharp focus a fascinating puzzle . We know that infants acquire their native language naturally at a . This work wassupportedin part by grant # HD30410from NIH . Thanksto Marie Balaban , D. GeoffreyHall, ElizabethShipley , and an anonymousreviewerfor their commentson a previousversion. - 3841/94/ $07.00 ~ 1994- ElsevierScienceB.V. All rightsreserved 0024 SSDI0024- 3841( 93) EO041- S

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remarkable pace (Carey 1978, Dromi 1987, Gopnik and Meltzoff 1987, Nelson 1983) . We also know that even before learning the words to express them, infants appreciate many different kinds of conceptual relations among objects, including category relations, thematic relations, causal relations, and event-related or associative groupings (Bornstein 1984, Leslie and Keeble 1987, Mandler et al. 1987, Younger and Cohen 1986) . These early linguistic and conceptual achievementsset the stagefor what has beendescribedas ' the inductive problem of word learning' (Goodman 1983, Quine 1960, Carey 1990). The problem is that , in principle, the richnessand flexibility of infants' conceptual abilities should complicate the task of mapping new words to their meanings. To understand why this is the case, consider a typical word learning scenario, in which an adult introduces a child to a novel object (say, a ' ' flamingo) and offers a novel label ( a flamingo ) . Let us assumethat both the child and adult are focusing attention on the same object or scene( Baldwin and Markman 1989, Tomasello 1988) . If children have the conceptual ability to appreciateso many different kinds of relations involving that object, and if ' each of these is a potential candidate for the new word s meaning, then how do infants select from among these many possible meanings when determining what the new word is intended to convey? How do infants so rapidly learn that a given word (e.g., flamingo) may apply to a particular whole object and may be extended to other members of that object category (e.g., other flamingos)~but not to salient properties of the object (e.g., its long neck or unusual color), to salient actions in which it is engaged(e.g., feeding its young), or to salient thematic relations (e.g., a flamingo and sand) ? If children had to rule out theseand countlessother logically possiblecandidate meanings, word learning would be a formidable task indeed.

1.1. Solvingthe inductiveproblem Yet despite the logical difficulty of the task, young children rapidly and success fully map novel words and meanings. This observation has led several researchers , working from several different paradigms, to suggestthat children come to the task of word learning equipped with certain implicit blases or expectationswhich lead them to favor some types of conceptual relations over others when ascribing meaning to a new word (Chomsky 1986, Landau and Gleitman 1985, Pinker 1984, Markman 1989, Waxman 1990, 1991) . The claim is that these expectations reduce the logical difficulty of word learning

S.R. Waxman I Linguistic and conceptualorganization

by narrowing the range of candidate meanings a child will consider for any given new word. Several such implicit blaseshave been proposed. For example, researchin several different laboratories has converged on the finding that children expect that the first word applied to a novel object will refer to the whole object and other members of its basic-level kind , rather than to its parts or other salient aspects(Markman and Wachtel 1988, Taylor and Gelman 1988, Hall et al. 1993, Markman 1989) . Further evidencerevealsthat children, like adults, expect that different words will contrast in meaning (Clark 1987, Golinkoff et al. 1992, Markman 1984, 1989; Merriman and Bowman 1989, Waxman and Senghas1992). A third type of bias or predisposition will serve as the focal point of this article. There is now considerableevidencethat children use the grammatical form of a novel word (e.g., count noun, proper noun, adjective) as a guide to determining its meaning (Brown 1957, Katz et al. 1974, Landau and Gleit man 1985, Naigles 1990, Gleitman et al. 1987, Hall and Waxman 1993) . For example, by two to three years of age, English-speaking children expect objects and object categories(e.g., flamingos, birds, animals) to be marked by count nouns (Markman and Hutchinson 1984, Waxman and Gelman 1986, Waxman and Kosowski 1990, Waxman and Hall 1993) ; they expect substances (e.g., wood ; gel) to be marked by mass nouns (Dickinson 1988, Sola et al. 1991); and they expect object properties (e.g., size, color ) to be marked by modifiers (Gelman and Markman 1985, Hall et al. 1993, Taylor and Gelman 1988, Waxman 1990) . Notice that any linkage between grammatical form class and meaning requires that the word learner has (a) the linguistic capacity to distinguish among the relevant syntactic categories (e.g., count noun vs. mass noun vs. adjective) in her language, and (b) the conceptual or perceptual ability to appreciate the various kinds of relations among objects. In sum, recent work has establishedthat young children appreciatelinkages between particular types of words (e.g., count nouns vs.. adjectives) and particular types of conceptual relations. These linkages help to explain how children so rapidly map novel words appropriately to their meanings. For , although children appreciatemyriad kinds of conceptual relations, only some of these relations become lexicalized. Children do not sample randomly among thesemany possible relations when determining the meaning of a new word. Instead, particular kinds of conceptual relations are favored in the context of learning particular kinds of words.

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1.2. Overview of the article

In this article, I take as a starting point the general hypothesis that (a) young children are sensitiveto preciserelations linking linguistic with conceptual development, and that (b) these linkages promote rapid lexical acquisition and foster the establishmentof powerful systemsof conceptual organization . I begin by reviewing the evidence in support of this position with preschool-aged children, focusing primarily on the role of linguistic information ' (e.g., count nouns vs. adjectives) in the young child s ability to form categories of object kinds at various hierarchical levels (e.g. flamingo, bird , animal) . Seefigure I . Next , I turn to theoretical questions concerning the origin or developmental status of these linkages between word learning and conceptual organization, asking how and when they emerge in the developing child , This discussion highlights some limitations in the existing literature and underscores the importance of two distinct , but complementary research approaches. First , becauseso much of the existing literature is devoted to primarily preschool children who have already made significant linguistic advances, we are left with a very limited understanding of how the child acquires these important linkages early in development. Therefore, the goal of the first approach is to chart the emergenceof these links in preverbal infants and in toddlers by examining the influence of language on their categorization abilities. Second, becausethe existing researchhas been basedalmost exclusively on English-speaking subjects, it is unclear whether these linkages are universal features of human development or specific to English. Therefore, the goal of the secondapproach is to seekevidencefor theselinkages in children learning languagesother than English. Although these developmental and cross-linguistic research programs are still very much in progress, our initial results converge to suggest that the linkage between count nouns and object categories is evident even at the onset of language acquisition and may be a universal phenomenon. In contrast, the data suggesta very different developent course for the linkage between adjectives and properties of objects. This linkage appears to emerge later in development and to vary across languages.

S.R. WaxmanI Linguisticandconceptual organization

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2. Describing the phenomenon: The influence of linguistic form class infor mation on object categorization in preschool children

An essential task in early development is to form categories that capture the commonalities among objects and to learn words that describe these categories. A considerableamount of scholarly attention has been devoted to examining the establishment of categories within hierarchical systems of organization. Hierarchical systems are exceptional for their efficiency in organizing existing information and for their power in generating new information ; it therefore stands to reason that developmentalistswould seek to understand when such systemsare available to the young child. Empirical work with both adults and children has singled out one particular hierarchical level - referred to as the basic level - as being most salient psychologicalliy (Rosch et ale 1976) . The basic level, which occupies a midlevel position within a hierarchy, has been shown to have a privileged status on a range of psychological tasks. (See Rosch et ale 1976 for details.) Although it has been difficult to account formally for this privileged psychological status, the construct of a basic level has proven useful as a summary description or heuristic in research with adults and children alike (cf., Gleitman et ale 1987) . Although Mandler and her colleagues have argued against this position in favor of the view that infants initially conceptualize object~ at a level more abstract than the basic level (Mandler 1988, Mandler and Bauer 1988, Mandler et ale 1991), the weight of the evidence overwhelming favors the developmental primacy of the basic level. For example, one of the most robust findings in the developmental literature is that preschool children succeedin classifying and labeling objects at the basic level long before they do so at other hierarchical levels (Anglin 1977, Brown 1958, Mervis 1987, Mervis and Crisafi 1982, Rosch et al. 1976) . However, because the inductive and organizational power of hier