Linking language and categorization in infancy

BROCK FERGUSON AND SANDRA WAXMAN

Northwestern University

(Received June ndashRevised August ndashAccepted September )

ABSTRACT

Language exerts a powerful influence on our concepts We reviewevidence documenting the developmental origins of a precocious linkbetween language and object categories in very young infants Thiscollection of studies documents a cascading process in which earlylinks between language and cognition provide the foundation for latermore precise ones We propose that early in life language promotescategorization at least in part through its status as a socialcommunicative signal But over the first year infants home in on thereferential power of language and by their second year begin teasingapart distinct kinds of names (eg nouns adjectives) and their relationto distinct kinds of concepts (eg object categories properties) Tocomplement this proposal we also relate this evidence to severalalternative accounts of languagersquos effect on categorization appealing tosimilarity (lsquolabels-as-featuresrsquo) familiarity (lsquoauditory overshadowingrsquo)and communicative biases (lsquonatural pedagogyrsquo)

INTRODUCTION

The power of human language comes from its links to our conceptualsystems In acquiring language we acquire a means of encoding perceptualinput as objects of thought (Fausey amp Boroditsky Frank EverettFedorenko amp Gibson Gleitman amp Papafragou WinawerWitthoft Frank Wu Wade amp Boroditsky ) and a means ofcombining elemental concepts to form more complex ones (Chomsky Condry amp Spelke Murphy ) Language is also the

[] This research was supported by a Social Sciences and Humanities Research Council ofCanada Doctoral Fellowship awarded to BF and a grant from the National Institutes ofHealth (RHD) to SW The content is solely the responsibility of the authorsand does not necessarily represent the official views of the National Institutes of HealthWe are grateful to the Project on Child Development at Northwestern University andespecially to all of the parents and children who have participated in our projects Addressfor correspondence Sandra Waxman Psychology Department Northwestern University Sheridan Rd Evanston IL USA e-mail s-waxmannorthwesternedu

J Child Lang Page of copy Cambridge University Press doiS

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bedrock of cultural transmission providing an exceptionally powerful andefficient channel for sharing our thoughts and beliefs with others(Anggoro Waxman amp Medin Pinker amp Jackendoff Tomasello Vygotsky Waxman b) Although research inphilosophy and psychology makes it quite clear that there are distinctionsbetween language and thought they are often so deeply intertwined in ourexperience of the world that they seem inseparable (Gleitman ampPapafragou Pinker ) It is unsurprising then that some of themost compelling and enduring questions in the developmental andcognitive sciences have focused on identifying the links between languageand thought and how these are shaped over development (Gentner ampGoldin-Meadow Waxman b )

Over a half century of research has unearthed at least one striking linkbetween language and one fundamental conceptual process objectcategorization Studies of this link reveal that ways in which objects arenamed guides learnersrsquo organization of these objects into mental categoriesWhen the same noun is applied consistently to a set of distinct objectsboth infants and adults alike are more likely to represent them as membersof the same object category (Gelman amp Heyman Keates amp Graham Lupyan Lupyan Rakison amp McClelland Waxmanb Waxman amp Booth Waxman amp Hall Waxman ampMarkow ) Conversely hearing different nouns applied to a set ofdistinct objects draws learnersrsquo attention to distinctions among objectsfacilitating their representations as distinct individuals or distinctcategories (Dewar amp Xu Feigenson amp Halberda Ferguson Havy amp Waxman Keates amp Graham Landau ampShipley Scott amp Monesson Waxman amp Braun Xu Xu Cote amp Baker Zosh amp Feigenson )

Categorization is a fundamental building block of cognition (Mandler ampMcDonough Mareschal amp Quinn Mervis amp Rosch Murphy Sloman Malt amp Fridman Smith amp Medin )and thus this evidence documenting the power of naming oncategorization has garnered considerable attention (eg Diesendruck Gershkoff-Stowe Thal Smith amp Namy Lupyan et al Plunkett Sloutsky amp Fisher Waxman amp Gelman )When we identify two objects as members of the same category weestablish their equivalence permitting us to identify new members of thecategory and to make inferences about non-obvious properties from onemember of the category to another (Bhatt Wasserman amp Reynolds Murphy Smith amp Heise ) This seemingly simple feat hastremendous consequences on subsequent learning for example byestablishing the category DOG we can learn from just one negativeencounter to avoid all angry dogs (even ones we have not yet seen) instead

FERGUSON AND WAXMAN

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of painfully and repeatedly learning from encounters in which eachindividual dog bares its teeth

Categorization is also fundamental to word learning To successfully learnthe meaning of a novel word infants and young children must map aphonological representation to the identifiable category or referent towhich it refers In other words they must understand that the referent ofa novel noun like fridge applies not only to the appliance in their ownkitchen but also in othersrsquo Recent research suggests that infants haveestablished such mappings that is they extend even their earliest wordsbeyond named exemplars to other members of the same object category(Bergelson amp Swingley Tincoff amp Jusczyk ) Most of infantsrsquoearly words are nouns and most of these extend beyond distinctindividuals (eg ldquoMagicrdquo) to categories (doggie) Moreover infantsrsquo abilityto map nouns to object categories serves as a stepping-stone for theacquisition of other kinds of words including verbs and adjectivesbecause the meanings of these predicates are informed by the nouns thatthey take as arguments (Fisher Gertner Scott amp Yuan Gleitman Klibanoff amp Waxman Waxman amp Lidz ) From thisperspective then infantsrsquo and young childrenrsquos early links betweenlanguage and object categories serve as an engine that catalyzes subsequentlanguage and conceptual development

Our goal in this paper is to summarize the evidence documenting theemergence of a link between naming and object categorization and how itis shaped in the first few years of life We begin by describing afoundational study one that demonstrates the power of naming on objectcategorization at months of age We then look ahead in developmentpointing to evidence documenting that toddlers increasingly refine thislink over the second year of life as they cull distinct lsquokindsrsquo of words inthe input (eg nouns adjectives verbs) and link each to a distinct lsquokindrsquoof referent (eg categories of objects properties of objects categories ofevents or relations) Next we set our sights in a different directionlooking back in development to identify the origin of infantsrsquo linksbetween language and categorization in the first year of life

This review ndash looking forward and backward in developmental time ndashreveals a cascading process in which infantsrsquo earliest languagendashcognitionlinks provide the foundation for later ones To foreshadow we proposethat the power of language on cognition is initially grounded in its statusas a social communicative signal Within the first year infants home in onits referential status and in the second year they begin to tease apart thedistinct kinds of words (eg nouns verbs adjectives) and link them todistinct kinds of reference

We also discuss several alternative theoretical proposals Some haveattributed the link between language and cognition entirely to lower-level

LINKING LANGUAGE AND CATEGORIZATION

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perceptual processes On one view lsquolabels-as-featuresrsquo words promoteobject categorization simply because infants associate the words that co-occur with objects as perceptual lsquofeaturesrsquo of the objects themselves (Dengamp Sloutsky Sloutsky Sloutsky amp Fisher ) On this viewbecause objects from the same category tend to co-occur with the samelabels naming (like any shared perceptual feature) increases the similarityamong named objects and in this way promotes object categorizationHowever as will become clear as our review unfolds this view cannotaccount for the evidence First there is strong evidence that when namesare paired systematically with objects they consistently promotecategorization but that when other engaging sounds (eg tone sequencesbackward speech) are paired systematically with objects they engender nosuch boost to infantsrsquo categorization Second this view cannotaccommodate the fact that within the second year of life different kindsof words highlight different kinds of commonalities among objects Thelabels-as-features view has no account for why at this juncture nounshighlight category-based commonalities but adjectives highlight property-based commonalities including color and texture

Another low-level account focused on processing lsquoauditoryovershadowingrsquo argues that the gap between language and other non-linguistic sounds can be reduced to an effect of auditory familiarity Herethe claim is that because infants are more familiar with the sounds ofspeech than with other non-linguistic sounds (Robinson amp Sloutsky b Robinson Best Deng amp Sloutsky Sloutsky ampRobinson ) and because it is less costly to process familiar thannovel stimuli non-linguistic sounds can lsquoovershadowrsquo infantsrsquo ability toprocess materials simultaneously presented in the visual modality (see alsoLewkowicz a b) Therefore although language appears topromote object categorization it may in fact be merely less disruptive thanthe other less familiar sounds While this account can capture somedifferences between linguistic and non-linguistic sounds like the labels-as-features above it is stretched to explain why different kinds of language (eg nouns adjectives) which differ in meaning ndash but critically not inacoustic familiarity ndash have different conceptual consequences or why aswe will discuss a select group of unfamiliar signals also promotescategorization early in infancy

Another relevant theory lsquonatural pedagogyrsquo is closer in spirit to our ownposition but still differs considerably especially with regard to thedevelopmental processes underlying the link between language andcategorization in the first two years of life Natural pedagogy asserts thatthe power of language comes at least in part from its socialcommunicative status and we agree But natural pedagogy also claims thatother communicative signals (eg eye-gaze pointing) are on par with

FERGUSON AND WAXMAN

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language vis-agrave-vis their effects on cognition (Csibra amp Gergely Csibra amp Shamsudheen Futoacute Teacuteglaacutes Csibra amp Gergely Hernik amp Csibra Marno Davelaar amp Csibra YoonJohnson amp Csibra ) that human infants are born with an expectationthat information conveyed by a pedagogical partner (eg a parent) viaostensive communicative signals is lsquokind-relevantrsquo and that as a resultcommunicative signals (including but not limited to language) biasinfants toward establishing categories of object kinds We agree that infantcognition is guided by the social communicative status of language in thefirst year Where we differ is in our view of the function of language asprimarily kind-relevant and in our view of developmental processesunderlying language over the course of this first year In our viewlanguage lsquoparts companyrsquo from the other communicative signals in the firstyear as infants pinpoint with increasing precision the range of meaningthat can be conveyed with language

We discuss these alternative accounts at various junctures in this review asevidence relevant to each account is introduced

LINKING LANGUAGE AND CATEGORIZATION ndash A FOUNDATIONAL

STUDY

Waxman and Markow () offered the first evidence of a link betweenlanguage and object categorization in infants who were on the verge ofproducing their first words They recruited -month-old infants toparticipate in a classic categorization task one that included afamiliarization phase and a test phase (see Figure ) Duringfamiliarization infants were shown several members of a category (egANIMAL) each accompanied by a phrase What varied was the particularphrase infants heard Infants in a Word condition heard a novel nounapplied to each object (eg ldquoLook This is a blick Do you see theblickrdquo) those in a No Word control condition heard phrases that drewtheir attention to the objects but included no novel words (eg ldquoLookwhatrsquos here Do you like itrdquo) At test infants viewed two novel objectssimultaneously One was a novel member of the now-familiar category(eg a new animal) and the other a member of a new object category towhich infants had not yet been exposed (eg a piece of fruit)

This design took advantage of decades of research in infant cognition(Colombo amp Bundy Eimas amp Quinn Fantz Spelke ampKestenbaum ) documenting that if infants notice the commonalityamong the objects presented during familiarization then they show apreference for the novel over the familiar test object and that converselyinfants who fail to detect this category during familiarization show nopreference at test

LINKING LANGUAGE AND CATEGORIZATION

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Building on this logic Waxman and Markow () manipulated thedesign to consider the contribution of naming They reasoned that ifnovel nouns support object categorization in infants as young as

months then infants in the Word condition should more successfully formcategories than those not hearing novel words (No Word condition) Theirresults supported this prediction documenting that by months of ageinfants have begun to establish a link between object naming and objectcategorization (for further evidence at months see Ferguson Havy ampWaxman Fulkerson amp Haaf Waxman amp Braun )

Balaban and Waxman () provided additional evidence for the power oflanguage in slightly younger infants They compared the effect of novelwords versus tone sequences on -month-oldsrsquo categorization Once againinfants in a Word condition heard a naming phrase accompanying eachfamiliarization object But infants in a Tones condition heard a sequenceof sine-wave tones accompanying each object These tone sequences werecarefully matched to match the Word condition in mean frequencyduration and pause length They reasoned that if any consistently appliedsound promotes -month-oldsrsquo object categorization then infants in bothof these conditions should succeed in forming the category however iflanguage exerts a unique effect on categorization as early as months theninfants in the Word condition but not the Tones condition should succeedThe results were clear infants in the Word condition successfully formedcategories but those in the Tones condition performed at chance levelThis documented an advantage for novel words over carefully matchednon-linguistic control stimuli in infants as young as months of age

Together these studies provided evidence that the link between languageand categories is established early and that it is not built up from

Fig A representation of stimuli and results from Waxman and Markow () andBalaban and Waxman ()

FERGUSON AND WAXMAN

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associations between words in infantsrsquo existing vocabulary (Smith )After all infants at and months of age produce only a few if anywords on their own Instead the data reveal that a link between languageand object categories is not the result of lexical development but insteadis in place early enough to support infantsrsquo vocabulary development fromthe start

Notice that neither the labels-as-features nor the auditory overshadowingaccounts can account for both of these results on their own The labels-as-features account best explains Waxman and Markowrsquos () finding thatinfants who heard a count noun consistently applied to a set of objectsmore reliably categorize them than do infants in a No Word condition Onthe labels-as-features account for infants in the Word (but not the NoWord) condition the shared novel noun increases the similarity among thefamiliarization objects and thereby supports categorization Infants in theNo Word condition did not benefit from this increased similarity andtherefore failed to form the categories But this account cannotaccommodate Balaban and Waxmanrsquos () finding that novel tonesequences ndash which were also applied consistently to all familiarizationobjects ndash failed to exert this advantageous effect If any consistently pairedauditory lsquofeaturersquo account can increase the similarity of the objects withwhich it is paired then both words and tones should exert the sameinfluence

On the other hand auditory overshadowing can explain Balaban andWaxmanrsquos () finding but not Waxman and Markowrsquos () In thecase of Balaban and Waxman () auditory overshadowing wouldsuggest that infants hearing language (but not tones) formed objectcategories because the tone sequences were less familiar than language Butthe auditory overshadowing account cannot explain why certain kinds oflanguage (eg ldquoLook at the tomardquo) facilitate categorization while otherkinds of language (eg ldquoLook at thisrdquo) fail to do so In short each of thesealternative proposals can accommodate one set of findings but neither canexplain both

These results also bear on the proposal concerning lsquonatural pedagogyrsquo(Csibra amp Gergely ) In Waxman and Markow () all infantswere introduced to the familiarization objects in conjunction with humanspeech ndash a pedagogical cue Although infants in the Word condition(ldquoLook at the tomardquo) successfully formed object categories those in theNo Word condition (ldquoLook at thisrdquo) did not This reveals that by

months infants have precise expectations about the functions of languagenovel nouns but not any referring phrase refer to object categories Thusinfants do not interpret all communicative signals as kind-relevant (cfCsibra amp Gergely ) rather by their first birthdays when infantsbegin to build their own productive lexicons they have distinguished

LINKING LANGUAGE AND CATEGORIZATION

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naming from other functions of language and link object naming alone toobject categorization

This evidence from - to -month-old infants although impressive alsoraised new developmental questions When do infants establish more preciselinks mapping certain kinds of words (eg nouns) to object categories butother kinds of words (eg adjectives verbs) to different kinds of meaning(eg object properties event categories)

SPECIFYING THE LINK A LOOK FORWARD IN DEVELOPMENT

The links between language and categorization expressed in -month-oldsdo not remain constant across development On the contrary infantsrsquoexpectations about naming become increasingly precise during theirsecond year During this time infants tease apart the nouns from theother grammatical forms (eg adjectives verbs) and map them specificallyto object categories rather than surface properties (like color) or actions inwhich they are involved (like running) Consider for example a scene inwhich a group of horses jumps over a fence Infants in the second year oflife focus on different aspects of this scene depending upon how it isdescribed So do older children and adults For example nouns (egldquoLook Theyrsquore horsesrdquo) focus our attention on the object category Butverbs (eg ldquoLook Theyrsquore runningrdquo) direct our attention to the actionand adjectives (eg ldquoLook Theyrsquore whiterdquo) refer neither to the objects orevent but to a property of the objects We know that even infants can usethe position of a word within a sentence to distinguish among grammaticalcategories (Hall Veltkamp amp Turkel Houmlhle Weissenborn Kiefer ampSchulz Mintz Shi Waxman amp Lidz Weislederamp Waxman ) and by to months they forge increasingly preciselinks between distinct grammatical forms and their distinct kinds ofmeaning They link nouns to object categories verbs to actions andrelations among objects and adjectives to object properties

These more specific links between distinct kinds of words and distinct kindsof meaning unfold in a cascading fashion (see Waxman amp Lidz for acomprehensive review) First by months infants tease apart the nounsfrom other grammatical categories and link them specifically to objectcategories Next with this nounndashobject category link in place they go on toforge the more precise links for predicates including adjectives and verbswhose meaning depends in part upon the nouns they take as arguments

Until roughly months of age infants appear to be lsquogeneralistsrsquo when itcomes to linking words and concept Novel words be they presented asnouns or adjectives highlight any kind of commonality among objects(eg category-based or property-based commonalities) (Waxman bWaxman amp Booth Waxman amp Markow ) A clear

FERGUSON AND WAXMAN

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demonstration of this can be found in a study by Waxman and Booth ()in which they presented -month-old infants with a set of four objects (eg different purple horses) that shared both a category-based (horse) andproperty-based (purple) commonality (see Figure ) At issue was whetherinfants focused on categories or properties and whether their focus wasshaped by the language they heard as they viewed these objects (Waxmanamp Booth ) To assess this infants participated in either a lsquopropertyrsquoextension test (eg pitting a new purple horse against a new green horse) ora lsquocategoryrsquo extension test (eg pitting a new purple horse against a newpurple chair) They reasoned as follows if infants expect that differentkinds of words refer to different kinds of meaning then their performancein the Noun and Adjective conditions should differ More specifically ifthey map nouns to object categories and adjectives to object propertiesthen () infants for whom the familiarization objects were introduced witha novel noun should successfully extend the noun to another horse but notto other objects sharing only color but not category membership and ()infants who were introduced to novel adjectives should successfully extendthem to the object property but not the category Demonstrating theinfantsrsquo status as generalists at this age Waxman and Booth () foundthat -month-olds who heard either kind of novel word (either nouns oradjectives) focused on either kind of commonality (category- or property-based) they extended the novel word either by property or by categorydepending on their test condition In contrast -month-olds in a NoWord condition (ldquoCan you give me that onerdquo) performed at chance

But infants do not remain generalists for long By months they haveteased apart the nouns in the input and have begun to link themspecifically to object categories but not object properties In other wordsin the categorization task described above -month-olds extend novelnouns on the basis of category-based but not property-basedcommonalities (Waxman a) Nevertheless -month-olds have notyet acquired a comparably precise expectation for adjectives Instead formost of their second year infants continue to link novel adjectives toeither category-based (eg horse) or property-based (eg color texture)commonalities (Booth amp Waxman Imai amp Gentner Waxmana Waxman amp Booth ) only later do they begin mapping noveladjectives specifically to property-based and not category-basedcommonalities (Waxman amp Markow ) Moreover infantsrsquoexpectations for novel verbs appear to follow an even more protracteddevelopmental course only by months do infants reliably map novelverbs to event categories rather than object categories (Arunachalam ampWaxman Arunachalam Escovar Hansen amp Waxman SyrettArunachalam amp Waxman Tomasello amp Kruger WaxmanLidz Braun amp Lavin Yuan amp Fisher )

LINKING LANGUAGE AND CATEGORIZATION

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By tracing infantsrsquo expectations for novel words through the second year oflife a developmental cascade becomes evident one in which infants discoverthat there are distinct kinds of words and that each refers to a distinct kind ofmeaning This cascade in which precise expectations for nouns paves theway for expectations for predicate forms poses challenges for accounts thatappeal to perception alone

The labels-as-features perspective asserts that words are nothing morethan perceptual features of the objects to which they are applied If thiswere correct then it is puzzling that novel nouns highlight category-based(but not property-based) commonalities among objects at months(Waxman a Waxman amp Booth ) This outcome reveals thatlabels do more than simply increase the perceived similarity amongobjects otherwise novel nouns should highlight both category- andproperty-based commonalities equally

Arguments for auditory overshadowing fare no better in accounting forthis developmental cascade After all infants in the Noun Adjective andVerb conditions in these various experiments were all listening to speechIn fact they heard the very same novel wordforms paired with the verysame sets of objects thus infantsrsquo familiarity with the wordforms and theobjects are held constant across conditions and experiments The onlything that varied was the grammatical context in which a novel word ndash thesame novel word ndash appeared Infantsrsquo distinct responses to different kindsof words in these experiments reveal the insufficiency of an auditoryovershadowing account Infantsrsquo performance is mediated by more thanthe lsquofamiliarityrsquo of speech they are also sensitive to distinctions amongdistinct kinds of words and the concepts to which they refer

Finally these findings also reveal shortcomings in the predictions ofnatural pedagogy highlighting that this proposal requires greater

Fig A representation of stimuli and results from Booth and Waxman () Waxman() and Waxman and Booth ()

FERGUSON AND WAXMAN

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precision Communicative signals of all kinds ndash including language eye-gaze and pointing ndash can highlight either objects and events (Liszkowski ampCarpenter Namy amp Waxman Peirce ) But onlylanguage can single out which of the myriad possible commonalitiespresent within a particular set of entities a speaker is referring to Forinfants as young as months of age language does more than highlightobject categories or kinds By this point infants use the grammatical formof a novel word to shift their perspective on the scene at hand

THE ORIGINS OF THE LINK LOOKING BACK INTO INFANTS rsquo FIRST

YEAR OF LIFE

In more recent work in our lab we have shifted our focus to looking back indevelopmental time Our goal is to uncover the origin of infantsrsquo earliestlinks between language and cognition and to trace how this link unfoldsin the infantsrsquo first year

As a first step in this direction Fulkerson and Waxman () adaptedBalaban and Waxmanrsquos () categorization task to examine the effect oflanguage on categorization in -month-old infants (see Figure ) In thefamiliarization phase infants viewed eight images from a single category(eg dinosaurs) one at a time in random order on a screen What variedwas the auditory input accompanying each image Infants either heard anovel word (eg ldquoLook at the modi Do you see the modirdquo) or thesequence of sine-wave tones At test infants viewed two new imagespresented in silence ndash a new member of the familiar category (eg anotherdinosaur) and an object from a novel category (eg a fish) Infants wholistened to language during familiarization formed object categories aswitnessed by their reliable preference for the novel object at test Incontrast infants who listened to tone sequences performed at chancelevels Thus at months when infants are just beginning to comprehendtheir first words (Bergelson amp Swingley Tincoff ampJusczyk ) they have already begun to link language and objectcategories

Armed with this evidence Ferry Hespos and Waxman () consideredstill younger infants extending this task to - and -month-olds The resultswere surprising and revealed an advantage for language over tones vis-agrave-viscategorization even in these very young infants although - and -month-olds listening to language successfully formed object categories thoselistening to sine-wave tone sequences performed at chance levels just likeat and months (Fulkerson amp Waxman )

These results reveal strong developmental continuity in infantsrsquo responseto language versus tones in the first year of life They also illuminate asurprisingly precocious link between language and categorization one that

LINKING LANGUAGE AND CATEGORIZATION

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is in place early enough to support infantsrsquo very first forays in language andcognitive development But why does listening to human language lsquoboostrsquoinfant cognition so early in development It is unlikely that -month-oldinfants understand the meanings of any words (Fenson et al FrankBraginsky amp Yurovsky ) Indeed there is little evidence that they caneven parse individuals words from the ongoing stream of language (Aslin Bortfeld Morgan Golinkoff amp Rathbun Jusczyk amp Aslin Seidl Tincoff Baker amp Cristia ) What is it then thatunderlies the cognitive advantage conferred by language at and

months It must be different than at months because Waxman andMarkowrsquos () study clearly demonstrated that by monthsidentifying a novel word in the speech stream is critical (recall that infantsformed object categories when they heard a novel noun consistentlyapplied to the familiarization objects but not when they heard the samekinds of phrases with no novel word (eg ldquoLook at thisrdquo) If - and-month-olds do not yet parse distinct words from the continuous streamof speech then what is the mechanism by which language confers itsadvantage

Ferry et al () proposed that for - and -month-olds simplylistening to language might promote object categorization Previous studieshave shown that infants prefer listening to human speech over other non-speech sounds (Shultz amp Vouloumanos Vouloumanos HauserWerker amp Martin ) Of course a preference for speech cannot explainwhy infants link speech to their construal of the world (that is the objectsthey view in our tasks) Perhaps listening to speech not only engagesinfantsrsquo attention but also promotes their learning One intriguing aspect

Fig A representation of stimuli and results from Balaban and Waxman () Ferryet al ( ) and Fulkerson and Waxman ()

FERGUSON AND WAXMAN

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of the studies on infantsrsquo preferences for language is that early on infantsprefer both human speech and non-human primate vocalizations overother sounds suggesting that they tune their preferences to human speechover the first months of life (Shultz Vouloumanos Bennett amp Pelphrey Vouloumanos amp Werker ) Might non-human primatevocalizations also promote - and -month-olds object categorization

To address this possibility Ferry Hespos and Waxman () examinedthe effect of listening to two new sounds ndash non-human primate vocalizationsand backward speech ndash on infantsrsquo object categorization at - - and-months The design was identical to the studies by Fulkerson andWaxman () and Ferry et al () what varied were the soundsinfants listened to during the familiarization period For half of theinfants the familiarization images were accompanied by a vocalizationfrom a blue-eyed Madagascar lemur (Eulemur macaco flavifrons) for theothers the images were accompanied by a segment of backward speech(the language stimuli from prior experiments played in reverse) If theinitial link between language and cognition like infantsrsquo initial preferencesencompasses human speech and non-human primate vocalizations then- and -month-olds listening to lemur vocalizations should successfullyform object categories Alternatively if any complex sound promotesobject categorization at this young age then infants listening to eitherlemur vocalizations or backward speech should successfully form categories

These results of this study testing the breadth of sounds that promote -and -month-oldsrsquo categorization were clear Infants listening to backwardspeech failed to form categories at any age echoing the results with sine-wave tone sequences at the same ages as in Ferry et al () andFulkerson and Waxman () with a more complex auditory signal Incontrast the lemur vocalizations conferred the same cognitive advantage aslistening to human language - and -month-olds in the lemur conditionsuccessfully formed object categories performing identically at test asinfants in Fulkerson and Waxmanrsquos () study with human speech Yetthis effect was short-lived by months infants had tuned the linkspecifically to language At months lemur vocalizations no longerconferred infants any benefit in categorization (Ferry et al )This work offers two insights into the origins of infantsrsquo earliest links

between language and cognition First at and months the link issufficiently broad to encompass vocalizations of both humans and non-human primates Second by months infants tune this initially broadlink to the signal that will ultimately carry meaning human speech

These results also posed new challenges to alternative accounts for the linkbetween language and cognition in infancy First the auditory overshadowingaccount cannot accommodate the facilitative effect of lemur vocalizations on- and -month-oldsrsquo object categorization Lemur calls are certainly

LINKING LANGUAGE AND CATEGORIZATION

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unfamiliar to - and -month-olds yet they facilitated (rather than hindered)infantsrsquo object categorization Auditory overshadowing also fails to accountfor the finding that infants tune out the effect of lemur vocalizations by

months After all the assumption underlying the overshadowing accountrests on the processing load imposed by an unfamiliar versus familiarsignal Yet infantsrsquo exposure to lemur vocalizations likely remains sparse ndashand therefore constant ndash between and months

These results also expose limitations in the theory of natural pedagogy atheory that has not engaged key developmental questions including whichsignals very young infants identify as communicative and how thepedagogical force of these signals changes over the first years Ferry et alrsquos( ) results provide clear evidence that what counts as acommunicative signal changes with development

In subsequent work we have gone further to consider the processes thatmediate infantsrsquo interpretation signals like lemur calls and tone sequencesover the first year pinpointing the role of passive and communicativeexperience

A CLOSER LOOK HOW DO INFANTS lsquoTUNE rsquo THE LINK BETWEEN

LANGUAGE AND OBJECT CATEGORIZATION

Ferry et alrsquos () results documented the first evidence that the linkbetween language and categorization may be lsquotunedrsquo early in developmentTuning processes are ubiquitous in infant perceptual development (egface perception speech perception Krentz amp Corina Lewkowicz ampGhazanfar Maurer amp Werker Palmer Fais Golinkoff ampWerker Pascalis Loevenbruck Quinn Kandel Tanaka amp Lee Quinn Lee Pascalis amp Tanaka Scott amp Monesson Werker amp Tees ) But the results reported by Ferry et al() document more than just perceptual tuning Instead their resultswere the first to document that infants tune the lsquolinkrsquo between languageand categorization in the first months of life

With this effect as a foundation we have gone on to examine the relativecontributions of maturation and experience as infants tune this link(Perszyk Ferguson amp Waxman in press) (see Figure )

How far can experience take us Documenting the effect of lsquomere exposurersquo tonon-language sounds

In one recent line of research we asked whether and how infantsrsquo experiencecontributed to tuning this link between language and categorization Perhapsinfantsrsquo frequent exposure to human speech in their everyday environmentspermits them to maintain the link between speech and object categorization

FERGUSON AND WAXMAN

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while lsquotuning outrsquo the influence of non-human primate vocalizations whichare likely absent in their environments

One way to assess the role of experience is to manipulate it experimentallyA signature of experience-based tuning processes is the powerful role of laterexposure once infants have tuned out an earlier sensitivity this sensitivitymay be reinstated if infants are re-exposed to the signal anew during whatis known as a lsquosensitive periodrsquo (Johnson amp Newport Kuhl Tsao ampLiu Werker amp Hensch ) Might this signature of experience-based tuning be evident in the link between a signal and categorization Ifinfantsrsquo experience is essential then exposing infants to lemurvocalizations might permit them to lsquore-openrsquo the link to categorization

Perszyk and Waxman () addressed this question by systematicallymanipulating -month-old infantsrsquo exposure to lemur vocalizations Wheninfants entered the labrsquos waiting room they listened to a -minute audiotrack comprised of instrumental music (eg a Bach quartet) interspersedat irregular intervals with several distinct lemur vocalizations Thisprovided infants with a total of minutes of passive exposure to lemurvocalizations Importantly these vocalizations were not connected to anycommunicative function Next infants entered the testing room toparticipate in the same categorization task while listening to lemurvocalizations (as in Ferry et al ) If experience is instrumental intuning the link then even this brief exposure with lemur vocalizationsshould be enough for -month-olds to reinstate the earlier link betweenlemur vocalizations and object categorization

Fig A representation of stimuli and results from Ferguson and Waxman () andPerszyk and Waxman ()

LINKING LANGUAGE AND CATEGORIZATION

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This prediction was borne out In contrast to their peers provided with nosuch exposure (Ferry et al ) -month-olds who had been exposed tolemur vocalizations in the lab successfully formed object categories whilelistening to lemur vocalizations (Perszyk amp Waxman ) This identifiesinfantsrsquo flexibility and a critical role for experience in tuning the link tocognition even minutes of exposure permitted -month-olds to linklemur vocalizations to categorization Without this exposure the link hadbeen severed

But perhaps exposure to any sound ndash not only those that initially promotecategorization ndash would have been sufficient to promote infantsrsquocategorization This is the prediction of the auditory overshadowingaccount Perszyk and Waxman () provided clear evidence against thispossibility by exposing another group of infants to the same classicalmusic audio track but this time replacing the lemur vocalizations withsegments of backward speech a signal that fails to promote objectcategorization at any age (Ferry et al ) Although infantsrsquo exposureto backward speech or lemur vocalizations was identical in the twoconditions the results were quite different infants exposed to backwardspeech failed to form object categories in our task This striking contrastsuggests that exposure may be instrumental in maintaining a link betweenan auditory signal and categorization only if that signal is part of theinitially privileged set of sounds that infants previously linked tocategorization A goal of our ongoing work is to specify the range ofsignals that are initially privileged in this way

Can infants interpret otherwise arbitrary sounds as communicative The powerof embedding signals in a social-communicative exchange

In a complementary line of work we have asked about the developmentalfate of signals that fall outside the initially privileged set ndash like sine-wavetone sequences and backward speech ndash signals that infants consistently failto link to object categorization throughout their first year (Ferry et al Fulkerson amp Waxman ) As adults we can flexibly link manysignals to meaning even unnatural signals like the beeps of Morse codeBut what about infants Might there be some path by which even infantswill privilege these otherwise inert sounds to communicative status andlink them to categorization Or does this capacity come only later afterthey have established a foundational communicative system such aslanguage

We reasoned that if we embedded these sounds in communicativeepisodes then infants might interpret them as communicative At issuethough was whether by raising them to communicative status thesesignals might then (like language) promote infantsrsquo categorization Our

FERGUSON AND WAXMAN

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hypothesis was motivated by three other lines of research First myriadstudies have demonstrated that even from birth infants are drawn notonly to speech but also to other communicative stimuli For exampleinfants prefer to look at face-like stimuli over non-faces (Farroni JohnsonMenon Zulian Faraguna amp Csibra Valenza Simion amp Cassia) and to look at communicative gestures over non-communicativepantomime (Krentz amp Corina ) Second beginning around monthsinfants appear to represent the communicative function of some signals insocial interactions (Grossmann Parise amp Friederici Krehm Onishiamp Vouloumanos Lloyd-Fox Szeacuteplaki-Koumlllőd Yin amp Csibra Parise amp Csibra Vouloumanos Martin amp Onishi Vouloumanos Onishi amp Pogue ) Finally as discussed with respectto natural pedagogy a range of communicative signals beyond speech (egpointing and eye-gaze) appear to shape infantsrsquo learning at least in somecontexts Of particular interest to us given that we have been investigatingobject categorization is the claim that infants encode category-relevantproperties of novel objects more effectively in communicative contextsthan in non-communicative contexts (Csibra amp Gergely Futoacute et al Hernik amp Csibra Wu Gopnik Richardson amp Kirkham Yoon et al ) Together these lines of research raise an intriguingpossibility if infants are first introduced to the otherwise inert sound as ifit like language is a communicative signal this sound may be elevated tocommunicative status and might subsequently promote infantsrsquo objectcategorization

To address this possibility we turned our focus to sine-wave tonesequences asking whether they might in fact promote -month-oldsrsquoobject categorization if just prior to the categorization task we introducedinfants to the tones as if they were a communicative signal We created abrief (-minute) vignette depicting a dialogue between two actors One ofthe actors spoke in English and the other responded using sine-wave tonesequences This vignette clearly demonstrated that the tones served acommunicative function After viewing this vignette infants participatedin the categorization task while listening to tone sequences (Fulkerson ampWaxman ) The vignette had a remarkable impact after observingthe tone sequences embedded in a social communicative exchange-month-olds successfully categorized while listening to tones somethingwe had not yet seen in any prior study at any age (Ferguson amp Waxman) This suggests that when an otherwise inert signal is introduced inthe context of a social communicative exchange -month-old infantselevate this signal to communicative status and forge an entirely new linkbetween this signal and categorization

Moreover this effect is related specifically to communicative informationsimply familiarizing infants to the tones ndash absent any communicative

LINKING LANGUAGE AND CATEGORIZATION

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exchange ndash does not promote their use in categorization To demonstratethis we familiarized another group of infants to precisely the same tonesequences but uncoupled them from the communicative episode offeringno evidence that tones served a communicative function In this conditionwe modified the vignette so that the lsquoconversationrsquo (ie the speech andtone sounds) played in the background ndash as if the sounds were playing onthe radio ndash while the two actors engaged in a separate cooperative taskAlthough infants in this condition heard precisely the same tones forprecisely the same amount of time they failed to form the categories inthe subsequent categorization performing instead at chance levels Thiscontrast between infantsrsquo success in the communicative condition andfailure in the non-communicative control condition reveals the powerof lsquocommunicativersquo exposure alone in linking the tones to objectcategorization at months of age

This outcome provides the strongest evidence to date against auditoryovershadowing (Robinson et al Robinson amp Sloutsky b)Ferguson and Waxman () held the familiarity of the tones constantacross both conditions infants in the two conditions had the exact sameamount of exposure to the tones before the categorization task Familiarityalone therefore cannot explain why only those -month-olds exposed totones as a communicative signal later succeeded in categorizing objectswhile listening to tones

Our interpretation of the power of communicative experience in linking anotherwise inert sound (eg tones) to object categorization is consistent withthe proposal for natural pedagogy (Csibra amp Gergely ) After learningthat the tones were communicative listening to tones seems to haveengendered a communicative context that biased infants toward kind-relevant generalizable information Nevertheless this finding also revealsthat the theory of natural pedagogy (and any theory relying on infantsrsquointerpretation of communicative signals) must specify how infantslsquoidentifyrsquo which signals in their environment are communicative in thefirst place and how their interpretation of these signals is shaped overdevelopment In future research it will be important to manipulatesystematically infantsrsquo experience with an inert sound such as tones and tosubsequently assess its impact on cognition This will offer a morenuanced developmental view of how a signal becomes communicative andfrom this view lsquopedagogicalrsquo

A DEVELOPMENTAL CASCADE INFANTS rsquo EXPECTATIONS ABOUT

lsquoLANGUAGE rsquo CHANGES OVER THE FIRST MONTHS

These investigations into the origins of the link ndash its initial broad state andthe processes by which it is tuned thereafter ndash sharpen our understanding of

FERGUSON AND WAXMAN

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how an early link between language and object categorization evolves early indevelopment We propose that at and months an initially privileged setof sounds ndash encompassing human speech and non-human primatevocalizations (Ferry et al ) ndash promotes categorization bybroadly engaging infantsrsquo attention By months this link is tuned tocommunicative signals through complementary processes of passiveexposure (maintaining the links of those signals to which infants arefrequently exposed Perszyk amp Waxman ) and social-communicativeexposure (capable of privileging otherwise inert signals to communicativestatus Ferguson amp Waxman ) Later as infants approach their firstbirthday this broad effect of communicative signals begins to be refined asinfants discover which lsquokindsrsquo of language are particularly relevant tocategorization (Fennell amp Waxman Hollich Hirsh-Pasek ampGolinkoff Marcus Fernandes amp Johnson May amp Werker Namy amp Waxman Woodward amp Hoyne ) Thisdiscovery prompts a shift in attention from those signals that arelsquocommunicativersquo to the ways in which labels alone are lsquoreferentialrsquo Asinfants learn about the referential capacities of different kinds of labelslanguage becomes capable of more than broadly engaging infantsrsquoattention but also of highlighting different conceptual interpretations ofthe very same objects (Booth amp Waxman Waxman amp Booth) Only with additional evidence can we identify the mechanismsunderlying these shifts

In these ways although language promotes categorization throughout thefirst two years of life the nature of this influence evolves during this periodalong with the developing capacities of the infant Proposals that appeal onlyto infantsrsquo perceptual experience and processing of language (Robinson et al Sloutsky amp Fisher ) cannot capture this dynamic cascadingdevelopmental process Likewise although we propose that these linksbetween language and concepts are grounded in infantsrsquo representation oflanguage as a communicative signal proposals that posit an enduringstatic bias in communicative contexts (Csibra amp Gergely ) also fail tocapture this developmental trajectory While the mechanisms posited byboth of these views surely have some role to play in relating language toinfantsrsquo cognition neither appears sufficient in explaining the evidence athand

FUTURE DIRECTIONS

An important goal for future investigations is to identify which othercognitive capacities ndash in addition to object categorization ndash are shaped bylanguage in the first year of life There are reasons to suspect that languagemay cast a relatively wide facilitative net (Vouloumanos amp Waxman

LINKING LANGUAGE AND CATEGORIZATION

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) evidence has already begun to accumulate suggesting that languagepromotes other fundamental learning processes including abstract rulelearning (Ferguson amp Lew-Williams Dawson amp Gerken Marcus Fernandes amp Johnson ) and associative learning (Reeb-Sutherland Fifer Byrd Hammock Levitt amp Fox ) Identifying thebreadth of languagersquos influences ndash and the cognitive mechanisms thatundergird them ndash will provide insights into the status of infantsrsquo earliestlinks between language and cognition and how they are forged early indevelopment and will ultimately bring into sharper focus how languageand thought become entwined

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FERGUSON AND WAXMAN

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Dawson C amp Gerken L () From domain-generality to domain-sensitivity -month-olds learn an abstract repetition rule in music that -month-olds do not Cognition() ndash

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Diesendruck G () Categories for names or names for categories The interplay betweendomain-specific conceptual structure and language Language and Cognitive Processes() ndash

Eimas P D amp Quinn P C () Studies on the formation of perceptually based basic-level categories in young infants Child Development () ndash

Fantz R L () Pattern vision in newborn infants Science () ndashFarroni T Johnson M H Menon E Zulian L Faraguna D amp Csibra G ()Newbornsrsquo preference for face-relevant stimuli effects of contrast polarity Proceedings ofthe National Academy of Sciences of the United States of America () ndash

Fausey C M amp Boroditsky L () English and Spanish speakers remember causal agentsdifferently In B C Love K McRae amp V M Sloutsky (eds) Proceedings of the thAnnual Conference of the Cognitive Science Society (pp ndash) Austin TX CognitiveScience Society

Feigenson L amp Halberda J () Conceptual knowledge increases infantsrsquo memorycapacity Proceedings of the National Academy of Sciences of the United States of America() ndash

Fennell C T amp Waxman S R () What paradox Referential cues allow for infant useof phonetic detail in word learning Child Development () ndash

Fenson L Dale P S Reznick J S Thal D Bates E Hartung J amp Reilly J ()The MacArthur Communicative Development Inventories userrsquos guide and technical manualSan Diego CA Singular Publishing Group

Ferguson B Havy M ampWaxman S R () The precision of -month-old infantsrsquo linkbetween language and categorization predicts vocabulary size at and months Frontiersin Psychology online lthttpdoiorgfpsyggt

Ferguson B amp Lew-Williams C () Communicative signals support abstract rulelearning by -month-old infants Scientific Reports online lthttpdoiorgsrepgt

Ferguson B amp Waxman S R () What the [beep] Six-month-olds link novelcommunicative signals to meaning Cognition (C) ndash

Ferry A L Hespos S J amp Waxman S R () Categorization in ‐ and ‐month‐oldinfants an advantage of words over tones Child Development () ndash

Ferry A L Hespos S J amp Waxman S R () Nonhuman primate vocalizationssupport categorization in very young human infants Proceedings of the National Academyof Sciences of the United States of America () ndash

Fisher C Gertner Y Scott R M amp Yuan S () Syntactic bootstrapping WileyInterdisciplinary Reviews Cognitive Science ndash

Frank M C Braginsky M amp Yurovsky D () Wordbank an open repository fordevelopmental vocabulary data Journal of Child Language online lthttpdoiorgsgt

LINKING LANGUAGE AND CATEGORIZATION

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Frank M C Everett D L Fedorenko E amp Gibson E () Number as a cognitivetechnology evidence from Pirahatilde language and cognition Cognition () ndash

Fulkerson A L amp Haaf R A () Does object naming aid -month-oldsrsquo formation ofnovel object categories First Language () ndash

Fulkerson A L amp Waxman S R () Words (but not tones) facilitate objectcategorization evidence from - and -month-olds Cognition () ndash

Futoacute J Teacuteglaacutes E Csibra G amp Gergely G () Communicative functiondemonstration induces kind-based artifact representation in preverbal infants Cognition() ndash

Gelman S A amp Heyman G D () Carrot-eaters and creature-believers the effects oflexicalization on childrenrsquos inferences about social categories Psychological Science ()ndash

Gentner D amp Goldin-Meadow S () Whither Whorf In Language in mind advances inthe study of language and thought ndash Cambridge MA MIT Press

Gershkoff-Stowe L Thal D J Smith L B amp Namy L L () Categorization and itsdevelopmental relation to early language Child Development () ndash

Gleitman L R () The structural sources of verb meanings Language Acquisition ()ndash

Gleitman L R amp Papafragou A () Language and thought In K J Holyoak ampR G Morrison (eds) The Cambridge handbook of thinking and reasoning ndashCambridge Cambridge University Press

Grossmann T Parise E amp Friederici A D () The detection of communicative signalsdirected at the self in infant prefrontal cortex Frontiers in Human Neuroscience onlinelthttpdoiorgfnhumgt

Hall D G Veltkamp B amp Turkel W () Childrenrsquos and adultsrsquo understanding ofproper namable things First Language () ndash

Hernik M amp Csibra G () Infants learn enduring functions of novel tools from actiondemonstrations Journal of Experimental Child Psychology (C) ndash

Hollich G Hirsh-Pasek K amp Golinkoff R M () Breaking the language barrier anemergentist coalition model for the origins of word learning Monographs of the Societyfor Research in Child Development () ndash

Houmlhle B Weissenborn J Kiefer D amp Schulz A () Functional elements in infantsrsquospeech processing the role of determiners in the syntactic categorization of lexical elementsInfancy () ndash

Imai M amp Gentner D () A cross-linguistic study of early word meaning universalontology and linguistic influence Cognition () ndash

Johnson J S amp Newport E L () Critical period effects in second language learningthe influence of maturational state on the acquisition of English as a second languageCognitive Psychology () ndash

Jusczyk P W amp Aslin R N () Infantsrsquo detection of the sound patterns of words influent speech Infant Pathways to Language Methods Models and Research Directions() ndash

Keates J amp Graham S A () Category markers or attributes Why do labels guideinfantsrsquo inductive inferences Psychological Science () ndash

Klibanoff R S amp Waxman S R () Basic level object categories support the acquisitionof novel adjectives evidence from preschool-aged children Child Development ()ndash

Krehm M Onishi K H amp Vouloumanos A () I see your point infants under

months understand that pointing is communicative Journal of Cognition and Development() ndash

Krentz U C amp Corina D P () Preference for language in early infancy the humanlanguage bias is not speech specific Developmental Science () ndash

Kuhl P K Tsao F M amp Liu H M () Foreign-language experience in infancyeffects of short-term exposure and social interaction on phonetic learning Proceedings ofthe National Academy of Sciences of the United States of America () ndash

FERGUSON AND WAXMAN

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Landau B amp Shipley E () Labelling patterns and object naming DevelopmentalScience () ndash

Lewkowicz D J (a) Sensory dominance in infants I Six-month-old infantsrsquo response toauditory-visual compounds Developmental Psychology () ndash

Lewkowicz D J (b) Sensory dominance in infants II Ten-month-old infantsrsquo responseto auditory-visual compounds Developmental Psychology () ndash

Liszkowski U amp Carpenter M () Pointing out new news old news and absentreferents at months of age Developmental Science () Fndash

Lewkowicz D J amp Ghazanfar A A () The emergence of multisensory systemsthrough perceptual narrowing Trends in Cognitive Sciences () ndash

Lloyd-Fox S Szeacuteplaki-Koumlllőd B Yin J amp Csibra G () Are you talking to meNeural activations in -month-old infants in response to being addressed during naturalinteractions Cortex ndash

Lupyan G () The conceptual grouping effect categories matter (and named categoriesmatter more) Cognition () ndash

Lupyan G Rakison D H amp McClelland J L () Language is not just for talkingredundant labels facilitate learning of novel categories Psychological Science ()ndash

Mandler J M amp McDonough L () Concept formation in infancy CognitiveDevelopment () ndash

Marcus G F Fernandes K J amp Johnson S P () Infant rule learning facilitated byspeech Psychological Science () ndash

Marcus G F Fernandes K J amp Johnson S P () The role of association in earlyword-learning Frontiers in Psychology online lthttpdoiorgfpsyggt

Mareschal D amp Quinn P C () Categorization in infancy Trends in Cognitive Sciences() ndash

Marno H Davelaar E J amp Csibra G () Nonverbal communicative signals modulateattention to object properties Journal of Experimental Psychology Human Perception andPerformance () ndash

Marno H Davelaar E J amp Csibra G () An object memory bias induced bycommunicative reference Acta Psychologica (C) ndash

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May L amp Werker J F () Can a click be a word Infantsrsquo learning of non-native wordsInfancy () ndash

Mervis C B amp Rosch E () Categorization of natural objects Annual Review ofPsychology ndash

Mintz T H () Frequent frames as a cue for grammatical categories in child directedspeech Cognition () ndash

Murphy G L () Noun phrase interpretation and conceptual combination Journal ofMemory and Language () ndash

Murphy G L () The big book of concepts Cambridge MA MIT PressNamy L L amp Waxman S R () Naming and exclaiming infantsrsquo sensitivity to namingcontexts Journal of Cognition and Development () ndash

Namy L L amp Waxman S R () Symbols redefined In L L Namy (ed) Symbol useand symbolic representation ndash Malwah NJ Lawrence Erlbaum Associates

Palmer S B Fais L Golinkoff R M amp Werker J F () Perceptual narrowing oflinguistic sign occurs in the st year of life Child Development () ndash

Parise E amp Csibra G () Neural responses to multimodal ostensive signals in -month-old infants PLoS ONE ()

Pascalis O Loevenbruck H Quinn P C Kandel S Tanaka J W amp Lee K () Onthe links among face processing language processing and narrowing during developmentChild Development Perspectives () ndash

LINKING LANGUAGE AND CATEGORIZATION

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Peirce C S () Collected papers (eds) C Hartshorne amp P Weiss Cambridge MAHarvard University Press

Perszyk D Ferguson B amp Waxman S (in press) Maturation constrains the effect ofexperience in linking language and cognition evidence from healthy preterm infantsDevelopmental Science

Pinker S () The stuff of thought language as a window into human nature New YorkNY Viking Press

Pinker S amp Jackendoff R () The faculty of language Whatrsquos special about it Cognition() ndash

Plunkett K () Labels can override perceptual categories in early infancy Cognition() ndash

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Sloutsky V M amp Fisher A V () Linguistic labels Conceptual markers or objectfeatures Journal of Experimental Child Psychology () ndash

Sloutsky V M amp Robinson C W () The role of words and sounds in infantsrsquo visualprocessing from overshadowing to attentional tuning Cognitive Science () ndash

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Smith L B () Avoiding associations when itrsquos behaviorism you really hate InR M Golinkoff amp K Hirsh-Pasek (eds) Becoming a word learner a debate on lexicalacquisition ndash Oxford Oxford University Press

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FERGUSON AND WAXMAN

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Spelke E S amp Kestenbaum R () Les origines du concept drsquoobjet Psychologie Franccedilaise ndash

Syrett K Arunachalam S amp Waxman S R () Slowly but surely adverbs supportverb learning in -year-olds Language Learning and Development () ndash

Tincoff R amp Jusczyk P W () Some beginnings of word comprehension in -month-olds Psychological Science () ndash

Tincoff R amp Jusczyk P W () Six-month-olds comprehend words that refer to parts ofthe body Infancy () ndash

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Tomasello M amp Kruger A C () Joint attention on actions acquiring verbs in ostensiveand non-ostensive contexts Journal of Child Language () ndash

Valenza E Simion F amp Cassia V M () Face preference at birth Journal ofExperimental Psychology Human Perception and Performance () ndash

Vouloumanos A amp Waxman S R () Listen up Speech is for thinking during infancyTrends in Cognitive Sciences () ndash

Vouloumanos A Hauser M D Werker J F amp Martin A () The tuning of humanneonatesrsquo preference for speech Child Development () ndash

Vouloumanos A Martin A amp Onishi K H () Do -month-olds understand thatspeech can communicate Developmental Science () ndash

Vouloumanos A Onishi K H amp Pogue A () Twelve-month-old infants recognizethat speech can communicate unobservable intentions Proceedings of the NationalAcademy of Sciences of the United States of America () ndash

Vouloumanos A amp Werker J F () Tuned to the signal the privileged status of speechfor young infants Developmental Science () ndash

Vouloumanos A amp Werker J F () Listening to language at birth evidence for a biasfor speech in neonates Developmental Science () ndash

Vygotsky L S () Thought and language Cambridge MA MIT PressWaxman S R (a) Specifying the scope of -month-oldsrsquo expectations for novel wordsCognition () Bndash

Waxman S R (b) The dubbing ceremony revisited object naming and categorizationin infancy and early childhood In D L Medin amp S Atran (eds) Folkbiology ndashCambridge MA Bradford

Waxman S R () Early word learning and conceptual development everything had aname and each name gave birth to a new thought In U Goswami (ed) Blackwellhandbook of childhood cognitive development ndash Oxford Blackwell

Waxman S R amp Booth A () Seeing pink elephants fourteen-month-oldsrsquointerpretations of novel nouns and adjectives Infant Pathways to Language MethodsModels and Research Directions () ndash

Waxman S R amp Booth A () The origins and evolution of links between word learningand conceptual organization new evidence from -month-olds Developmental Science() ndash

Waxman S R amp Braun I () Consistent (but not variable) names as invitations to formobject categories new evidence from -month-old infants Cognition Bndash

Waxman S R amp Gelman S A () Early word-learning entails reference not merelyassociations Trends in Cognitive Sciences () ndash

Waxman S R amp Hall D G () The development of a linkage between count nouns andobject categories evidence from fifteen‐ to twenty‐one‐month‐old infants ChildDevelopment () ndash

Waxman S R amp Lidz J () Early word learning In D Kuhn amp R Siegler (eds)Handbook of Child Psychology th ed Vol ndash Hoboken NJ Wiley

Waxman S R Lidz J Braun I E amp Lavin T () Twenty-four-month-old infantsrsquointerpretations of novel verbs and nouns in dynamic scenes Infant Pathways toLanguage Methods Models and Research Directions () ndash

LINKING LANGUAGE AND CATEGORIZATION

terms of use available at httpwwwcambridgeorgcoreterms httpdxdoiorg101017S0305000916000568Downloaded from httpwwwcambridgeorgcore Northwestern University Libraries on 21 Nov 2016 at 195841 subject to the Cambridge Core

Waxman S R amp Markow D B () Words as invitations to form categories evidencefrom - to -month-old infants Infant Pathways to Language Methods Models andResearch Directions () ndash

Waxman S R amp Markow D B () Object properties and object kind twenty-one-month-old infantsrsquo extension of novel adjectives Child Development () ndash

Weisleder A amp Waxman S R () Whatrsquos in the input Frequent frames in child-directed speech offer distributional cues to grammatical categories in Spanish andEnglish Journal of Child Language () ndash

Werker J F amp Hensch T K () Critical periods in speech perception new directionsAnnual Review of Psychology () ndash

Werker J F amp Tees R () Cross-language speech perception evidence for perceptualreorganization during the first year of life Infant Behavior and Development () ndash

Winawer J Witthoft N Frank M C Wu L Wade A R amp Boroditsky L ()Russian blues reveal effects of language on color discrimination Proceedings of theNational Academy of Sciences of the United States of America () ndash

Woodward A L amp Hoyne K L () Infantsrsquo learning about words and sounds inrelation to objects Child Development () ndash

Wu R Gopnik A Richardson D C amp Kirkham N Z () Infants learn about objectsfrom statistics and people Developmental Psychology () ndash

Xu F () The role of language in acquiring object kind concepts in infancy Cognition

() ndashXu F Cote M amp Baker A () Labeling guides object individuation in -month-oldinfants Psychological Science () ndash

Yoon J M D Johnson M H amp Csibra G () Communication-induced memorybiases in preverbal infants Proceedings of the National Academy of Sciences of the UnitedStates of America () ndash

Yuan S amp Fisher C () lsquoReally He blicked the catrsquo Two-year-olds learn distributionalfacts about verbs in the absence of a referential context Psychological Science () ndash

Zosh J M and Feigenson L () Beyond lsquowhatrsquo and lsquohow manyrsquo capacity complexityand resolution of infantsrsquo object representations In L Santos amp B Hood (eds) The originsof object knowledge ndash Oxford Oxford University Press

FERGUSON AND WAXMAN

terms of use available at httpwwwcambridgeorgcoreterms httpdxdoiorg101017S0305000916000568Downloaded from httpwwwcambridgeorgcore Northwestern University Libraries on 21 Nov 2016 at 195841 subject to the Cambridge Core