Four-Word Combinations Stored Word Sequences in Language Learning: The Effect of Familiarity on Children's Repetition of

ABSTRACT— Recent accounts of the development of gram-marproposethatchildren rememberutterances theyhearand draw generalizations over these stored exemplars.Thisstudytestedthese accounts’assumptionthatchildrenstore utterances as wholes by testing memory for familiarsequencesofwords.Usinganewlyavailable,densecorpusof child-directed speech, we identiﬁed frequently occur-ring chunks in the input (e.g., sit in your chair ) andmatched them to infrequent sequences (e.g., sit in yourtruck). We tested young children’s ability to produce thesesequences in a sentence-repetition test. Three-year-olds(n 5 21) and 2-year-olds (n 5 17) were signiﬁcantly morelikelytorepeatfrequentsequencescorrectlythantorepeatinfrequent sequences correctly. Moreover, the 3-year-oldswere signiﬁcantly faster to repeat the ﬁrst three words ofan item if they formed part of a chunk (e.g., they werequicker to say sit in your when the following word waschair than when it was truck). Wediscuss the implicationsof these results for theories of language development andprocessing.Perhaps the most remarkable thing about language is its com-positional nature—thefactthat alimited number of sounds canbearrangedinunfamiliarcombinationstoproducenovelmean-ings.Soimpressiveissuchproductivegrammarthatresearchershave often argued it would be impossible to learn—it mustsomehowbeinnate.However,anumberofrecentaccountsproposethat children acquire the grammar of their native language (orlanguages) simply by observing patterns and generalizations inthe input. One such view that has been gaining in popularity isthe constructivist, or usage-based, account (e.g., Goldberg,2006; Tomasello, 2003). Accordingtothisaccount,childrenbeginwitharestrictedsetof utterances taken directly from experience and acquired viathe domain-general skills of imitation and intention reading.Childrenthenadvancetoproductivesyntaxbygeneralizingoverthese utterances. This account relies on certain controversialassumptions. The most fundamental is that children are able tostore whole sequences of words taken directly from the input.Although naturalistic observation supports this assumption(e.g., Clark, 1970; Lieven, Behrens, Speares, & Tomasello,2003; Peters, 1983), no experimental work has tested it. Thestudy reported in this article tested experimentally whetherchildren store and reuse sequences of multiple words.One reason one might expect children to store more than in-dividual words in memory is that they do not hear demarcatedwords in the input; words and phrases run into one another andmust be detected in the speech stream. Recently, it has beenargued that children could segment speech by observing howregularly sounds co-occur in the language. Sounds that occurtogether frequently can be taken to be words or components ofwords. Conversely, word boundaries can be posited at pointswhere low-frequency transitions between sounds are observed(Saffran,Aslin,N Thiessen& Saffran,2003). Achild performing segmentation in this fashion is likely to arriveat an inventory of segments containing not just conventionalwords, but also a number of multiword sequences.Figure1illustratesthisargumentbyshowingthefrequencyofunits of between one and ﬁve words observed in a 1.7-million-wordcorpusofonemother’sspeechtoherchild(seetheMethodsection for details). The ﬁgure plots frequency against rank on