Language and Speech A. Christophe, S. Millotte, S. Bernal, J. Lidz 61Bootstrapping Lexical and Syntactic AcquisitionAnne Christophe1,2, Séverine Millotte1,3, Savita Bernal1, Jeffrey Lidz41 Laboratoire de Sciences Cognitives et Psycholinguistique, EHESS /CNRS/ DEC-ENS, Paris 2 Maternité Port-Royal, AP-HP, Faculté de Médecine Paris Descartes3 Laboratoire de Psycholinguistique Expérimentale, Genève4 Cognitive Neuroscience of Language Laboratory, Department of Linguistics, University of Maryland, U.S.A. 1IntroductionInfants acquiring language have to learn about the lexicon, the phonology, and the syntax of their native language. For each of these domains, being able to rely on knowledge from the other domains would simplify the learner’s task. For instance, since syntactic structure spells out the relationships between words in a sentence, it Language and SpeechAbstractThis paper focuses on how phrasal prosody and function words may interact during early language acquisition. Experimental results show that infants have access to intermediate prosodic phrases (phonological phrases) during the first year of life, and use these to constrain lexical segmentation. These same intermediate prosodic phrases are used by adults to constrain on-line syntactic analysis. In addition, by two years of age infants can exploit func-tion words to infer the syntactic category of unknown content words (nouns vs. verbs) and guess their plausible meaning (object vs. action). We speculate on how infants may build a partial syntactic structure by relying on both phonological phrase boundaries and function words, and present adult results that test the plausibility of this hypothesis. These results are tied together within a model of the architecture of the first stages of language processing, and their acquisition. Key wordsfunction wordslanguage acquisitionphrasal prosody Acknowledgments: The work presented in this paper was supported by a grant from the French ministry of Research to the first author (ACI n° JC6059), by two grants from the Direction Générale de l’Armement to the second author (PhD and post doctoral fellowships), by a PhD grant from the French Ministry of Research to the third author, by a CNRS Poste Rouge to the fourth author (in 2004), by a grant from the National Institute of Health (R03-DC006829) by a grant from the Agence Nationale de la Recherche (“Acquisition précoce du lexique et de la syntaxe,” n° ANR-05-BLAN-0065- 01) and by the European Commission FP6 Neurocom project. Address for correspondence. Anne Christophe, LSCP, ENS, 29, rue d’Ulm, 75005 Paris, FRANCE; phone: (33) 01 44 32 26 18; fax: (33) 01 44 32 26 30; e-mail: < [email protected] >. LANGUAGE AND SPEECH, 2008, 51 (1&2), 61–75 Language and Speech ‘Language and Speech’ is © Kingston Press Ltd. 1958 – 2008Language and Speech 62 Bootstrapping language acquisitionmakes sense to assume that infants need to have access to words and their meanings in order to learn about syntax. Conversely, learning about the meaning of words would be greatly facilitated if infants had access to some aspects of syntactic structure (Gillette, Gleitman, Gleitman, & Lederer, 1999; Gleitman, 1990). These potential circularities can partially be solved if infants can learn some aspects of the structure of their language through a surface analysis of the speech input they are exposed to. Morgan and Demuth (1996) introduce the term phonological bootstrapping to express the idea that a purely phonological analysis of speech may give infants some information about the structure of their language.In this paper, we focus on the very beginning of language acquisition, and consider processes that may happen during the first two years of life. More specifi-cally, we discuss how infants may start building a lexicon, and how they may start acquiring rudiments of syntax, that is, building the skeleton of a syntactic tree. In particular, we examine the role of two sources of information to which very young infants may plausibly have access: phrasal prosody and function words. The model in Figure 1 summarizes our hypotheses about the architecture of the speech processing system and its acquisition.Figure 1A model of speech processing and early language acquisitionOne central feature of this processing model is the existence of a prelexical phonological representation containing information both on the phonetic content of the utterance and on its prosodic structure (see Figure 1). This prelexical representation Pre-lexical phonologicalrepresentation with prosodic structureSyntactic representation(partial in infants)Speech signal[&N+VNDnL]PP [+UT¡P+0H#ÖUV]PPLexicon(content words)[the xxx]NP [is xxx]VPTim e (s)0.71.2-0.3 0940.33 490Function words"the little boy is running fast"prosodicboundaries areused in syntacticrepresentationFunction word -strippingPhonetic and prosodicanalysisFrequentsyllables atprosodicedgesLexical access andvarious word-segmentation strategies(e.g. known words,phonotactics, etc)Function wordsfill in syntacticrepresentationContent wordsfill in syntacticrepresentationLanguage and Speech A. Christophe, S. Millotte, S. Bernal, J. Lidz 63is computed from the speech signal and used for lexical access. Thus, one prediction of the model is that lexical access occurs within the domain of units defined by phrasal prosody, such as phonological phrases: The first section of this paper reviews experimental data showing that both infants and adults rely on phonological phrase boundaries to constrain on-line lexical access. Phrasal prosody, the rhythm and melody of speech, has long been known to be processed very early on by infants (see e.g., Mehler, Jusczyk, Lambertz, Halsted, Bertoncini, & Amiel-Tison, 1988), and has often been assumed to provide them with information about some aspects of their mother tongue (see e.g., Christophe, Nespor, Guasti, & van Ooyen, 2003; Gleitman & Wanner, 1982; Morgan, 1986).A second crucial aspect of the model is the special role played by function words (e.g., determiners, auxiliaries, prepositions, etc.). They are represented within a special lexicon, that is built and accessed from the prelexical representation (paying special attention to prosodic edges) and that directly informs syntactic processing. Infants may be able to discover function words quite early in their acquisition of language because they are extremely frequent syllables that typically