Syntactic categories in the speech of young children.

This article demonstrates that very young children have knowledge of a range of syntactic categories. Speech samples from six children aged 2 years to 2 years, 5 months, with Mean Lengths of Utterance (MLUs) ranging from 2.93 to 4.14, were examined for evidence of six syntactic categories: Determiner, Adjective, Noun, Noun Phrase, Preposition, and Prepositional Phrase. Performance was evaluated by the conformance of the children's speech to criteria developed for each category. Known syntactic diagnostics served as models for the criteria developed; the criteria exploited distributional regularities. All children showed evidence of all categories, except for the lowest MLU child, whose performance was borderline on Adjectives and Prepositional Phrases. The results suggest that children are sensitive very early in life to abstract, formal properties of the speech they hear and must be credited with syntactic knowledge at an earlier point than heretofore generally thought. The results argue against various semantic hypotheses about the origin of syntactic knowledge. Finally, the methods and results may be applicable to future investigations of why children's early utterances are short, of the nature of children's semantic categories, and of the nature of the deviance in the speech of language-deviant children and adults. The grammars of mature speakers consist of rules and principles that capture generalizations about the language. Languages have (minimally) semantic, syntactic, and phonological regularities, and mature grammars represent all three levels of regularities. Three enduring questions of language acquisition are to what extent a child's grammar resembles a mature grammar, how a child's grammar develops over time, and how the components of the child's grammar are interrelated. Since syntactic regularities are stated in terms of syntactic categories like Adjective, Noun, and Noun Phrase, categories are particularly important entities. If the child's grammar lacks syntactic categories, it also lacks a level of syntactic description, and thus differs from a mature grammar in a crucial way. By what point in development has the child acquired the basics of formal grammatical categories like Adjective and Noun? The present study addresses a special case of this question by examining corpora of 2-year-olds for evidence of formal regularities characterizing six categories. The results bear on several theoretical concerns about acquisition. First, from a semantic viewpoint, treatments of semantic roles presuppose a phrasal segmentation of the sentence, with the senses of Noun Phrases identifying roles like agent of the action or recipient of the action (e.g., Hardy