Subject Case in Children With SLI and Unaffected Controls: Evidence for the Agr/Tns Omission Model

Abstract

We present new evidence for the view that specific language impairment (SLI) involves a syntactic feature deficit within a nondeviant grammar. The data involve morphological case and its interaction with verbal inflection. Children with SLI (like younger unaffected children) produce certain pronoun forms in contexts that do not exist in adult language, for example, Him run, which we take as important evidence about their grammars. Both unaffected children and those with SLI show a distributional asymmetry in their production of non-nominative versus nominative pronouns as subjects: Nominatives appear abundantly with both uninflected and agreeing verbs, whereas non-nominatives almost never appear with agreeing verbs. This contingency is predicted on the: view that children are conforming to Universal Grammar, extrapolating beyond their input data. The findings are explained by a model in which the syntactic features Agreement and Tense are optionally omitted from the clause structure.