Three accounts of the grammatical morpheme difficulties of English-speaking children with specific language impairment.

Several hypotheses have been offered to explain the grammatical morpheme difficulties observed in the speech of children with specific language impairment. Three of the accounts that could be evaluated in English were the focus of this study: the extended optional infinitive account, the implicit rule deficit account, and the surface account. Preschoolers with specific language impairment, a group of age controls, and a group of younger children matched for mean length of utterance were evaluated in their use of several theory-relevant grammatical morphemes. The findings revealed advantages for both the surface and extended optional infinitive hypotheses. In contrast, a test of the predictions based on the implicit rule deficit account suggested that the children studied here were not experiencing a deficit of this type.