Specific language impairment: a deficit in grammar or processing?

Specific Language Impairment (SLI) is observed in children who fail to acquire age-appropriate language skills but otherwise appear to be developing normally. There are two main hypotheses about the nature of these impairments. One assumes that they reflect impairments in the child's innate knowledge of grammar. The other is that they derive from information-processing deficits that interfere with several aspects of language learning. There is considerable evidence that SLI is associated with impaired speech processing; however, the link between this deficit and the kinds of grammatical impairments observed in these children has been unclear. We suggest that the link is provided by phonology, a speech-based code that plays important roles in learning linguistic generalizations and in working memory.