Formal features in impaired grammars: A comparison of English and German SLI children

One important problem in the recent theoretical debate on Specific Language Impairment (SLI) is that most of the SLI accounts have not yet been rested crosslinguistically. As a step towards a crosslinguistic characterization of SLI, we directly compare data from nine English and six German SLI subjects in this paper. We found that subject-verb agreement is more impaired than tense marking, and that all SLI subjects achieve low scores for subject-verb agreement. Moreover, we found that SLI children produce structures which have been reported to be absent from the speech of unimpaired children, e.g. root infinitives with fully specified subjects and verb-second patterns with non-finite verbs. The results will be explained in terms of the agreement-deficit hypothesis: formal features which do not have a semantic interpretation, specifically phi-features of verbs, cause acquisition problems for SLI children.