A longitudinal perspective on the study of specific language impairment: the long term follow-up of an Italian child

Most of the literature on children with specific language impairment (SLI) is centred on the study of cross-sectional samples and little is known on h ow language develops in these children - that is, whether it occurs along s teps and modes analogous to those observed in normal acquisition, the only difference being significant slowness, or following rather idiosyncratic co urses leading to atypical results. This paper presents findings from a long itudinal study of the acquisition of formal aspects of Italian grammar in a child with severe SLI of the so-called phonologic-syntactic subtype or gra mmatical SLI. The analysis concerns a set of morphosyntactic phenomena suff iciently differentiated in terms of both grammatical properties and modes o f acquisition in normal development, so as to offer a panorama that approxi mates to what can be thought of as an overall morphosyntactic competence: ( 1) free morphology (prepositions, clitics and articles); (2) bound morpholo gy (verb inflection); (3) WH movement (questions and relative clauses) and (4) the evolution of complex sentences. These phenomena will be dealt with in four independent studies. This paper argues that each domain or even eac h sub-domain presents its own set of properties, some of which are common t o other domains but some of which are not. The results reveal the existence of important dissociations among the various domains and even within speci fic sub-domains. These dissociations may be ascribed to deficits affecting specific properties of functors or constructions. The picture that emerges is one in which the deficit involves, rather than morphology in the strict sense of a bare set of paradigmatic forms, some properties or components of syntax which are involved in the use, not only of certain morphemes, but o f certain extended syntactic constructions as well. This result will be che cked against the most widely held current theoretical approaches to SLI.