According to the theory of 'Preferred Argument Structure' (PAS), the realisation and distribution of core arguments including the subject of a transitive verb (A), the direct object of a transitive verb (O) or the subject of an intransitive verb (S) in spoken discourse are subject to both grammatical and pragmatic constraints. However, previous studies on the formulation of argument structure have largely focused on the syntactic difficulties of children with SLI. In addition, little is known about the developmental outcomes in argument structure for adolescents with SLI. In this study, we compared PAS in the narratives of 19 adolescents with SLI (Mean age = 14.3; SD = 0.64) and 19 adolescents with typical language development (TLD; Mean age = 14.5; SD = 0.84). The core arguments of the predicate in each narrative based on the wordless picture storybook 'Frog, where are you?' were coded for grammatical roles (A, O and S), referential forms (lexical forms and non-lexical form including null and pronominal forms) and information status (given, accessible and new information). The data were then analysed for conformity to the grammatical and pragmatic constraints of the PAS theory. The two groups were found to be similar in their conformity to the pragmatic constraints but differed in how they conform to the syntactic constraints. In particular, the adolescents with SLI were more likely to produce clauses with two lexical arguments, and the lexical arguments occurred significantly more frequently at the subject role of a transitive verb than the TLD groups. Our results provide further evidence that it is a persistent grammatical deficit, rather than a pragmatic deficit, which poses a special challenge for adolescents with SLI in their formulation of argument structure in narratives.
Keywords: DLD; SLI; adolescents; oral narratives; pragmatic constraints; preferred argument structure; syntactic constraints.