Syntactic development in high-functioning individuals with Down Sydrome

This project investigates complex syntax in individuals with Down Syndrome. Subjects are intitally selected on the basis of parental/caretaker report of the subject's ability to read. Both comprehension and production are studied. Our results indicate that about a third the 25 subjects who have taken part have an ability to comprehend and produce complex sentence structures well beyond the three year old age equivalent level often reported in the literature. For example, some of our subjects understand the difference between 'John is eager to kiss' (John kisses someone) and 'John is easy to kiss' (John is kissed by someone). This contrast is not generally mastered by typically developing children until around eight years of age. In production, we have evidence of use of a variety of complex (embedded) sentence types, including adverbial and relative clauses and complements to verbs. The chronological age range of our subjects is 8-33 years. Our higher-performing subjects are in the older part of this range, and we hope in future research to contrinue tracking the younger subjects, to study the time course of grammatical development in persons with Down Syndrome.