Abstract
The present paper investigates the verbal and non-verbal abilities of a group of ten individuals with Williams syndrome (WS) in order to explore the debates surrounding the language functioning of this population and the controversial claims that the WS profile supports the dissociation between language and cognition as well as possible dissociations within the language module. A range of standardized and non-standardized measures was employed to assess WS individuals' language abilities with particular focus on two morphosyntactic phenomena, past tense and plural inflection. These morphosyntactic features were investigated through three assessment types: elicitation, comprehension and repetition. Performance was compared with chronological and cognitive age-matched Down's syndrome (DS) controls as well as with a younger cognitively age-matched typically developing (TD) cohort. Overall results for the WS group reveal significant linguistic impairments across most of the language measures with little evidence of the reported spared linguistic abilities in the WS population. Better performance was evident on standardized lexical versus grammatical tasks. A regularity advantage in the WS group with both past tense and plural elicitation was replicated in the TD group, and in the DS cohort with plurals. The relatively poor performance of the WS group on both past tense elicitation and comprehension, and the better performance on plurals reflect difficulties with the concept and understanding of past tense in the context of a better understanding of number.
Notes
1 Mental ages were derived from performance IQ from the WISC III or WPSSI-R.