Words and Rules in Children with Williams Syndrome

2 1. Introduction Williams syndrome [WS] is a genetic disorder associated with learning difficulties, with an incidence of 1 in 25,000 (Greenberg, 1990). It is caused by a microdeletion on the long arm of chromosome 7 at 7q11.23, which affects one allele of the elastin gene and other contiguous genes (Ewart et al. Frangiskakis et al., 1996). Within cognitive skills, there is a spatial disorder, for example in drawing and relative strength in language. The development of language is also uneven but there is dispute about the actual performance on language tasks and the best theoretical interpretation of this performance. In two previous studies investigating morpho-syntactic skills in subjects with WS, Clahsen and Almazan (1998, 2001) found that the subjects with WS do not show any syntactic impairment, and that they perform excellently on regular past tense and regular plural inflection. On the other hand, their scores on irregular past tense and irregular plural forms were found to be lower than those of unimpaired mental age controls, and the subjects with WS were seen to use regular rules of inflection excessively, even in circumstances in which unimpaired children (and adults) would not use them. Another finding from these studies was that the grammatical profile of WS does not extend to children with Specific Language Impairment (SLI). A comparison of the results from the WS subjects to those of SLI studies using the same experimental tasks revealed differences, with the SLI children showing weaknesses on syntactic tasks and regular inflection paired with relatively well-preserved lexical skills. proposed an account of the unusual pattern of morpho-syntactic skills in WS, in terms of a modular view of the language faculty in which the knowledge of language is assumed to consist of two separate components, a lexicon of stored entries and a computational system of combinatorial operations to form larger linguistic expressions (e.g. Chomsky 1995, Pinker 1999). They argued that these two core modules of language are dissociated in WS such that the computational (rule-based) system for language is selectively spared, while lexical representations and/or their access procedures are impaired. They also argued that this pattern of skill dissociation does not hold for SLI. The present study provides new evidence from three sources for a modular account of the linguistic skills of subjects with WS. Results will be presented on the use of comparative adjectives, receptive and productive vocabularies and reading skills in WS. …