The roles of verbal short-term memory and working memory in the acquisition of grammar by children with Williams syndrome

The roles of verbal short-term and working memory were examined in a sample of children with Williams syndrome (mean chronological age 10 years, 2 months) and a sample of grammar-matched children who are developing normally. Forward digit span, nonword repetition, and backward span were all found to be correlated with receptive grammatical ability in the sample of children with Williams syndrome, but not in the sample of children who are developing normally. The relation between working memory, as measured by backward digit span, and grammatical ability was found to be significantly stronger in children with Williams syndrome than in the control group. This finding highlights the possibility that children with Williams syndrome may rely on their working memory to a greater extent than children who are developing normally to learn grammar. Hierarchical regression analyses indicated receptive vocabulary may mediate the relations among forward digit span, backward digit span, and grammatical ability for the children with Williams syndrome. Phonological short-term memory, however, contributed independently to grammatical ability even after receptive vocabulary was taken into account.