Genetically dissociated components of working memory: evidence from Down'sand Williams syndrome

Wang and Bellugi [J clin exp Neuropsychol 1994;16:317-22] have suggested th at Down's and Williams syndrome might be associated with specific and contr asting working memory deficits; with impaired verbal short-term memory in D own's syndrome, and a visuo-spatial short-term memory deficit in Williams s yndrome. In two studies we examine whether these apparent deficits might si mply be a consequence of the general pattern of learning difficulties assoc iated with these disorders. Experiment 1 compared verbal and visuo-spatial short-term memory abilities in these groups, using analysis of covariance t o control for mental age differences. In Experiment 2 individuals with Will iams syndrome were matched to control groups for non-verbal mental age, and the short-term memory abilities of these matched groups were compared. The results of both experiments are broadly consistent with those reported by Wang and Bellugi, and support the view that working memory can be dissociat ed into Separate subsystems. (C) 1999 Elsevier Science Ltd. All rights rese rved.