Phonological Short-term Memory and its Relationship to Language in Williams Syndrome

Williams syndrome (WS), a rare neurodevelopmental disorder of genetic origin, is characterised by a relative advantage of language over more serious deficits in other cognitive domains. In this study the relationship of phonological short-term memory to WS language, in particular vocabulary, was explored. Using Gathercole and Baddeley's Children's Test of Nonword Repetition (CNRep) (Gathercole & Baddeley, 1996), we examined the pattern of performance by WS participants on that task and compared it to performance on measures of receptive language, visuospatial ability, and digit span. In addition, a comparison was made of WS nonword repetition score with those of two groups of individually matched normally developing 5-year-olds, one on the basis of nonverbal test age and the other on the basis of verbal test age. As expected WS repetition scores showed an effect of nonword length but not of phonological complexity. Nonwords that were relatively wordlike were better repeated than nonwords that were less wordlike. CNRep scores were correlated with test ages on TROG, Ravens, and digit span but not with chronological age. Test age on the CNRep was at a similar level to that on TROG, Ravens, and digit span but significantly lower than on BPVS. The results lend support to the view that phonology in WS is a relative strength. In contrast, despite relatively good productive and receptive vocabulary, certain aspects of the processes of word learning in WS do not seem to develop beyond that of normal 4year-olds. The good vocabulary scores of older children and adults with WS may be simply due to their relatively good phonological short-term memory.