Verbal short-term memory deficits in Down syndrome: A consequence of problems in rehearsal?

Individuals with Down syndrome suffer from relatively poor verbal short-ter m memory. Previous explanations of this deficit have been framed in terms o f inefficient or absent rehearsal of verbal material in Down syndrome withi n the phonological loop component of Baddeley and Hitch's (1974) working me mory model. Two experiments are presented which test this explanation by lo oking for the markers of rehearsal in children with Down syndrome and verba l mental age matched controls. Both experiments confirm that individuals wi th Down syndrome show poorer verbal short-term memory performance than cont rols. However, they rule out rehearsal as an explanation of these deficits because the evidence suggests that neither individuals with Down syndrome n or matched controls are engaging in spontaneous subvocal rehearsal. Other e xplanations of poor verbal short-term memory performance in Down syndrome, in terms of impairments both within and outside of the phonological loop sy stem, are discussed. Practical implications for intervention strategies aim ed at improving verbal short-term memory skills in Down syndrome are also o utlined.