Short-term and working memory in children with specific language impairment
Investigations of the cognitive processes underlying Specific Language Impairment (SLI) have implicated deficits in the storage and processing of phonological or verbal information. This thesis reports five studies that investigated the role of short-term and working memory in children with SLI. Study 1 demonstrated SLI deficits on measures of verbal working memory, and short-term memory for verbal but not visuospatial information. Study 2 provided evidence that children with SLI perform at age-level on visuospatial working memory measures. Study 3 demonstrated slower processing in the SLI group across domains, as well as verbal storage decrements, with the greatest deficits found for tasks tapping both of these. Study 4 found SLI deficits on measures of nonword repetition in common use, with greater impairments on the task that relied to a lesser extent on short-term memory. Study 5 established more accurate recall for multisyllabic nonwords than matched single syllable lists for all groups, although the SLI group showed different patterns of phoneme retention. It is suggested that the combination of deficits in generalized processing speed and verbal storage in SLI may be expected to have a drastic and detrimental impact on learning, and provides an account of the disorder that could encompass the range of impairments observed in SLI. The findings also suggest that factors additional to short-term memory contribute to poor nonword repetition in SLI.