Semantic and phonological loop effects on verbal working memory in middle-age adults with mental retardation.

Semantic and phonological loop effects on verbal working memory were examined among middle-age adults with Down syndrome and those with unspecified mental retardation in the context of Baddeley's working memory model. Recall was poorer for phonologically similar, semantically similar, and long words compared to recall of dissimilar short words. Compared to their peers, participants with Down syndrome had poorer recall in all categories except phonologically similar words. Most interestingly, semantic similarity lowered recall scores only in participants with Down syndrome. This selective effect of semantics reflects an influence of long-term memory on working memory and points to the need for additional explanations outside phonological loop processes to completely account for the relative impairment of verbal working memory among individuals with Down syndrome.