Down syndrome and the phonological loop: the evidence for, and importance of, a specific verbal short-term memory deficit.

Individuals with Down syndrome are thought to perform poorly on tests of verbal short-term memory, such as measures of word span or digit span. This review critically examines the evidence for a specific deficit in verbal short-term memory in Down syndrome, and outlines a range of possible explanations for such a deficit. The potential implications of a verbal short-term memory impairment for broader aspects of development are outlined, in particular with respect to vocabulary development. Possible intervention strategies, which might improve verbal short-term memory performance in Down syndrome are also considered. However, we argue that further research is needed to fully clarify the nature of a verbal short-term memory deficit in Down syndrome, before the merits of these various intervention approaches can be properly evaluated.