Dissociable components of shortterm memory and their relation to long-term learning

ABSTRACT—Verbal working memory consists of separable capacities for the retention of phonological and semantic information. Within the phonological domain, there are independent capacities for retaining input-phonological codes and output-phonological codes. The input-phono-logical capacity does not appear to be critical for language comprehension but is involved in verbatim repetition and long-term learning of new words. The semantic capacity is critical for both comprehension and production and for the learning of new semantic information. Different neural structures appear to underlie these capacities, with a left-parietal region involved in input-phonological retention and a left-frontal region involved in semantic retention. KEYWORDS—short-termmemory; sentence comprehension; language production; verbal learning; neuropsychology Most cognitive psychologists take for granted the notion that language comprehension draws on working memory (the system that stores information temporarily and allocates attention to the processing of this information). Traditionally, memory span (or the number of words that can be recalled in order) has been used as a measure of the storage-capacity component of working memory, often referred to as short-term memory (STM) capacity. Neurally intact individuals have a span of about five words. Thus, one might expect that a brain-damaged patient or a child with a developmental disorder who had a memory span of only one to two words would, as a result, have problems with under-standing language. Many studies from our lab have shown, however, that whether or not there is a connection between re-duced span and difficulties with language processing depends on the specific source of the STM deficit and the specific type o