Auditory comprehension in children with specific language impairment: The role of verbal working memory

This study investigates the auditory comprehension of complex language and the comprehension of short stories by children diagnosed with specific language impairment (SLI). Specifically, it addresses the role of verbal working memory in story comprehension. A major question in the study concerns the relative importance of two components of verbal working memory: phonological working memory and capacity of verbal memory. Previous research has investigated these aspects of verbal working memory and children's comprehension of complex sentences; the present study extends this research to include the comprehension of connected discourse. Current views on verbal working memory place different emphases on the functions of phonological working memory and capacity of verbal working memory. In Baddeley's (1986, 1992) model phonological memory is paramount, and regulated by a central executive component, which has a limited capacity. Just and Carpenter (1992) propose a functional working memory model; they place the emphasis for complex language processing solely on the capacity of the central executive component, which is responsible for activation of phonological, morphological, and syntactic representations. Fifty three children between the ages of 6 and 12 participated in this study (33 children with SLI and 20 controls). The children completed a battery of experimental and standardized tests. Phonological working memory was assessed through the Nonsense Word Repetition Task (NWRT), and verbal working memory capacity through the Competing Language Processing Task (CLTP). As hypothesized, children with SLI showed decreased capacity compared with typical language developing controls, and showed different patterns of association between the capacity measure and short story comprehension. A major finding of the study was that for children with SLI, but not for typically developing children, there was a direct correlation between capacity measures and comprehension measures. Moreover, phonological memory scores predicted comprehension for only the youngest children in either group. The results of the present study suggest that the difficulties children with SLI have in comprehending connected discourse are attributable to capacity limitations and can be explained by Just and Carpenter's (1992) functional working memory model.