Learning-disabled readers' working memory as a function of processing demands.

The purpose of this study was to investigate whether limitations in the enhancement of learning-disabled readers' working memory performance are attributable to process or storage functions. For Experiment 1, performance of reading-disabled, chronological age-matched, and reading level-matched children was compared on verbal and visual-spatial working memory measures under initial (no probes or cues), gain (cues that bring performance to an asymptotic level), and maintenance conditions (asymptotic conditions without cues). The results indicated that (a) learning-disabled readers' working memory performance was comparable on visual-spatial measures, but inferior to CA-matched children on verbal working memory measures; (b) learning-disabled readers' performance was superior to reading-matched counterparts across working memory conditions; and (c) performance differences remained between learning-disabled and CA-matched children or gain and maintenance conditions, even when initial and processing efficiency (probe) scores were partialed out in the analyses. Experiment 2 included the same conditions as Experiment 1, except that verbal short-term memory scores were also partialed out in the analysis. The results indicated that learning-disabled readers are inferior on both verbal and visual-spatial working memory measures when compared to CA-matched children on high demand conditions (maintenance). Two findings that emerged across experiments were (a) intercorrelations among diverse WM measures increased on demanding conditions and (b) verbal WM was not directly related to reading skill. In sum, the results support the notion that learning-disabled readers' poor working memory performance on demanding conditions reflect constraints in a central executive storage system.