On the basis of Baddeley's working memory model (1986), we examined working memory functioning in children with learning disorders with and without specific language impairment (SLI). We pursued the question whether children with learning disorders exhibit similar working memory deficits as children with additional SLI.
In separate analyses, we compared the following groups of children: (1) 30 children with dyslexia (DYS) and 16 children with DYS receiving special language education and (2) 19 children with combined disorder of scholastic skills (CDSS) and 18 children with CDSS receiving special language education. A control group of 30 typically developing children was included in each comparison. All of the children receiving special language education met criteria for SLI. To assess the 3 subcomponents of working memory (phonological loop, visual–spatial sketchpad, central executive), the children worked individually on an extensive test battery.
We found deficits in the phonological loop and central executive functioning for children with dyslexia (and CDSS) as well as for children with additional SLI. Deficits in phonological functioning were broader and more profound for children with SLI. Deficits in visual–spatial sketchpad could only be found for children with CDSS without SLI.
Children with isolated learning disorder and children with additional SLI demonstrate similarities and differences in working memory functioning. These findings support our hypothesis that underlying working memory deficits for the different disorders partly overlap but also are distinct and partly distinguish between certain disorders.