The effects of orthography, phonology, semantics, and working memory on the reading comprehension of children with and without reading dyslexia.

In this study, we examined to what extent orthographic skills, phonological processing, oral vocabulary, and word memory accounted for variance in reading comprehension among upper-elementary school children with and without dyslexia. The tasks came from the Tests of Dyslexia (TOD). Data from 753 participants (typically developing n = 575; children with dyslexia n = 143) ages 8 to 11 were analyzed with t-tests and multiple regression models. Performance of typically developing children was significantly higher than children with dyslexia on all tasks (p < .001). Typically developing children exhibited age-related improvements, though this association was absent in children with dyslexia. Among typically developing children, orthographic mapping, phonological awareness, oral vocabulary, and working memory scores uniquely explained reading comprehension. Among children with dyslexia, only orthographic mapping and oral vocabulary scores uniquely predicted reading comprehension. Our findings highlight the strong effects of orthographic mapping on reading comprehension observed across both groups. Limitations and educational implications are discussed.