Past-tense morphology and phonological deficits in children with dyslexia and children with language impairment

The authors investigated past-tense morphology problems in children with dyslexia compared to those classically observed in children with oral language impairment (LI). Children were tested on a past-tense elicitation task involving regulars (look-looked), irregulars (take-took), and nonwords (murn-murned). Phonological skills were also assessed, using tests of nonsense word reading and phoneme elision. Analyses focused on whether children with dyslexia and LI showed overlapping patterns of morphological and phonological difficulties compared to controls with typical reading and language levels. Both the groups with LI and dyslexia had difficulty generating past tenses overall, although the deficit was less pronounced in dyslexia. Both groups also showed similar problems with phonological processing. The results have important implications for the theory that both language and reading problems involve oral language processing deficits. Specifically, our data support the theory that the phonological deficits observed in both dyslexia and LI are related to deficits in morphological processing. However, some important differences between dyslexia and LI are also discussed.