Are dyslexics different? II. Individual differences among dyslexics, reading age controls, poor readers and precocious readers

Cognitive neuropsychological analyses of developmental dyslexia have suggested that different forms of dyslexia exist, and that these forms resemble some of the varieties of acquired dyslexia which can be observed in previously literate people following brain injury. Thus, developmental ‘phonological’ dyslexics are meant to have a relatively intact ability to recognize words as whole visual units but to be especially poor at phonic letter‐sound conversion. Developmental ‘surface’ dyslexics show the opposite pattern, with relatively intact phonic skills but poor whole word recognition. Bryant and Impey argued that such individual differences were not unique to dyslexics but could be observed in younger normal children of the same reading age. In the present study we investigate individual differences among four groups of readers matched on reading age—dyslexics, younger reading age controls, ordinary poor readers and very young precocious readers. Whole word recognition was assessed through the accuracy of reading aloud words with exceptional spellings, while letter‐sound conversion was assessed through the reading of non‐words. Substantial individual differences were observed within the dyslexic group, with both phonological and surface patterns being apparent, but equally substantial individual differences were present in the other three groups. There was no evidence that children in any of the groups clustered into distinct subtypes. Across the four groups non‐word reading accuracy correlated significantly with other tests of phonological processing ability, but we were unable to identify any cognitive factor which correlates significantly with the accuracy of reading exception words.