Phonological Processing Deficits as the Basis of a Reading Disability

Abstract

Stanovich (1988a, 1988b) has proposed that deficits in phonological processing are at the basis of reading problems. According to his theoretical approach, phonological processing constitutes a modular function that operates automatically and is independent of general cognitive ability. If this is the case, then phonological processing skills should be relatively independent of performance on IQ tests. The purpose of this study was to examine the evidence for the independence of phonological skills and general cognitive processes. To examine this hypothesis, regression analyses were conducted to examine the relative contribution of IQ and phonological processing skills to word recognition and reading comprehension. The correlations between IQ test scores and phonological processing skills were also examined. A sample of 1493 children, including both reading disabled and normally achieving children, was administered a variety of phonological processing, word recognition, spelling, and reading comprehension measures. The phonological processing measures included pseudoword reading and spelling, recognizing the visual form of a pseudoword, and a phonological–lexical task that involved deciding whether a pseudoword could be pronounced like an English word. It was predicted that phonological skills should be the most significant correlate of reading performance and that IQ scores should contribute relatively little independent variance. In addition, it was predicted that the correlations of phonological processing and reading skills would be significantly higher than the correlations of IQ scores with reading skills. The results indicated that pseudoword reading skill was the most significant correlate of word recognition and reading comprehension scores and that IQ contributed little independent variance. Correlations among reading and phonological abilities were significantly higher than IQ with either of these abilities. Phonological processing deficits appear to be the fundamental problem of reading disabled individuals and there is evidence that phonological processing is a modular function that is relatively independent of general cognitive ability.