The Validity of Perceptual Deficit Explanations of Reading Disability: A Reply to Fletcher and Satz

In the preceding paper Fletcher and Satz present a number of counter arguments against my contention that reading disability is not caused by perceptual deficiency in the sense in which this term is traditionally employed (Vellutino, in press). These authors question the position I have taken on both methodological and theoretical grounds and critique in some detail the procedures and conclusions drawn from certain studies conducted in our laboratory (Vellutino, Smith, Steger, & Kaman 1975, Vellutino, Steger, & Kandel 1972) and elsewhere (Ailington, Gormley, & Truex 1976). They also express doubt that dysfunction in verbal mediation is a viable interpretation of the reader group differences observed in these studies. In an apparent reference to my suggestion that reading disorder may be associated with deficiencies in verbal skills, the authors contend that unitary deficit explanations cannot adequately account for the multitude of abnormalities that may conceivably occur in a process as complex as reading. Consistent with Satz's theory, they conclude that both visual perceptual and linguistic deficiencies may be significant causes of reading disability, the presumption being that perceptual problems are characteristic of poor readers at