LOW-LEVEL VISUAL PROCESSING SKILLS OF ADULTS AND CHILDREN WITH DYSLEXIA

Previous work by Lovegrove and colleagues (Lovegrove, Martin, & Slaghu is, 1986) suggested that dyslexic children show visual deficits specif ic to transient processing. We designed and examined a number of thres hold and suprathreshold tasks to test the generality of their claims. We first compared the performance of adult dyslexics and child dyslexi cs to the performance of age-matched normal readers on a series of thr eshold flicker tasks. In contrast to the earlier results, dyslexics an d normal readers did not differ in their contrast thresholds for flick ering sinewave gratings. Dyslexic children and normal readers also sho wed similar performance on two suprathreshold visual search tasks that evaluated transient processing. The evidence suggests that a transien t processing deficit is not a general characteristic of developmental dyslexia. Claims that visual factors play a role in dyslexia must addr ess the confounding role of performance and attentional factors.