Initial stages of visual information processing in dyslexia.

Abstract

Four experimental tasks were employed to explore the initial stages of visual information processing in a group of dyslexic boys and in a group of normal control subjects ranging in age from 8 to 14 years. Two tasks involved visual backward masking; the other two were temporal integration tasks. The backward-masking tasks yielded evidence of slower rates of visual information processing in dyslexic children; the temporal-integration tasks yielded evidence of longer duration of visible persistence in dyslexic children. This effect was most evident in situations in which sequential stimuli impinged on the same retinal location. Some age trends in the development of these effects are noted. It is suggested that the dyslexic visual system may take an unusually long period of time to recover from the aftereffects of neural activity evoked by an inducing stimulus.