Lateral asymmetry in perceptual judgments of reading disabled, hyperactive and control children.

Three groups of 11 year old boys, classified as reading-disabled/hyperactive, hyperactive, and normal controls, made same-different judgments to pairs of verbal or visuospatial stimuli presented simultaneously to the right or left side of a fixation point. Two experimental paradigms were used, one emphasizing comparison judgments from memory, the other, new comparison judgments. Reading-disabled boys made more errors of judgment than did controls. All subjects exhibited faster reaction times for different judgments of pairs appearing in the left visual field. Reaction times were longer and errors more numerous for judgments made when two stimuli were presented simultaneously, one to each visual field. Differences in performance for the two halves of the visual field are attributed to memory storage effects for overlearned stimuli. The deficiency in interhemispheric comparisons is attributed to immaturity of the cerebral commissures. The reading-disabled group appears to encompass two subgroups with differing modes of information processing.