The effect of concurrent manual activity on the dichotic listening performance of boys with learning disabilities.

Three groups of learning-disabled children, defined according to their Wechsler Intelligence Scale for Children (WISC) profiles, and one normal control group, were given both a standard dichotic listening task and a dichotic listening task performed concurrently with a manual tapping task. Learning-disabled children who showed no disparity in their verbal and performance subscale scores on the WISC demonstrated a right ear preference under standard testing and when tapping with the left hand, but not the right, which was nearly the same pattern as that obtained by the control group. Learning-disabled children whose verbal WISC score was at least 15 point lower than their performance demonstrated a right-ear preference only when tapping with their left hand. Finally, learning-disabled children who had high verbal, low performance WISC profiles showed no ear preference under any conditions. These results were interpreted as indicating that these three types of learning-disabled children are differentially lateralized and differentially affected by the facilitory-inhibitory effects of concurrent hemispheric activities.