Hemispheric specialization for the processing of tactual stimuli in congenitally deaf and hearing children.

A group of congenitally deaf and a group of normal hearing children were given two dichhaptically presented tests of hemispheric specialization. Left hemisphere specialization for language was assessed by a letter sequences task and right hemisphere specialization for spatial stimuli was measured by the nonsense shapes test of Witelson (1974). The results showed a significant right tactual field superiority for the processing of tactually presented letter sequences. There were no significant differences between the tactual fields for the processing of tactually presented nonsense shapes. The pattern of lateralization demonstrated on the letter sequences task was consistent across both groups. However, groups differed significantly on the overall performance of the verbal task, with deaf subjects demonstrating lower accuracy scores compared to hearing subjects. Age and I.Q. factors produced significant differences between sub-groups on the nonsense shapes task.