ATYPICAL HEMISPHERIC-SPECIALIZATION IN INTELLECTUAL DEFICIENCY

In order to determine the relation between hemispheric specialization for language and intellectual deficiency, two groups of lower-IQ subje cts were compared to normal-IQ controls on word-dichotic listening tas ks. Two conditions in which stimuli differed by their level of phonolo gical complexity were used. Normal controls showed the expected right- ear advantage in both conditions. Moreover, they showed a greater magn itude of ear difference on the condition requiring higher-order phonol ogical processing. In the mentally deficient group, almost half the su bjects exhibited a left-ear advantage and they showed no difference be tween the two conditions in terms of the magnitude of ear difference. These results point to the presence of atypical hemispheric specializa tion in mentally deficient subjects. (C) 1996 Academic Press, Inc.