HEMISPHERIC CONTRIBUTIONS TO THE INTEGRATION OF VISUAL AND AUDITORY INFORMATION IN SPEECH-PERCEPTION

Differential hemispheric contributions to the perceptual phenomenon kn own as the McGurk effect were examined in normal subjects, 1 callosoto my patient, and 4 patients with intractable epilepsy. Twenty-five righ t-handed subjects were more likely to demonstrate an influence of a mo uthed word on identification of a dubbed acoustic word when the speake r's face was lateralized to the LVF as compared with the RVF. In contr ast, display of printed response alternatives in the RVF elicited a gr eater percentage of McGurk responses than display in the LVF. Visual f ield differences were absent in a group of 15 left-handed subjects. Th ese results suggest that in right-handers, the two hemispheres may mak e distinct contributions to the McGurk effect. The callosotomy patient demonstrated reliable McGurk effects, but at a lower rate than the no rmal subjects and the epileptic control subjects. These data support t he view that both the right and left hemisphere can make significant c ontributions to the McGurk effect.