SEMANTIC NETWORKS IN THE DIVIDED CEREBRAL HEMISPHERES

Hemispheric differences in the recognition and manipulation of meaning may be based on distinctions in size, composition, or organization of the right and left semantic networks. The present study describes the se features of pictorially based semantic networks in 3 subjects with complete forebrain commissurotomy. Stimuli were presented for prolonge d viewing to the left and right visual hemifields. For each trial, the subjects chose from a 20-choice array all pictures that were associat ed with a target, then indicated the member of each pair of chosen ass ociates that was more closely related to the target. The hemispheres' network were found to be of similar size and composition, but were org anized differently. The right hemisphere more often produced linear ra nkings of semantic associates to a target than did the left, and ranki ngs by the two hemispheres were nor strongly correlated. Hemispheric d ifferences in semantic organization mirror differences in perceptual o rganization, with the right hemisphere specialized for conventional me aning and the left hemisphere specialized for detecting and processing deviations from standard meaning.