Variability in right hemisphere language function after callosal section: evidence for a continuum of generative capacity.

Two recent patients in our behavioral series investigating the psychological effects of callosal section exhibit right hemisphere language. Using lateralized visual and auditory stimulation, semantic, phonetic, and expressive linguistic functions were examined. While the right hemisphere language systems in both patients were shown to be capable of semantic information processing, they differed in their abilities to process phonetic information, follow verbal commands, and produce linguistic responses. It is argued that the differences between left and right hemisphere language systems are quantitative and are best characterized along a continuum of generative capacity. It is the variability in such capacity that appears to be responsible for the variability in right hemisphere language function within the split-brain population.