Speech without conscious awareness.

Following commissurotomy, it is usually the case that information presented to the left hemisphere can be named and described, while information presented to the mute, right hemisphere cannot be spoken about. In the present study, it was discovered that under special test conditions, an MRI-verified, callosally sectioned adult could name or write about information presented to the right hemisphere. Studies revealed this was not an instance of right hemisphere expression. Rather, the right hemisphere was somehow able to program the left hemisphere for a spoken or written response. Further, the studies also showed that the left hemisphere was not consciously aware that it possessed the information transmitted to it by the right half brain.