One Brain or Two?

Roger Sperry & Michael Gazzaniga Rare and extreme cases of epilepsy, radical but effective treatment – cut the corpus callosum Of 10 operations, 4 subjects agreed to further testing

Three Types of Tests Visual abilities test Tactile test Auditory test Picture shown to one visual field Tactile test Feel but not see object Auditory test Told to reach in bag and find asked for object

Results Visual test – Tactile test – Vicki Right visual field, said object Left visual, saw nothing When asked to point to object in left field, did so with right hand Conclusion: both “brains” see the object, only left hemisphere has language skills to say what they saw Tactile test – Object in right hand, could say Object in left hand, couldn’t say what it was They could point to the same object from group in front of them Vicki

Criticisms Recent Applications Jarre Levy Disputes pop culture ideas of being right-brained or left-brained Two hemispheres necessary to do practically everything Recent Applications As above, attempts to clarify the misunderstandings and misapplications Schiffer (1996) – hypothesized that MPD person has more-than-usual level of independence in one hemisphere, takes ‘control’ of consciousness, etc.