one brain or two?. roger sperry & michael gazzaniga rare and extreme cases of epilepsy, radical...
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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 testPicture shown to one visual field
Tactile testFeel but not see object
Auditory testTold to reach in bag and find asked for object
ResultsVisual test –
Right visual field, said object
Left visual, saw nothingWhen 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
CriticismsJarre 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.