Background * Right and left hemispheres mirror each other, there are distinct areas dealing with speech production and comprehension showing their functional localization. It exists because Broca’s and Wernike’s areas are only found in left hemisphere. * Primary cortex is situated in frontal lobe; areas in right hemisphere receive information from and are concerned with activities on left side of body. * Sperry believes studies involving split-brain patients reveal ‘true’ nature of two hemispheres because commissurotomy disconnects the two hemispheres. This means they only work independently. * Previous research on animals showed behavioral effects. * Other research by Sperry on humans and monkeys suggested the behavioral effects of the surgery might be less severe than other forms of cerebral surgery, e.g. frontal lobotomy. * Akelaitis (1944) found that there were no important behavioral effects of surgical section of corpus callosum in humans, provided other brain damage was excluded. Research Method Aim and Hypothesis * Aim of the study was to investigate if each brain hemisphere: (i) Possesses an independent stream of conscious awareness (ii) Has its own separate chain of memories that are inaccessible to the other Method/Design/IV & DV/ Controls * Quasi experiment * IV- having a split brain or not * DV- participants ability to perform a variety of visual and tactile tests * Argued that because such extensive tests were carried out on a very small sample this study can be considered a collection of case studies Participants * 11 patients who had undergone the surgery * First patient had his surgery 5 and a half years before study was conducted, second patient had her surgery more than 4 years before the study was conducted, the other 9 patients had their surgery at varying times before the study was conducted. Materials/ Apparatus * Tachistoscope/ 35-mm transparencies/ a standard projector/ visual and tactile tests (objects) Procedure * Participant centered his gaze on fixed point in the center of an upright translucent screen. Visual stimuli on 35 mm transparencies arranged in standard projector, then back-projected at 1/10 of a second (too fast for eye movement) * Everything projected on left of central meridian of screen passed via left visual field to the right hemisphere, and vice versa * Presenting tactile information * Below screen, was a gap so that participants could reach objects but not see their hands. Info about objects placed in left hand is processed by right hemisphere, etc. * Undertook variety of visual and tactile tests, this is called a ‘tachistoscope’

Results

Discussion

* Commissurotomy has prevented both hemispheres from communicating. The right hemisphere appears to not have the ability to use language, so communicates independently with outside world by moving the left hand. The left hemisphere has language ability, so therefore can read and talk.

Conclusion

* People with split brains have two separate visual inner worlds, each with its own visual images * They have a lack of cross-integration where the second hemisphere doesn’t know what the first hemisphere has been doing * They have two independent streams of consciousness, each with its own memories, perceptions and impulses.