sperry

• What was the aim?


  To test the effects of hemispheric disconnection in humans and to show each hemisphere has different functions
• What was the sample?


  11 people who had undergone a commissurotomy for severe epilepsy

  2 had undergone the surgery a long time ago

  9 had it more recently

  All ppnts were right handed
• What was the method?


  Quasi-experiment

  IV- presence or absence of the surgery

  DV- performance on various visual and tactile tasks
• What was the procedure? (Visual task)


  All ppnts with one eye covered fixed their gaze on a centre point on an upright translucent screen

  Visual stimuli were projected onto the screen and back-projected at 1/10th of a second or less (too fast for eye movements to process the information to the wrong visual field)

  This apparatus is a tachistoscope

  Information on the left side of the centre point was processed via the left visual field to the right hemisphere and vice versa
• What was the procedure? (Tactile task)


  Under the screen was a gap so ppnts could grab objects without seing their hands

  Objects were placed in the right or left hand or both hands

  Objects placed in the left hand were processed by the right hemisphere and vice versa
• What were the results? (Visual task)


  Information processed by one visual field could only be recognised if shown again to the same visual field

  Information shown the right visual field (left hemisphere) could be described in speech and writing with the right hand

  When info was shown to the left visual field ppnts said they couldn't see anything or just saw a flash of light

  BUT the ppnt could point with his left hand to the matching object/picture among others

  When info shown simultaneously to both visual fields eg. a $ to the LVF and a ? to the RVF ppnts could write the $ with their left hand but reported seeing a ?
• What were the results? (Tactile task)


  Objects placed in the right hand could be described in speech or writing

  But when the same object was placed in the left hand people made wild guesses or didn't know they were holding anything

  When objects were simultaneously placed in both hands and then hidden among other objects both hands could find their own objects and ignored the other hand's object

  Objects placed in one hand could only be recognised again by the same hand
• What were the results (Brain localisation)

  In right-handed people the left hemisphere is more dominant

  Language is located on the left side of the brain

  Both sides have their own memories

  Both sides are emotive but the right side is more emotive
• What were the conclusions?


  Both hemispheres have their own inner visual worlds

  Split-brain people have 2 separate streams of consciousness each with their own memories. impulses and emotions

  Split-brain people have a lack of cross-integration where the second hemisphere doesnt know what the first was doing