Sperry

• Background to study:

  • previous research using split brained animals showed numerous behavioural effects
  • recent research by Sperry using appropriate tests shown a large number of behavioural effects that correlate directly with the loss of neocortical commissures in man as well as animals
• Aim: To investigate the effects of hemispheric deconnection on perception and memory. To demonstrate that hemispheres have different functions/abilities and each hemisphere has it's own conscious awareness and memory
• Research method:

  • quasi/natural experiment
  • conducted in lab conditions - variables controlled
• IV: participants having a split brain or not
• DV: participant's ability to perform a variety of visual tactile tests
• Sample: 11 patients who had undergone split brain surgery
• Method:

  • took part in a series of tactile, visual and auditory tests
  • visual test - non tested eye was covered & only 1 visual field was presented with stimuli
  • stimuli for each test were 35 millimetre transparencies and began with a fix gaze on a centre line, and presenting stimuli for 1/10 of a second
• Results:

  • information shown in 1 visual field could only be recognised in that visual field
  • information presented to the Right Visual field (Left Hemisphere) could be described in speech & writing. if same info was presented to the Left Visual field (RH) participant insisted he didn't see anything or there was only a flash of light. could point with left hand to a matching picture/object presented among a collection of pictures/objects
• Results pt2:

  • objects felt by one hand only recognised again by the same hand
  • when 2 objects were simultaneously in each hand & then hidden in a pile of objects, both hands selected their own object and ignores the other hand's object
• Conclusion:

  • people with split brains have two separate visual inner worlds, each with its own train of visual images
  • Split-brain patients have 2 independent streams of consciousness, each with its own memories, perceptions and impulses
  • split brain patients can perform simple simultaneous tasks controlled by each hemisphere better than non split brain