Sperry

• Background

  • In the 1940s, a treatment for epilepsy was developed called 'split-brain' surgery (commissurotomy) that included the corpus callosum being cut so that the abnormal electric compulsions could not spread through the brain
  • Sperry through that patients who had undergone 'split brain surgery' would be by in discovering what each hemisphere in the brain actually does
• Lateralization 


  One side of the brain has more function than the other
• Corpus callosum


  Fibres that carry the majority if the info between the two hemispheres of the brain
• Contralateral control


  The idea that each side of your body is controlled by opposite sides of your brain
• Commissurotomy 


  Surgical operation that severs the corpus callosum
• Visual presenting

  • in each eye we have two visual fields - left and right
  • Our left visual fields in both eyes sends info to the right hemisphere of the brain
  • Our right visual field in both eyes sends info to the left hemisphere
• Aim

  To study the functions of separated and independent hemispheres
• Sample

  • Epileptic
  • 11 patients from America who had undergone commissurotomy
  • Non-epileptic
  • They were compared to a control group of people who didn't have epilepsy
• Controls

  • Symbols displayed
  • Images displayed
  • Objects used
  • Fixation point
  • 1/10 second presentation time
  • Hands out of view
  • One eye covered
  • Tachistoscope
• Objects presented in RVF

  • Info went to the left hemisphere
  • Participants could describe it in speech and writing
  • Left hemisphere can communicate anything from RVF
• Objects presented in LVF

  • Info went to the right hemisphere
  • If asked to point to an object with their left hand that matched they could
  • They insisted they couldn't see anything
  • Right hemisphere does not have language ability
• Diff stimuli presented to diff visual fields

  • Right hemisphere - apple
  • Left hemisphere - key
  • Able to draw an apple but not know why
  • Able to say they had see the key
• Simple maths to LVF

  • Info goes to right hemisphere
  • Were able to sort objects by shape, size and texture - only using their left-hand
  • Right hemisphere can process math problems
• Nude image to LVF

  • Info went to right hemisphere
  • Participant would giggle / look embarrassed when nude image appeared
  • They could not say why they were embarrassed
  • Non-verbal response suggests right hemisphere has second conscious entity
• Conclusion

  • Study supports the idea the brain consists of two independent hemispheres, each with its own consciousness that don't communicate
  • The dominant hemisphere was the left-hand side which contains the speech centres