Split Brain research

• Sperry and Gazzaniga


  involving patients who experience a surgical separation of the hemispheres of the brain to allow us to find out the extent of which brain functions are lateralised

  LEFT FUNCTIONS = language eg speech

  RIGHT FUNCTIONS = visual-motor eg facial recognition
• Describe what you see (tests language)

  • with image in left visual field (right hemisphere) patients could not describe describe what was shown and reported there was nothing present
  • with image in right visual field (left hemisphere) patient could describe what they saw which demonstrates the superiority of the left hemisphere with speech and language production
• Tactile Tests

  • Objects places in left hand (right hemisphere) and left visual field they cannot see anything and when asked to pick they chose the key but are unsure as to why
  • Objects placed in right hand (left hemisphere) and right visual field they see the key and pick up the key knowing why which supports that language is on the left side
• Motor Skills test

  • When picture presented in the LVF (right hemisphere) they cannot see anything but draw a better face than the left hemisphere which demonstrates the superiority of the right hemisphere in visual motor skills
  • When picture presented in RVF (left hemisphere) they see a face and draw one but its better with the left hand even when right handed
• :) Scientific

  • As the research used a mixture of quasi experiments and clinical case studies we are able to combine quantitative and qualitive approaches. The quantitative can be analysed statistically against control groups and qualitive gives detailed descriptions from a patients case study allowed patients to describe meaning increasing the validity of claims.
  • Adds to the conscious of unity debate. Split brains demonstrate that an intact corpus collosum and interhemispheric communication isn't necessary for consciousness

  :) as it has positive application in RL
• :(Little value outside experiment

  • There is a lack of controls and they are comparing epileptic individuals with neurotypicals. Therefore, some affects could be due to difference in surgery rather than the procedure itself.
  • Also, had a small sample size as comparing 11 atypical patients who do not act the same as neurotypicals so therefore we cannot generalise to the population as a whole.
• :(Situation is unique

  • Split brain patients may initially suffer from hemispheres acting independently and then in an adaptive process one dominates, therefore findings would likely be different in real life as a person with a severed corpus collosum who had both eyes would be able to compensate for such a loss.
  • Also, language isn't restricted to the left hemisphere as Turk et al found patient JW who had damage to left hemisphere developed capacity to speak in the right hemisphere
  • Therefore, the study was a unique set of circumstances and would play out differently in real life.