Sperry

• background 


  • Sperry had investigated the role of the two hemispheres in cats and monkeys which had their two hemispheres surgically cut
  • by training these animals, he found that you could teach one hemisphere of the brain a task while the other was unaware of the information learned, suggesting that the brain is made up of two separate modules
• aim


  • Sperry aimed to investigate the function/abilities of each hemisphere of the brain
  • He also wanted to investigate the effect of de-connecting the two hemispheres of the brain
• sample


  • 11 male and female patients who had had a commissurotomy (split brain surgery) in order to treat their epilepsy
• procedure


  each participant took part in two tasks:

  • a visual task: participants sat down in front of a machine covering one eye (only one visual field). they stared at a fixation point while images were flashed on for 1/10th of a second. they were asked to name, draw or point to the object
  • a tactile task: participants sat down with their hands shielded from view. they were asked to pick up objects with one hand from behind the screen. they were then asked to name, point or pick up the object again
• results


  • the left hemisphere of the brain controls the right side of the body and the right visual fields
  • the right hemisphere of the brain gets information from the left side of the body and the left visual fields
  • the left hemisphere of the brain controls language ability
• conclusions


  • with the corpus callous cut, one side of the brain does not know what the other side is doing
  • there is a lateralisation of brain function: each side of brain has its own specialised roles
  • left hemisphere controls speech, writing, language and right visual field of both eyes
  • right hemisphere controls the left side of the body and is able to communicate information presented non-verbally