Split-brain research into hemispheric lateralisation

  • Split-brain research:
  • AO1: 
  • Hemispheric lateralisation concerns behaviours controlled by just one hemisphere. Language is an example of hemispheric lateralisation (usually) controlled by the left hemisphere. 
  • Sperry sought to deomonstrate that the 2 hemispheres were specialised for certain functions and could perform tasks independently of one another. Normally the hemispheres are connected by the corpus callosum and a few other structures. A commissurotomy is an operation to cut the corpus callosum and is sometimes performed to control epileptic seizures. Sperry studied a group of epileptics who had the operation. 
  • Sperry devised a unique procedure to test his split-brain patients. An image or word is projected to a patient's RVF (procesed by LH) and another image to the LVF (processed by RH). In a normal brain, the corpus callosum 'shares' information between both hemispheres. In split brain, the information cannot be conveyed from the chosen hemisphere to the other. 
  • The object shown to RVF - petient easily describes what is seen. When shown the LVF - patient says there is nothing there. They can't describe the objects in LVF because RH usually lacks language centres. Messages recieved by RH are normally relayed via the corpus callosum to language centres in LH. 
  • Objects shown to LVF: couldn'y name them but could select a matching object using left hand (connected to RH recieving info from LVF). Left hand could also select an object that was associated with the image presented to the LVF (ashtray selected in response to a picture of a cigarette). In each case, the person couldn't verbally identify what the had seen (because LH os needed for this) but could 'understand' what the object was (using the RH) and


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