Split-brain research into hemispheric lateralisation AO1

• Hemispheric lateralisation


  The idea that the two halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other
• Language ability


  • For most people, it is controlled by the left-hemisphere
• Language is subject to hemispheric lateralisation
• Specialised areas associated with languages are found in one of the brain's hemispheres rather than both
• Split-brain research


  Experiments conducted by Sperry et al. to investigate whether neural processes may be organised in a lateralised way
• Commissurotomy


  Surgical procedure to separate the two hemispheres by cutting the corpus callosum and other connecting tissues
• For split-brain individuals, the main communication line between the two hemispheres was removed
• Sperry's procedure


  1. Image or word projected to right visual field (processed by left hemisphere)

  2. Same or different image projected to left visual field (processed by right hemisphere)
• In normal brain


  Corpus callosum would share information between hemispheres
• In split-brain individuals


  Information could not be conveyed from one hemisphere to the other
• Language processing


  • For most people, it is in the left hemisphere
• Object shown in right visual field

  Individual could describe it
• Object shown in left visual field

  Individual could not describe it
• Individuals could select matching object from grab-bag using left hand (linked to right hemisphere)
• Individuals could select object associated with object presented to left visual field using left hand
• When two words presented, one in each visual field, individual would select key with left hand and say 'ring'
• Right hemisphere dominant in recognizing faces
• Left hemisphere dominated in verbal description of composite face picture, right hemisphere dominated in selecting matching picture
• Left hemisphere


  • More geared towards analytical and verbal tasks
• Right hemisphere


  • More adept at performing spatial tasks and music, can only produce rudimentary words and phrases, contributes emotional and holistic content to language
• Left hemisphere is the analyser, right hemisphere is the synthesiser