hemispheric lateralisation

• what is hemespheric lateralisation?

  • some mental processes are specialised in one hemisphere only e.g. language
  • each hemisphere has its own functional specialisations
  • LEFT: speech and language
  • RIGHT: visual- motor tasks
  • the hemispheres are connected by the corpus callosum (a bundle of nerves)
  • allows interaction and transfer of information
• hemispheric lateralisation strenghts

  • increases neural processing capacity
  • by only using one hemisphere to engage in a task, the other hemisphere is free to engage in a idfferent function
  • ROGERS found in the little domestic chicken that lateralisation is associated with an enchamced ability to perfrom two tasks at once
• hemispheric lateralisation strengths

  • RILEA found no sex differences in all categories investigated which demonstrates how the dominant hemispheres arent as dominant as one thought
• split brain research aim

  • SPERRY AND GAZZANIGA
  • tested the capabilities of the separated hemispheres by sending visual info to just one hemisphere
  • becasue the right hemisphere receives info from the left
• split brain research procedure

  • SPERRY AND GAZZALINGA
  • 1. patients fixate on a dot in the middle of a screen, their hands are under the table and out of sight
  • 2. imagfe appears in either left or right visual field and asked to respond
  • left hand response (controlled by right hemisphere)
  • verbal response (controlled by left hemisphere)
  • e.g. patient sees a dog in left visual field 'i saw a dog' as left hemisphere controls right visual field and has language centre and sees a cat in the left ' i see nothing'
  • right hemisphere controls left visula field but has no language centre
• split brain research results

  • SPERRY AND GAZZANIGA
  • left hemisphere is responsible for speech and language
  • right hemisphere is responsible for visual spatial processing and facial recognition
  • connectivity between the hemispheres are as important as localised regional functions
• split brain research strength

  • scientific - produced large amount of research findings
  • strong, scientific methodology
• split brain research limitations

  • quantitative data
  • very few people undergo severing their corpus callosum and even less in modern time
  • confounding variable - language isn't restricted to the left hemisphere
• how was SPERRY and GAZZANIGA'S research limited

  • by the small sample size of split-brain patients
  • there was very few people who had there corpus callosm severed
  • e.g. some patients had been disconnected for longer and the bran would have experienced different degrees of adaption to loss of functions