Hemispheric lateralisation

• The left hemisphere is responsible for language - two main language centres: Broca's area for speech production and Wernicke's area for understanding.
• Right hemisphere is responsible for recognition of faces, places and objects and creativity and can only produce basic words and phrases but contributes to the emotional context of what is being said.
• Sperry's split brain research:

  > Severed corpus callosum to treat epilepsy

  > Natural experiment

  > Ppts sit in front of screen while fixate gaze at a spot in the middle

  > Presented with visual information for 1/10th of a second

  It was found:

  > Objects seen in right visual field can be named verbally and in writing as the image would be processed by the language centres in the left side of the brain

  > If objects are only seen in the left visual field then they can only be identified though pointing but cannot be named by the participant
• Split brain research AO3

  :) Scientific methods

  :( Individual differences

  :( casual relationship is hard to establish

  :( RTC case study EB
• Hemispheric lateralisation AO3

  :) RTS Sperry

  > Split brain patients with a severed corpus collosum

  > He found that when participants were shown an image of an object to their right visual field, the patient could name it verbally but when presented to the left visual field they could not name it verbally but could identify the object through pointing

  > the hemispheres are responsible for different functions such as the left being responsible for language abilities

  > Therefore, split brain research supports the theory of hemispheric lateralisation.
• Hemispheric lateralisation evaluation AO3

  :( Individual differences

  > The degree to which the corpus callosum was severed for each participant varied greatly with some having a greater disconnection between the two hemispheres than others

  > This is a weakness because the research may not be measuring the effects of lateralisation effectively which reduces the internal validity of the research

  > Therefore, research conducted on split-brain patients may not be appropriate for explaining hemispheric lateralisation
• Hemispheric lateralisation AO3

  :( RTC Patient EB

  > EB suffered from brain damage that resulted in the removal of his left hemisphere and therefore his language centres

  > Despite this, after some time EB managed to regain some of his language ability which would not be possible if the brain was completely lateralised

  > This demonstrates that language must be in more areas than just the left hemisphere, arguing against lateralisation of function in the brain