hemispheric lateralisation

• holistic theory

  -all areas of the brain work together

  -functions cannot be allocated to certain parts of the brain
• localisation/lateralisation

  -different areas of the brain carry out different functions

  -lateralisation: the hemispheres of the brain do different things
• left hemisphere

  -language centre

  -controls the right hand

  -controls the right visual field
• right hemisphere

  -visuo-spatial tasks

  -controls the left hand

  -controls the left visual field
• contralateral wiring

  -the brain is cross-wired

  -left hemisphere = right side

  -right hemisphere = left side
• lateralisation of vision

  -vision is contralateral (opposite sided) & ispilateral (same-sided)

  -each eye receives info from both visual fields

  -LVF of both eyes is connected to RH; RVF of both eyes is connected to the LH

  
• split brain research - Sperry & Gazzaniga (1967)

  -the corpus callosum that connects both hemispheres and lets them communicate is severed

  -done on 11 epilepsy patients

  -wanted to see how both hemispheres are specialised for functions

  -patients were presented with an image/word to the LVF or RVF. Info shown to one VF goes to the opposite H (right goes to left etc)

  -different tasks: describing what is seen; tactile test; drawing test

  -findings: if shown an image in the RVF, could describe it verbally; if shown in LVF, couldn't verbally describe it. Tactile test: if shown in RVF, could describe verbally; LVF, could select the object. Drawing task: RVF, poor drawing; LVF, clearer drawing

  -LH: language dominant

  -RH: visual-motor dominant
• roles of the hemispheres

  Left: problem solving; reasoning; language

  Right: creativity; abstract thinking; visual-motor skills
• AO3

  Strength(s):

  -supporting research used a small, niche sample of 11 ppts. Findings from this research can't be generalised and lacks population validity. BUT, a control group was used which increases the validity. Fink et al (1996) found that hemispheric lateralisation happens in connected brains. Increases the generalisability & validates the theory.

  -used a control group, compared the 11 ppts to this. D: no one in this group had epilepsy. Findings of the research might be bc of epilepsy, not split brain. Overall, decreases validity of the theory.

  -Pioneer: Sperry. First split-brain research. Enabled understanding of HL & allowed for more research. Has use.

  
  

  Weakness(es):

  -contradictory evidence: Tunk et al (2002). A patients with a damaged LH developed the capacity to speak in the RH. Decreases the validity of hemispheric lateralisation.