A03

• What are the strengths of hemispheric lateralisation?

  1. Related to increased neural capacity
  2. Scientific methodology
• What are the limitations of hemispheric lateralisation

  1. Differences in function may be overemphasised
  2. Lateralisation changes with age
• Strength = related to increased neural capacity

  • By using only one hemisphere to engage in a particular task this would leave the other hemisphere free to engage in another function and thus increasing neural processing capacity
  • e.g. Rogers et al. (2004) - in the domestic chicken, brain lateralisation is associated with enhanced ability perform two tasks simultaneously (finding food and being vigilant for predators)
• Strength = scientific methodology

  • Experiments involving split-brain patients made use of highly specialised and standardised procedures
  • There was a high degree of control over all variables, increasing the internal validity of the experiment
• Limitation = differences in function may be overemphasised

  • Sperry’s work tends to overemphasise and oversimplify the functional distinction between the left and right hemispheres
  • Modern neuroscientist -> the actual distinction between left and right hemisphere is less clear-cut
  • In the normal brain the two hemispheres are in constant communication when performing everyday tasks and many of the behaviours can be performed by both
  • e.g. Patient J.W. developed the capacity to speak out the right hemisphere
  • Challenges claim right hemisphere is unable to handle language
• Limitation = lateralisation changes with age

  • Lateralisation of function appears to not stay the same throughout a lifetime, but changes with normal ageing
  • Szaflarski et al. (2006) -> found language became more lateralised in the left hemisphere with increasing age in children and adolescents but after the age of 25 lateralisation decreased with each decade across life
  • Across many types of tasks and many brain areas lateralised functions found in younger individuals tend to switch to bilateral functions in healthy older adults
  • Implies lateralised brain not true for all ages