Hemispheric Lateralisation

• (AO1) Define hemispheric lateralisation + dominance

  Two halves of the brain function differently and that each hemisphere has a specific functions.

  
  

  Highlights the dominance of one hemisphere over the other in a particular psychological or physical function.
• (AO1) What is the left side and what is the right?

  Left side = language

  Right side = visual motor tasks

  
  

  Language is primarily localised in the left hemisphere of the brain, with areas such as Broca'a area and Wernicke's area playing key roles in speech production & comprehension.

  
  

  The left hemisphere controls the right side of the body, including the right eye, hand, and leg, while the right hemisphere controls the left side.
• (AO1) How are they connected?

  By thick bundle of nerve fibres called corpus callosum, which allows communication between them.
• (AO1) Discuss split-brain patients research

  Involved 11 patients, who had corpus callosum severed to treat epilepsy.

  
  

  During the study, a stimulus was flashing for 0.1 seconds either side of dot on middle of screen, splitting the visual field.

  
  

  Info presented to the right visual field (RVF) (right of dot) could be easily described in words, as is processed by left hemisphere, which controls language.

  
  

  However, info presented LVF could not be verbalised, with patients reporting "I saw nothing", but able to draw or pick associated objects with left hand, which controlled by right hemisphere.
• (AO3) Gender differences

  Point: Gender differences may play role in hemispheric lateralisation, particularly in language processing.

  
  

  Evidence: Research suggests that females tend to have proportionally larger areas, including B + W areas, which could explain why girls often more comfortable with talking.

  
  

  Evaluate: However, issues establishing cause & effect. It is unclear whether the size of the language centres lead to increased proficiency in speech, or if language centres grow as result of speaking more. Highlighting complexity of interpreting relationship between brain structure and behaviour.
• (AO3) L - Bio reductionism

  Point: Hemispheric lateralisation may be criticised for biological reductionism, as it overly simplifies complex human behaviour by attributing it primarily to brain structure.

  
  

  Evidence: While hemispheric lateralisation focuses on how specific brain regions contribute to functions like language, it ignores other potential influences on behaviour: social and environmental factors.

  
  

  Evaluate: By reducing behaviour solely to brain function, the approach neglects the interaction of multiple influences, limiting our understanding of the complexity of human behaviour & highlight need for more holistic perspective.
• (AO3) L - Plasticity

  Point: Hemispheric lateralisation challenged by concept of plasticity, highlighting brain's ability to compensate for lost function.

  
  

  Evidence: E.g. in the case of Jodie, who lost enter right hemisphere, the remaining left able to take on functions typically associated with right, like controlling movement = demonstrating brain's adaptability.

  
  

  Evaluate: Suggests strict hemispheric lateralisation is not always possible, as brain's plasticity allows it to compensate for damage, offering a more flexible understanding of brain function.