A2 Biological Psychology

Hemispheric Lateralisation

Brain has two hemispheres which are connected by the corpus collosum, a bundle of fibres and is a communication pathway, so the two hemispheres can communicate with each other

The brain is contralated, so the left side deals with the right hand side of the body, and the right side deals with the left hand side, and different functions are dominant in each hemisphere.

• Left Hemisphere - Broca's and Wernicke's area ony found here (language functions/processing), logic, analysis, and problem solving
• Right Hemisphere - Recognises others emotions, spatial comprehension, emotions, face recognition and creativitiy

Localistation of Function

Certain areas of the brain are thought to be responsible for particular function, e.g. vision, language, coordination.

1) Motor Cortex - Voluntary (complex) movement, sends messages to the muscles via brain stem and the spinal cord.

2) Somatosensory Cortex/ Centres - lies next to the motor cortex, processes information about touch, pain, temperature and proprioception (position of body). Areas such as the face take us a larger proportion as the face contains more neural connections.

3) Visual Centres (Primary Visual Cortex) - 2, one in each hemisphere. In the ocipital lobe at the back of the brain, this is the main visual centre, dealing with sight and visual perception, information from the eyes.

4) Auditory Centres (Primary Auditory Cortex) - 2, one in each hemisphere. This recieves information from both ears via two pathways, about where the sound is and what it is, information from the ears.

Languages Centre: 5) Broca's area - responsible for the production of speech. 6) Wernicke's area - responisble for understanding language

Split Brain Research (Sperry 1968) - lacteralisation of function

• A - Investigate the effects of cutting the corpus callosum from epilepsy patients, looking at behaviour, perception of objects, hemisphrere roles)
• M - Case studies - epilepsy patients
• Interviews
• Experiments where colours are shown to just the left visual field, and just the right = detected by the opposite hemisphere
• Experiments using familar and unfamilar tasks
• F - Unfamilar tasks (stringing beads), can't be performed, but familar tasks (tying shoe laces) could
• Few weeks after surgery, hemispheres act seperately = person can feel like 2 different people in one body, then the left hemisphere takes control
• Hemispheres co-operate and compensate (e.g. blue colour shown to the left will be seen by the right)

Evaluation

• Not all research shows the brain compensates and communicates - other cases the 2 hemispheres compete with each other = individual feeling that parts of their body don't belong to them
• Cause and Effect - can't be certain how the brain was functioning beforehand (damage - seizures) = can't be certain the effects are due to split brain
• Only 10-15 patients properly studied - hard to generalise conclusions from a small sample, and very few of these are a varied group (different in age, gender) = difficult to draw conclusions
• Operations are not comparable - In addition to the corpus callosum, lots of smaller pathways may or may not been cut…