Hemispheric lateralisation

• The cerebrum is divided into two semetrical halves or hemispheres
• The corpus connects the two brain hemispheres and allows them to coordinate functions
• Lateralisation is when specific brain hemispheres have control over specific functions
• EG of lateralisation; the right hemisphere control facial recognition while the left contains Broca and Wernicke's areas (Language production and comprehension)
• The right hemisphere is known as the analyser while the left is known as the synthesiser
• Lateral wiring is activity on the left side of the body being controlled by the right side of the brain and vice versa
• Vision is an example of a non-lateralised function
• vision is contre-lateral as both eyes receive information from the opposite visual field
• Vision is ipsilateral with information from both eyes regarding the right visual field going to the left side of the brain and vice versa
• Split brain patients are individuals who have had a commissurotomy; an operation in which the corpus callosum is cut preventing the hemispheres from coordinating functions
• Sperry (1968) aimed to display how the two brain hemispheres deal with speech and recognition
• Sperry (1968) used a sample of 11 split brain patients along with a control group
• Sperry (1968) would project and image to a participants left visual field or their right visual field
• Sperry (1968) asked participants to describe the object they were seeing and select a matching object from items in front of them
• Sperry (1968) found that objects shown to the right visual field were easily processed by the left hemisphere allowing them to be described but were not processed by the right hemisphere so no matching object could be chosen
• Sperry (1968) found that objects shown to the left visual field were easily processed by the right hemisphere allowing a matching object to be chosen but were not processed by the left hemisphere so could not be described
• Sperry (1968) strength: standardised procedure as participants would look at a fixed point with one eye while the image flashed of 0.1 seconds to ensure the other eye would not see it and spread it to the other hemisphere of the brain improving reliability HOWEVER the procedure used a highly artificial task reducing the mundane realism of the study and therefore its ecological validity
• Hemispheric lateralisation weakness; the theory of brain plasticity contradicts hemispheric lateralisation as it displays that the brain can change its structure and function so if an area on the left hemisphere is damaged the right can take over from it EG if Broca's area is damaged the right hemisphere can take over its functions
• Hemispheric lateralisation weakness; split brain research is difficult to generalise as it uses split brain patients who have abnormal brain function so research into them may not fully reflect that of the general population and how their brain hemispheres interact making the research idiographic as it only applies to very extreme cases so it would be rejected by psychologists following a nomothetic approach