hemispheric lateralisation

Question 1

what is hemispheric lateralisation

Answer 1

• the idea that the 2 halves of the brain are functionally different, and each has its functional specialties
• the hemispheres are connected by nerves fibres called corpus callosum, which facilitate interhemispheric communication

Question 2

split brain research - speedy and gazzaniga

Answer 2

used 11 patients who had their corpus callosum cut to treat their severe epilepsy in order to examine the extent that the 2 hemispheres are specialised for specific functions

Question 3

split brain research - method

Answer 3

an image or word was presented to the left or right visual field. patients were asked to either describe what they saw, draw what they saw, or when placed in either hand they had to describe it or pick a similar object from a group

Question 4

split brain research - results

Answer 4

• pictures presented to the right visual field could be described and drawn with the right hand but not clearly. when presented to the left visual field the picture couldn’t be described but the left hand drew the picture clearly.
• objects placed in the right hand could be described and a similar object could be selected. when placed in the left hand they could not describe it but a similar object could be identified

Question 5

split brain research- conclusion

Answer 5

the left hemisphere is dominant in speech and language, whereas the right hemisphere is dominant in visual motor tasks

Question 6

give a strength of split brain research
1/2

Answer 6

brain lateralisation increases the capacity for neural processing, the ability to perform tasks simultaneously. rogers et al found in domestic chickens that brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously. this is because using one hemisphere to complete a task leaves the others to engage in other functions. this research supports the advantages of brain lateralisation in enhancing efficiency in cognitive tasks

Question 7

give a strength of split brain research
2/2

Answer 7

sperry’s research was highly controlled and scientific, making it reliable and valid

Question 8

give a limitation of split brain research
1/2

Answer 8

sperry used a sample of 11 patients with severe epilepsy who had undergone surgery to have their corpus callosum cut. this means that the study lacks population validity, as this sample isn’t generalisable and results and conclusions can’t be applied to the wider population. we cannot assume that people without epilepsy for example would respond in the same way to these tasks. consequently, more research is required. furthermore, since very few people ever undergo split brain surgery, so the research often takes an idiographic approach, making universal laws based on limited samples.

Question 9

give a limitation of split brain research
2/2

Answer 9

it’s been argued that language isn’t specific to the left hemisphere. turk et al found a patient who had damage to their left hemisphere but had developed the ability to to speak in the right hemisphere, eventually being able to speak about information presented to either side of the brain. this suggests that lateralisation perhaps isn’t fixed and that the brain can adapt following damage, reducing its validity