Biopsychology -Split brain research

Question 1

Define contralateral

Answer 1

Each hemisphere of the brain controls the opposite side of the body

Question 2

What is the corpus callosum

Answer 2

Thick bundle of 200-300 million nerve fibres (White matter) connecting the left and right hemispheres

Question 3

What did Sperry do?

Answer 3

Research study on 11 patients who had their corpus callosum cut to treat epilepsy

Question 4

Explain Sperry’s procedure and findings

Answer 4

• Conducted a quasi-experiment comparing 11 patients who had undergone corpus callosotomy
• Sperry controlled the information that each hemisphere had access to
• Participants were required to either say what they had seen, draw the object or select from objects that were hidden from view with their hands.
• Sperry found that info presented to the LH could be spoken, but not spoken if delivered to RH. However RH could draw or select object using their left hand. Suggesting that both hemispheres are capable of acting independently. also supporting the theory that language centres are in the left side of the brain.

Question 5

What did Gazzaniga find?

Answer 5

Found that when each hemisphere of split brain patients were presented with faces the RH was much more able to recognise them. Suggesting that the RH is specialised for facial recognition.

Question 6

Limitations of sperry’s research

Answer 6

• Small sample size of split-brain patients, participants were compared against non-epilectics (not valid comparison), had varying amount of connection cut away and had all undergone drug therapy. Suggests some of the results may have been due to participant variables making the results ungeneralisable to the wider population.
• Experimental procedure used in split brain patients is unlike how these individuals would process information and act in normal day to day life. Resulting in low external validity (tasks lack mundane realism). In real life both hemispheres would have access to info by moving the head.
• 10 men and 1 woman so studies cannot be generalised to women

Question 7

Strength of sperry’s research

Answer 7

+ Research has had a fundamental impact on the psychological and philosophical understanding of both the unity of consciousness and identity. Suggests that the brain is a combination of separate intelligent processes working together

+ Clearly demonstrated lateralisation of function = SBR was pivotal in establishing the differences in functions between the two hemispheres, and so opposing the holitsic theory of brain . LH was demonstrated as being dominant for language tasks due to containing language centres, whereas the right hemisphere was demonstrated as being dominant for visuo-spatial tasks. Suggests that the LH is the anayser whereas the right hemisphere is the synthesiser, and so there are marked differences between the two.

+ Conducted in a laboratory setting and therefore Sperry had high control over extraneous variables .