PAPER 2 - Biopsychology - Split brain research into hemispheric lateralisation

Question 1

How does the research of Broca and Wernicke provide evidence for hemispheric lateralisation?

Answer 1

Broca - studies 8 patients who all had lesions in the left frontal lobe (Broca’s area) and had problems producing speech.
Wernicke - his patients had lesions in the left temporal lobe (Wernicke’s area) and had problems understanding speech.
= language is lateralised to the left hemisphere.

Question 2

Evaluate the strength that split brain research is highly scientific.

Answer 2

The experiments had remarkably controlled procedures - seen in how highly specialised and standardised the procedures were.
e.g. Sperry presented the information for 1/10th of a second = the split-brain patient would not have the time to move their eye across the image and spread information across both sides of the visual field = ensure only one hemisphere received info.
= highly replicable and can be easily adapted.

Question 3

Evaluate the limitation that split brain research contains a high amount of extraneous variables.

Answer 3

1. Variation in disconnection…the extent that the CC had been cut varied across patients.
2. Lack of a valid control group…all split-brain patients had suffered from epileptic seizures whereas control group had no history of this = not a direct comparison.
3. Drug therapy…some patients had experienced varying lengths and dosage of drug therapy for their epilepsy than others.

= undermines what we can learn about hemispheric lateralisation from this split-brain research.

Question 4

Evaluate the limitation that split brain research lacks generalisability.

Answer 4

Such a small and unique sample = cannot be representative of the wider population = the research is limited in its ability to tell us about hemispheric lateralisation as it’s lacking in population validity.

Question 5

Evaluate the limitation that split brain research produces contradictory findings.

Answer 5

Gazzaniga - “The Split-Brain Revisited”
Reported that Patient J.W. had developed the capacity to speak out of his right hemisphere…courtesy of brain plasticity (the brains ability to change and adapt)