Biopsychology: Hemispheric lateralisation and split-brain research

Question 1

What is the brain split into?

Answer 1

The left and right hemispheres

Question 2

What are the two hemispheres connected by and what does it do?

Answer 2

The corpus callosum - acts as a bridge between the two hemispheres and allows them to send messages and work together

Question 3

Where are the 2 main centres for language located?

Answer 3

Left hemisphere:
Broca’s area= left frontal lobe
Wernicke’s area= left temporal lobe
- so language is lateralised (performed by one hemisphere)

Question 4

The LH controls movement on what side of the body?

Answer 4

Right side of the body

Question 5

Is vision lateralised?

Answer 5

No

Question 6

How does vision work?

Answer 6

1. Each eye receives light from LVF and RVF
2. LVF of both eyes= connected to RH
3. RVF of both eyes= connected to LH
4. This enables the visual areas to compare the slightly different perspective from each eye and aids depth perception

Question 7

What does a split brain operation involve?

Answer 7

Severing the connections between RH and LH, mainly the corpus callosum

Question 8

What is this surgical procedure commonly used for?

Answer 8

Reducing epilepsy

Question 9

Who did research into split brain?

Answer 9

Sperry

Question 10

What was the AIM of Sperry’s research?

Answer 10

AIM:

• To see how the two hemispheres deal with, in this case, speech and vision

Question 11

What was the PROCEDURE in Sperry’s research?

Answer 11

PROCEDURE:

• 11 people who had split-brain operations were studied
• meant that info could not be communicated between the 2 hemispheres
• An image was projected to RVF (processed by LH) & same/different image projected to LVF (processed by RH)

Question 12

What was the RESULTS of Sperry’s research?

Answer 12

RESULTS:

Picture of object shown to RVF= participant would describe what was seen
Picture of object shown to LVF= participant said nothing was there but could select matching objects out of sight using left hand (linked to RH)

Question 13

What was the CONCLUSION of Sperry’s research?

Answer 13

CONCLUSION:

• show how certain functions are lateralised in the brain
• support view that LH is verbal and RH is ‘silent’ but emotional

Question 14

EVALUATION: Split brain research
(one strength/ one limitation)

Answer 14

Strength: Research support
- has been supported by more recent split-brain research
- e.g. Luck et al showed split-brain participants actually performed better than connected controls on certain tasks
- they were faster at identifying the odd one out in an array of similar objects than normal controls
- In the normal brain, the LH better cognitive strategies are ‘watered down’ by the inferior RH
- supports sperry’s earlier findings that the ‘left brain’ and ‘right brain’ are distinct

Limitation:
- Small sample was used
- hard to generalise these findings to wider population (their brains may be abnormal in other ways)
- comparison group used by Sperry were not people with a history of epileptic fits (so not a valid comparison)