Y13 Biopsychology - Hemispheric Lateralisation and Split-Brain Research

Question 1

What is hemispheric lateralisation?

Answer 1

When one of the hemispheres specialises in certain things. Both hemispheres are not the same and specialise in different things.

Question 2

What is a split brain patient?

Answer 2

Someone who has had their brain split in half by severing the corpus collosum.

Question 3

What does the left side of the brain specialise in?

Answer 3

• Controls right side of the body.
• Viewing objects in right visual field.
• Language.

Question 4

What does the right side of the brain specialise in?

Answer 4

• Controls the left side of the body.
• Viewing objects in left visual field.
• Facial recognition.

Question 5

Why are split brain patients studied to investigate localisation and lateralisation of function?

Answer 5

When the corpus callosum is severed information can no longer move between the two hemispheres. Consequently, scientists can look at split brain patients to study the different roles of the two hemispheres.

Question 6

What was the method of Sperry (1968)?

Answer 6

• The study involved a combination of case studies and experiments.
• 11 participants had undergone split brain surgery because they had severe epilepsy that couldn’t be cured with medication.
• Control group was used consisting of people with no split brain.
• In one of the experiments, Ps covered one eye and looked at a dot in the centre of a screen. Then an image popped up either on the right or left of the screen quickly so that there was no time for eye movement.

Question 7

What were the results of Sperry (1968)?

Answer 7

Picture displayed to right visual field (left hemisphere) - all Ps could say or write what it was.
Picture displayed to the left visual field (right hemisphere) - Split brain Ps couldn’t say/write what they had seen but they could select a corresponding object with their left hand, even though they didn’t know why they had selected this object.

Question 8

What was the conclusion in Sperry (1968)?

Answer 8

Research shows that different parts of the brain specialise in different functions.
- Left hemisphere can convert sight into spoken and written language whereas right cannot but can still produce a non verbal response.
- Usually the info from each hemisphere can be transferred over to wherever is needs to be but in split brain patients this cannot happen.

Question 9

Evaluate Sperry (1968) - Advantages.

Answer 9

Using case studies as well as experiments meant that Sperry obtained both qualitative and quantitative data. Using both research methods also increases the validity and reliability of his research.

Question 10

Evaluate Sperry (1968) - Limitations.

Answer 10

• He only used 11 Ps. This small sample size means it is hard to generalise his results.
• Epilepsy is usually caused by brain damage and the patients have also been on medication which may have affected their brains and in turn the results. Split brain may not be the sole cause.
• ## Using experiments mean there is low ecological validity.