Split Brain Research Into Hemispheric Lateralisation

Question 1

What is meant by hemispheric lateralisation?

Answer 1

The idea that two halves of the brain are functionally different and certain processes are controlled by one hemisphere rather than the other.

Question 2

What is the difference between localisation and lateralisation?

Answer 2

Localisation is to do with different areas of the brain whereas lateralisation is to do with the hemispheres.

Question 3

What connects the two hemispheres allowing them to interact?

Answer 3

The corpus callosum.

Question 4

What is meant by contralateral?

Answer 4

Information from the right visual field is processed in the left hemisphere and vice versa.

Question 5

What are split brain patients?

Answer 5

Individuals who have had their corpus callosum removed via a commissurotomy to help with their epilepsy.

Question 6

What was the aim of Sperry’s research?

Answer 6

To investigate the extent to which the hemispheres are specialised for functions.

Question 7

Outline the procedure of Sperrys research.

Answer 7

1. 11 split brain patients.
2. 4 conditions: describe what you see, matching words/faces, composite words and recognition by touch.
3. Pps had to focus on a cross whilst one eye was covered.
4. Describe what you see - presented with picture and asked to describe picture.
5. Recognition by touch - object placed in right or left hand and pp asked to describe object.
6. Drawing task - presented with a picture and asked to draw.

Question 8

Outline the findings of Sperry’s research.

Answer 8

1. Describing what you see: right vf - processed by left hemisphere and pp would say the word.
   Left vf - processed by right hemisphere and pp would only be able to write word.
2. Recognition by touch: object in left hand processed by right hemisphere meaning pps could identify object and pick a similar one from a hidden bag.
3. Drawing tasks: Pps could draw better with their left hands despite being right handed.

Question 9

What conclusions can be drawn from Sperry’s research?

Answer 9

1. Left hemisphere is dominant in terms of language and speech + the right hemisphere is dominant in terms of visual motor tasks.
2. Lh contains language centres, Rh contains visual-spatial centres.
3. The two hemispheres have different functions.

Question 10

Give 2 weaknesses of Sperry’s research.

Answer 10

1. No control group used - can’t compare findings.
2. Small sample - only 11pps used.

Question 11

Give one strength of Sperry’s research.

Answer 11

1. Research support.

It is assumed that the main advantage of brain lateralisation is that it increases neural processing capacity (the ability to perform multiple tasks simultaneously). Rogers et al. (2004) found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously (finding food and being vigilant for predators). Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions. This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks.

Question 12

Give one weakness of HL.

Answer 12

Opposing evidence.
Case study of JW: able to speak about info presented to both VFs.
Shows HL isn’t entirely fixed - language should only be on LH but wasn’t.
Therefore, invalid.