Hemispheric Lateralisation

Question 1

Split-brain studies

Answer 1

-Sperry 1968 involved a unique group of individuals who all underwent the same surgical procedure.

-This is where the corpus callosum and other tissues were cut down the middle in order to separate the two hemispheres and control frequent and severe epileptic seizures

-This allowed Sperry to see the extent to which the two hemispheres performed tasks independently of one another

Question 2

Procedure of Split-brain

Answer 2

-Devised a general procedure in which an image or word could be projected to a individual’s right visual field and the same, or different image could be projected to the left visual field.

-In the ‘normal’ brain, the corpus callosum would immediately share info between both hemispheres giving a complete picture of the visual world.

-However, showing the image to one hemisphere with split-brain meant that info could not be conveyed to the other hemisphere

Question 3

Findings of Split-brain

Answer 3

When their right eye was covered and the lights were flashed to the left side of their visual field they claimed not to have seen any lights at all.
However, when asked to point at which lights had lit up they could do

Question 4

Conclusion of Split-brain

Answer 4

This shows that ppts had seen the lights in both hemispheres but that material presented to the left eye could not be spoken about as the right hemisphere has no language centre and thus cannot speak about the visual info it has received.
It can communicate about this in different non-visual ways, however ppts could point at what they had seen

This proves that in order to say that one has seen something the region of the brain associated with speech must be able to communicate with areas of the brain that process visual info

Question 5

A03- Demonstrated brain functions

Answer 5

P=There is research support for lateralised brain functions.
E=Research conducted have found that the left hemisphere is more geared towards analytic and verbal tasks, and the right was better performing spatial tasks and music
E=This suggests that the left hemisphere is the analyser whilst the right hemisphere is the synthesiser

Question 6

A03- Strengths of the methodology

Answer 6

P=Research into split brain had very good control
E=Research conducted used standardised procedures. Psychologist would flash images and ask ppt to focus at on a given point. This would not allow split-brain patients to have time to move their eyes across the image and so spread the information across both sides of the visual field.
E=Thus eliminating external variables, ensuring that only one hemisphere was receiving information at time
Therefore it can be said that Sperry developed a very useful and well-controlled procedure

Question 7

A03- Issues with generalisation

Answer 7

P=It can be argued that much of split-brain research may present issues with generalisation
E=There were 11 who took part in all variations of the basic procedure however all had a history of epileptic seizures
E=It can be said that these seizures have caused unique changes in the brain that may have influenced more disconnection of the two hemispheres