hemispheric lateralisation and split-brain research

Question 1

what does hemispheric lateralisation mean

Answer 1

the brain is lateralised ie. it has two sides (hemispheres)
The two halves of the brain are functionally different and certain processes are controlled by one hemisphere.
The term lateralisation refers to the fact that two halves of the brain are not entirely alike. Each hemisphere has functional specialisations ie. research has found that the left hemisphere is dominant in language and speech whereas the right hemisphere excels at visual motor tasks.
Paul Broca established that damage in one particular area of the left hemisphere resulted in language deficits, whereas damage to the same area on the right brain hemisphere did not have the same consequence.

Question 2

functions of left and right hemisphere

Answer 2

left - langauge
right - drawing, spatial ability, facial recognition

Question 3

if language is located in the left hemisphere, how can we talk about things that are experienced in the right hemisphere eg. face recognition

Answer 3

the two hemispheres are connected by the corpus callosum. this allows information to be received from one hemisphere to be sent to the other hemisphere

Question 4

what is the corpus callosum

Answer 4

a bundle of nerve fibres that connect the two hemispheres of the brain. it allows the two sides of the brain to communicate with each other so that the whole brain can work as one complete organ.
In this way the two hemispheres retain their own roles while working together to control behaviour in the whole body

Question 5

what are split brain patients

Answer 5

a group of patients who had a corpus callosotomy - where the corpus callosum is severed so that the two hemispheres are separated and dont communicate with each other.
This is done to control frequent and severe epileptic fits.

Question 6

sperry’s split-brain research

Answer 6

11 split brain patients who had undergone hemisphere disconnection because they had a history of advanced epilepsy - comparison groups of ‘normal’ people.
An image or word presented to the Right visual field (processed by the Left hemisphere) and same or different image could be projected to the LVF (processed by RH)
Presenting the image to one hemisphere meant that the information could not be conveyed from that hemisphere to the other.

Question 7

Findings of Sperry’s research

Answer 7

Object shown to RVF:
- participant can describe what is seen (language centres in LH)

Object shown to LVF:
- cannot name object (no language centres with in RH)
- can select matching object behind screen using left hand
- can select object closely associated with picture (eg ashtray if a picture of a cigarette)