Split Brain Research

Question 1

What is the background of split brain research ?

Answer 1

• 1950’s
• in cases of severe epilepsy one solution for those who hadn’t been helped by meds was to have surgery to disconnect the two hemispheres
• this restricted the seizure to one half of the brain, reducing the severity
• had mixed results

Question 2

In a split brain procedure what is cut?

What is the procedure known as?

Answer 2

• Corpus Callosum (commisural fibres)

- Commissurotomy

Question 3

What processes are involved in split brain research?

Answer 3

• split brain research uses a divided visual field
• p’s are sat in front of the screen and asked to look at a fixed point at the centre of the screen
• visual stimuli are projected onto the screen either to the right or left visual field at a very high speed so the p has no chance to move their head and is only able to process the image in the visual field where it was placed

Question 4

1-
What was done? Words were projected to the LVF (RH)

What was this testing?
Findings?
What this suggests

Answer 4

• verbal responses to language
• the words did not seem to register, p’s would say they had not seen anything
• suggests that the LH is responsible for language (so words need to be presented to the RVF to be registered)

Question 5

2-
What was done? A word (e.g. fork) was projected to the LVF (RH)

What was this testing?
Findings?
What this suggests

Answer 5

• physical responses to language
• L hand (RH) was placed behind a screen with objects. P’s could select the right object despite being unable to verbally report it
• This indicates that the RH does have some language ability for understanding words if not for speech

Question 6

3-
What was done? A different face presented to each hemisphere at the same time, p’s then given set of faces and asked to identify those they had seen

What was this testing?
Findings?
What this suggests

Answer 6

• Matching abilities in response to pictures
• p’s chose the one presented to the RH/LVF indicating its role in identifying faces and shapes
• this indicated that the RH is responsible for visual spatial tasks

Question 7

Summarise evaluations of Split brain research

Answer 7

• useful practical applications - greater understanding of the differing functions of the hemispheres + adding to unity of consciousness debate - allows our scientific understanding to move on
• lacks generalisability- limited number of p’s (10-15) + they varied considerably in age gender etc - lacks representativeness making it inconclusive
• only compared to neurotypical controls (no history of epilepsy) - confounding variable - difficult to establish cause and effect
• Sperry’s procedure strength - mixture of quasi + case studies -> able to combine qualitative and quantitative- combination of methods allows the collection of statistically reliable info to be enhanced