Lateralisation - Split Brain Research

Question 1

What are split brain patients?

Answer 1

are those who have had the connection between the left and right hemispheres severed. (The corpus callosum has been cut)

Question 2

What differs from split brain patients to non-split brain patients?

Answer 2

in split brain P’s the two hemipsheres do not share information like normal brains do

Question 3

What processes are involved in split brain research?

Answer 3

• uses a split visual field and visual stimuli are presented to either the right or left visual field, or both at the same time.
• P’s are asked to fixate on a central point and stimuli are presented really quickly (to ensure P does not move their head or eyes.
• the stimuli presented to the LVF is processed by the right hemisphere and vice versa
• researchers can learn about what the left and right hemisphere process depending on how P’s can respond.

Question 4

What was found when words projected to the LVF? what does this suggest?

Answer 4

the words did not seem to be registered. P’s would say they had not seen anything

suggests that the LH is responsible for language (so words need to be presented to RVF to be registered)

Question 5

What was found when a word projected to the LVF is under a screen with a variety of objects? what does this suggest?

Answer 5

P’s couldn’t verbally identify what they had seen but they would select the corresponding object with left hand

Question 6

What was found when different face pictures was presented to LVF and RVF’s and P’s given a set of face pictures and asked to select faces they had been shown? what does this suggest?

Answer 6

P’s chose the face presented to the LVF

shows the right hemisphere is dominate when tasks involve shapes and faces (i.e. visospatial tasks)

Question 7

What are the strengths of split brain research (application)?

Answer 7

• useful practical applications
• enables a greater understanding of the differing functions of the hemisphere and adding to the unity of the consciousness debate
• for instance, we now know that language is largely processed in the left hemisphere

Question 8

What are the strengths of split brain research (methodology)?

Answer 8

• Good standardized procedures
• Sperry carefully standardized procedures which gives findings high internal validity (image flash up for 0.1 secs)
• allowed Sperry to vary aspects of the basic procedure and ensure only one hemisphere received information at a time - very useful and well controlled procedure

Question 9

What are the weaknesses of split brain research (mundane realism)?

Answer 9

Whilst P’s were clearly dealing with the real life problem of having their corpus callosum severed, it could be argued that the experimental set-up lacked mundane realism as in real life, the severed corpus callosum can be compensated for by the unrestricted use of two eyes

this means that the findings may not tell us much about hemispheric functioning and coping with a split brain in real life day to day situations

Question 10

What are the weaknesses of split brain research? (cofounding variables)

Answer 10

• Split brain P’s were often compared to neurotypical controls, but these people often had no history of epilepsy (i.e. not matched pairs)
• therefore this could be a potential confounding variable as a history of epilepsy would effect general behavior
• this means it is harder to establish cause and effect and there could be other explanations for split brain findings, such as damage to brain function caused by severe epilepsy