split-brain research

Question 1

what is split-brain research?

Answer 1

studies involving people with epilepsy who experienced a surgical separation of the hemispheres of their brain (severed corpus callosum) to reduce severity of epilepsy
stops LH and RH connecting with each other
enables researchers to test lateral functions of brain in isolation

Question 2

outline the procedure of Sperry’s research

Answer 2

1968- devised system to study how two separated hemispheres deal with speech and vision

11 people with split-brain operation
image projected to RVF (processed by LH), and same or diff image projected to LVF (processed by RH)

‘normal’ brain- corpus callosum share info between hemispheres giving complete picture
split-brain communication cannot occur

Question 3

outline what Sperry found

Answer 3

picture of object shown to RVF (LH)- could describe
couldn’t if shown to LVF (RH)- ‘nothing there’
because RH cannot relay info to language centres in LH

but LVF could select matching object out of sight using left hand (RH)
also able to select closely associated objects (e.g. cigarettes and ashtrays)

pin-up photo shown to LVF- emotional reaction (e.g. giggle), but reported seeing nothing
RH emotional context but cannot describe

Question 4

what did Sperry conclude?

Answer 4

certain functions lateralised in the brain

study supports view that LH verbal and RH ‘silent’ but emotional

Question 5

strength- research support

Answer 5

Gazzaniga- split-brains perform better than connected on certain tasks
e.g. faster at identifying odd one out in array of similar objects
bc connected LH cog strategies ‘watered down’ by inferior RH

strength- supports LH and RH distinct, high ext validity

Question 6

limitation- causal relationships hard to establish

Answer 6

Sperry’s split-brains compared to neurotypical control group
no controls had epilepsy- confouning variable

any differences observed may be due to epilepsy not split brain

limitation- low int validity, can question findings

Question 7

ethics

Answer 7

split-brain operation not performed for research purposes
not deliberately harmed
fully informed consent obtained
strength- ethically valid

may not have fully understood implications of what agreed to due to op trauma
subject to repeated testing over lengthy period- may have been stressful
issue- ethical issues

didn’t intend harm but may have been neg consequences resulting from involvement
difficult to say that studies were ethical, even though Sperry probably observed ethical guidelines