split-brain research Flashcards
what is split-brain research?
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
outline the procedure of Sperry’s research
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
outline what Sperry found
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
what did Sperry conclude?
certain functions lateralised in the brain
study supports view that LH verbal and RH ‘silent’ but emotional
strength- research support
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
limitation- causal relationships hard to establish
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
ethics
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