biopsychology - lateralisation and split-brain research Flashcards
what is hemispheric lateralisation?
behaviour is controlled by either the left or right hemisphere
e.g research suggests language is lateralised to the left
how is the motor area contralateral?
LH controls the right side of the body and the RH controls the left
how is vision contralateral and ipsilateral?
each eye receives light from RVF and LVF
LVF of both eyes connected to RH and RVF to LH
enables the visual areas to compare the slightly different perspectives from each eye and aids depth perception
what are contralateral brain connections?
the control of behaviour is on the opposite side of the brain
(e.g LH controls right side of body)
strength of hemispheric lateralisation - research support
PET scans during visual processing task showed global elements processed by RH while finer detail was processed by LH (Fink et al, 1996)
limitation of hemispheric lateralisation - no dominant hemisphere
analysis of brain scans from over 1000 people found certain hemispheres used for certain tasks but no dominant side (Nilsen et al (2013)
challenges common notion of right-brained and left-brained people and the impact of dominant side on personality
who conducted split-brain research?
Roger and Sperry (1968)
what is the split-brain operation?
treatment for epilepsy in which the corpus callous is cut through
reduces uncontrolled electrical brain activity that leads to fits
stops hemispheres from communicating
split-brain research - procedure
11 split-brain patients studied
set-up in which an image would be flashed to either RVF and processed by LH or to LVF and processed by RH
‘normal’ brains - information would be shared across corpus callous between hemispheres, but this doesn’t occur in split-brain patient
split-brain research - findings
when a picture was processed by the LH, the participant could describe what they’d seen, but unable to when processed by RH - said they saw nothing
couldn’t label objects shown to LVF, but could select matching object with their left hand
if a pinup picture was shown to LVF there was an emotional reaction but the participants reported seeing nothing
split-brain research - conclusions
certain functions are lateralised in the brain (e.g language lateralised to the left, motor area is contralateral)
strength of split-brain research - research support
split-brain patients faster at tome tasks (Luck et al, 1989) as LH’s better cognitive strategies aren’t slowed down by inferior RH (Kingstone et al, 1995)
limitation of split-brain research - generalisation
epilepsy is a confounding variable as split-brain patients were compared to neurotypical control group who didn’t have epilepsy
findings could be the result of epilepsy rather than split-brain procedure
