Biopsychology: Hemispheric lateralisation and split-brain research Flashcards
(16 cards)
What is the brain split into?
The left and right hemispheres
What are the two hemispheres connected by and what does it do?
The corpus callosum - acts as a bridge between the two hemispheres and allows them to send messages and work together
Where are the 2 main centres for language located?
Left hemisphere:
Broca’s area= left frontal lobe
Wernicke’s area= left temporal lobe
- so language is lateralised (performed by one hemisphere)
The LH controls movement on what side of the body?
Right side of the body
Is vision lateralised?
No
How does vision work?
- Each eye receives light from LVF and RVF
- LVF of both eyes= connected to RH
- RVF of both eyes= connected to LH
- This enables the visual areas to compare the slightly different perspective from each eye and aids depth perception
What does a split brain operation involve?
Severing the connections between RH and LH, mainly the corpus callosum
What is this surgical procedure commonly used for?
Reducing epilepsy
Who did research into split brain?
Sperry
What was the AIM of Sperry’s research?
AIM:
- To see how the two hemispheres deal with, in this case, speech and vision
What was the PROCEDURE in Sperry’s research?
PROCEDURE:
- 11 people who had split-brain operations were studied
- meant that info could not be communicated between the 2 hemispheres
- An image was projected to RVF (processed by LH) & same/different image projected to LVF (processed by RH)
What was the RESULTS of Sperry’s research?
RESULTS:
Picture of object shown to RVF= participant would describe what was seen
Picture of object shown to LVF= participant said nothing was there but could select matching objects out of sight using left hand (linked to RH)
What was the CONCLUSION of Sperry’s research?
CONCLUSION:
- show how certain functions are lateralised in the brain
- support view that LH is verbal and RH is ‘silent’ but emotional
EVALUATION: Split brain research
(one strength/ one limitation)
Strength: Research support
- has been supported by more recent split-brain research
- e.g. Luck et al showed split-brain participants actually performed better than connected controls on certain tasks
- they were faster at identifying the odd one out in an array of similar objects than normal controls
- In the normal brain, the LH better cognitive strategies are ‘watered down’ by the inferior RH
- supports sperry’s earlier findings that the ‘left brain’ and ‘right brain’ are distinct
Limitation:
- Small sample was used
- hard to generalise these findings to wider population (their brains may be abnormal in other ways)
- comparison group used by Sperry were not people with a history of epileptic fits (so not a valid comparison)
EVALUATION: Hemispheric lateralisation
Strength - lateralisation in the connected brain
P: research shows that even in connected brains the two hemispheres process information differently
E: Fink et al
- used PET scans to identify which brain areas were active during a visual process task
- when p’s with connected brains were asked to look at whole elements of a picture (e.g. picture of a whole forest)= regions of RH much more active
- when asked to look at finer details, like individual trees= the specific areas of the LH tended to dominate
L: suggests hemispheric lateralisation, in this case with visual processing, is a feature of the connected brain as well as the split-brain
EVALUATION: Hemispheric lateralisation
Limitation - One brain
P: Idea that LH= analyser RH= synthesiser may be wrong
E: may be different functions in the RH & LH
- researchers suggests people do not have a dominant side of their brain which created a different personality
- research that analysed brain scans of over 1000 people aged 7-29 years= found that people used certain hemispheres for certain tasks (evidence for lateralisation)
E:
- no evidence of a dominant side
- e.g. artists brain or mathematician’s brain
L: suggests that the notion of right or left brained people is wrong
