lateralisation & split brain research Flashcards
what is hemispheric lateralisation?
the idea that the 2 halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other
give an example of a function that isn’t lateralised
vision
how does vision work?
each eye receives light from the right visual field and left visual field. The LVF of both eyes is connected to the RH and the RVF of both eyes is connected to the LH. This enables the visual to compare the slightly different perspective from each eye and aids depth perception
what is a strength of lateralisation? (PET scans)
research has shown that even in connected brains the 2 hemispheres process information differently. PET scans have been used to identify that during a visual processing task, regions of the RH were much more active when looking at the pic as a whole but the LH was more active when looking at the detail. This increases the validity of the theory
what is a limitation of lateralisation? (Dominant side)
the idea that people have a more dominant side of the brain may be wrong. There may be different functions in the RH and LH but research suggests that people don’t have a dominant side of their brain which creates a different personality. This suggests that the notion of right or left brained people is wrong
what does a split brain operation involve?
severing the connections between the RH and LH (mainly the Corpus Collosum) which splits the brain in half
why are split brain procedures carried out?
to reduce the symptoms of epilepsy as during a seizure the brain experiences excessive electrical activity that travels between hemispheres
who’s research related to split brain studies? what did he devise?
sperry (1968) devised a system to study how 2 separated hemispheres deal with things like speech and vision
explain sperrys split brain study?
11 people who had a split brain surgery were studied using a set up in which an image could be projected to a ppts RVF (processed by LH) and the same or different image could be projected to the LVF. In. connected brain, the cc would immediately share info between hemispheres to have a complete picture. However presenting the image to 1 hemisphere of a SB ppt meant the info can’t be conveyed between hemispheres
explain the findings of sperrys research
when a pic was shown to a ptts RVF (LH) the ppt could describe what they could see but they couldn’t do this when it was presented to the LVF (RH). this is because in a connected brain messages from the RH are relayed to the LH language centres but this isn’t possible in the split brain patients. Instead, they could select a matching object to what they saw using their left hand
what is a strength of split brain research? (Support)
there’s support from more recent research. A study done showed that split brain patients actually perform better than connected brains. for example, they could find an odd one out easier than normal patients. This supports sperrys findings than the left brain and right brain are distinct
what is a limitation of split brain research? (Comparing)
One limitation is that the behaviour of the split brain patients were compared to a neurotypical control group without epilepsy. This is a major confounding variable as it means that any differences observed may be a result of epilepsy and not a split brain. This means that some of the unique abilities may have been due to epilepsy not the procedure. Also, not many people have had a split brain surgery so findings will be hard to generalise.
