Biopsychology split brain research Flashcards
what is hemispheric lateralisation ?
The idea that two hemispheres of the brain are functionally different and certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.
- example is speech production is localised(brocas areas) and lateralised ( left hemisphere)
what is the corpus collosum?
-The corpus collosum connects the two hemispheres through bundles of nerve fibres.
- Allows the hemisphere to communicate by sending information to and from each other.
-its needed so we can talk about things experienced on our left hemisphere such as facial recognition. Language is in the left hemisphere but facial recognition is in the right hemisphere.
why did surgeons cut the corpus callosum?
- As a treatment for epilepsy.
- to prevent violent epileptic seizures crossing from one hemisphere to another.
- known as split brain patients.
discuss the difference between how information is processed differently in a normal brain to a split brain and why this is?
- a series of studies that involve epileptic patients who experienced the surgical separation of the two hemispheres, allowed researchers to investigate which brain function is lateralised.
- the intact human visual system is organised so if an object is present in a right visual field it is processed by the left hemisphere and if an object is present in the left visual field it is processed by the right hemisphere.
- in normal human brains the information processed in each hemisphere is immediately shared to one another due to the corpus callosum, giving a complete picture of the visual world.
- however in a split brain patient this is not possible. If a split brain patient focuses straight ahead anything present in the rvf would be only processed by the left hemisphere and not to the right hemisphere at all.
what was the aim of SPERRY & GAZZANIGAS study used to investigate hemispheric laterization ?
AIM- to investigate the effect of hemisphere disconnection and to show each hemisphere has different functions.
what did SPERRY & GAZZANIGA do in their key study on hemisphere disconnection?
method-
-11 split brain patience, who underwent surgery due to epilepsy were compared to people with no hemisphere disconnection or no epilepsy.
- Lab condition, ptsp asked to fixate on dot in centre of screen whilst word or image was presented on either LVF or RVF for less than 1/10 of a second.
- asked to make responses with left hand (controlled by right hemisphere) ,right hand( controlled by left hemisphere) or verbally ( controlled by left hemisphere) without being able to see what hands were doing.
What were the results of SPERRY & GAZZANIAGS key study on split brain patience?
RESULTS-
1. when picture of object was presented on patience RVF patient could verbally describe what they saw. If same object was shown on their LVF the patience reported there was nothing there, but could draw the picture with left hand.
2. 2 words presented on screen at same time on either visual field. Patient would verbally say the word presented in the RVS but draw the word presented in the left visual field with left hand.
3. when patience were presented with pictures of faces on the right visual field and left visual field they would always correctly match the left visual field. Meaning face recognition is located in right hemisphere only.
What is the conclusion of Sperry & Gazzaniga’s key study on split brain patience.
-different hemispheres of the brain are responsible for different tasks
- face recognition is lateralized in the right hemisphere
- language is lateralised to the left hemisphere
explain the evaluation point of Sperry and Gazzaniga’s study having pioneering research ?
p- a strength of this research is it had a huge impact on our understanding of the different hemispheres.
e- their work into the split brain phenomenon produced impressive and large amount of evidence, suggesting the left hemisphere is responsible for speech and language and the right is responsible for face recognition and spatial tasks.
e- this is a strength as its allowed scientific progress in this area.
what is the evaluation point for population validity on Sperry and Gazzaniga’s study of split brain research?
p- limitation is it has low population validity.
e- the sample size is 11 split brain patience which is a small sample size, which may not be representative to the larger population size. Aswell as this, all the patience had a history of epilepsy which may have caused changes in their brain- unrepresentative to population who don’t have history of epilepsy.
e- therefore lacks external validity.
What is The evaluation point on Sperry and Gazzaniga’s study on split brain patience about it being a quazi experiment ?
p- this study was conducted in a lab with high control over extraneous variables and the environment and stimuli. The Iv was a naturally occurring variable that the patience had previously had surgery to separate their hemispheres. The only difference in variables was the split brain in the patience therefore dv has to be due to that. Therefore findings have high internal validity and strongly supports the theory that the brain is lateralised.
what are two overall evaluation points of hemispheric lateralisation?
- the theory of hemispheric laterization is supported by the case study of tan.
- a limitation is that there is contradictory evidence about language. Left handed people may develop language in both hemispheres.
