Hemispheric lateralisation Flashcards
What is hemispheric lateralosation
The idea that the two hemispheres of the brain are functionally different and certain processes are mini controlled by one rather than the other
what is the corpus Callosom
bundle of nerve fibres which connect the two hemispheres
Allows the two hemispheres to communicate by sending information to and receiving from each other
what was the method of Sperry and Gazzanigas split brain research?
- 11 split brain patient who had surgery for epilepsy
- In lab conditions they were asked to fixate on a dot on the centre of the screen while a word/image was presented to the left or right visual field for a split second
- they would then be asked to make responses with their left/right hand, verbally or without being able to see what their hands were doing
how did patients react when they were shown an object in the RVF compared to the LVF?
when a picture was shown to the RVF as they could easily describe it
however if the same thing was shown in the LVF, they reported that nothing was there
However, they were able to slap their matching object from a bag using their left hands and will also able to draw the object
What would split brain participants do if two words were simultaneously represented on either side of the visual field and why?
Write the word on the left with the left hand and say the word on the right
this is because the left side of the brain is responsible for language which affects the RVF, as there’s no language on the right side of the brain and the cc has been severed information cannot pass to reach the LVF
How did split brain participants act when they had to do facial recognition
when asked to match a face from a series of other faces the picture processed by the right was consistently selected and the picture presented to the left was ignored
What are strengths of sperrys research?
high control- quasi
increased our understanding
evaluate high control as a strength of sperrys research
- it is a quasi-experiment as they were able to take advantage of a naturally occurring variable as the epileptic patients had suffered hemisphere disconnection
- they were able to have high control over the experimental environment and demonstrate the effect the hemisphere had brain function
- as hemisphere connection was the only significant difference between the two groups the observed difference in performance was seen to have been caused by this disconnection, thus providing support to the series of hemispheric lateralisation
- High internal validity
Evaluate pioneering research as a strength of Sperrys study?
- strength is that research has a huge impact on out understanding of how the hemispheres work
- Sperry’s study produces a large amount of research that suggests the left hemisphere is geared towards verbal tasks and the right is used for more spatial tasks
- strength as the research enables scientific progress
What is a strengths of Hemispheric lateralisation
supported by tan
What are limitations of Hemispheric lateralisation
contradictory evidence
individual differences
oversimplistic
Evaluate contradictory evidence about language as a limitation of hemispheric lateralisation
- language may not be restricted to the left hemisphere in all people
- e.g right handed people generally develop language in the left whereas left handed people may have them on either side
- limitation as it may be wrong to assume that lateralisation of language centres is universal
Evaluate individual differences as a limitation of Hemispheric lateralisation
- it changes with age and types of task
- lateralisation patterns found in youngers switch to bilateral patterns in healthy adults. e.g A study found that language became more lateralised to the left hemisphere with increasing age in children but after the age 25 lateralisation decreased. Suggests older people’s brains need both hemispheres possibly to compensate for age-related cognitive decline
- limitation as findings suggest theory may not be completely correct
Evaluate oversimplicity as a limitation of hemispheric lateralisation
- oversimplifies the functional distinction between left and right hemispheres
- although verbal and non verbal labels can be used to summarise the differences between the 2 hemispheres, modern neuroscientists argue the actual distinction is less simple
- in the normal brain the two hemispheres are in constant communication when performing everyday tasks. Some behaviours associated with one hemisphere can be performed by the other in some occasions (plasticity)
