Lateralisation and Split-Brain research Flashcards
What is the aim of split brain research
To investigate the effects of brain lateralistion
What is brain lateralisation
Brain lateralization refers to the fact that the two halves of the human brain are not exactly alike, with each hemisphere having functional specializations, for example, research has found that the left hemisphere is dominant for language and speech, whereas the right excels at visual-motor tasks
Give an example of a brain area not mirrored
Broca’s area is not mirrored in the right hemisphere
What connects the two brain hemispheres
The corpus callosum, a bundle of nerve fibres
What gave researchers the opportunity to investigate the different abilities of the two hemispheres
As a treatment for severe epilspsy, surgeons cut the corpus callosum, stopping communication between the two hemispheres and creating split brain patients
Who are the leading researchers in the field of split brain research
Sperry and Gazzaniga
What was a typical study for Sperry and Gazzaniga
The split brain patient would fixate on a dot in the centre of the scree while information was presented to either the left or right visual field. They were then asled to make responses with either their right hand (left hemisphere), left hand (right hemisphere) or verbally (left hemisphere)
What would happen if a split brain patient was flashed an image of a dog in their right visual field
They would verbally respond that they had seen a dog
What would happen if a split brain patient was flashed an image of a dog in their left visual field
They would respond that they see nothing, as information in the left visual field is processed by the right hemisphere which has no language centre
What differences in the brain hemispheres has split brain research revealed
The left hemisphere is responsible for speech and language, while the right hemisphere specialises in visual-spatial processing and facial recognition
What is an important point about conclusions drawn from split brain research
It hasn’t shown that the brain is localised, instead it has shown that connectivity between the different regions is as imporant as the operation of the different parts
What appears to be the strength of hemispheric lateralisation (eval)
It increases neural processing capacity, as by using only one hemisphere to engage in a task, this would leave the other hemisphere free to engage in another function
What research supports the view that hemispheric lateralisation increases neural processing capacity
Rogers et al chemically severed the corpus callosum of chickens and found that in the domestic chicken, brain lateralisation is associated with enhanced ability to perform two tasks simultaneously, looking for food and being vigilant for predators. Suggests lateralisation improves brain efficiency
Who chemically severed chicken’s brains
Rogers
How are individual differences present in research into brain lateralisation (eval)
Lateralisation doesn’t appear to stay the same throughout an individual’s lifetime, with lateralised patterns found in youger people swithing to bilateral patterns in older adults. Szaflarski et al found that lagnuge became more lateralised to the left hemisphere with increasing age in children and adolescents, but after the age of 25 lateralisation decreases with each decade of life. One reason could be that using the extra processing power of the other hemisphere may in some way compensate declines in function
What did Szaflarski do
Szaflarski et al found that lagnuge became more lateralised to the left hemisphere with increasing age in children and adolescents, but after the age of 25 lateralisation decreases with each decade of life
Who found increasing lateralisation until the age of 25
Szaflarski et al
Why is particiapant number an issue for research into lateralisation (eval)
The split brain procedure is rarely carried out today, and Andrewes points out that many studies are presented with as few as three participants or even a single participant.
What does Anderson claim about split-brain research
He claims that in some cases conclusions have been drawn from individuals who either have a confounding physical disorder which made the procedure necessary, or have had less complete sectioning of the two hemispheres then was originally believed. Confounding factors and insufficient research numbers are therefore a huge issue
Who found split brain research studies have been done on as few as 1 participant
Andrewes
Why might early split brain research discoveries have been disconfirmed
Gazzaniga suggesed more recent discoveries have disconfirmed early discoveries. Turk et al conducted a case study of one patient, known as J.W., which demonstrated that he had developed the capacity to speak out of the right Hemisphere, with the result that he could speak about information presented to the left or the right brain. This challenges the claim that the right hemisphere is unable to handle even the most rudimentary language
Who claimed that new discoveries were disconfirming earlier lateralisation research
Gazzaniga
Who found a case study who could speak out of their right hemisphere
Turk et al
Who was the case study discovered by Turk
J.W
