Split-brain Research Flashcards
What is split-brain research?
Research investigating hemispheric lateralisation by conducting on split-brain patients who have…
had surgery to remove the corpus callosum (which connects the 2 hemispheres).
Outline hemispheric lateralisation and Sperry’s split-brain research (AO1)
> Hemispheric lateralisation is the idea that the two halves of the brain are functionally different, and that each hemisphere has functional specialisations.
> The aim of Sperry’s split-brain research (1968) was to investigate hemispheric lateralisation.
> The participants were 11 split-brain patients who had their corpus callosum severed through a surgery known as commissurotomy.
> Sperry’s methodology included 4 variations.
> One variation was known as the “Describe what you see” task in which an image was presented to either the left or right visual field and the participant had to simply describe what they saw.
> Patients were blindfolded to focus on one visual field.
> Another variation is the “Recognition by touch” task where an object was place in the patient’s left or right hand and they had to describe what they felt.
What is meant by hemispheric lateralisation?
When 2 halves of the brain are functionally different, and each hemisphere has functional specialisations.
The idea that each of the two hemispheres of the brain perform different functions.
E.G.
The left is dominant for language, and the right excels at visual motor tasks.
Language is hemispherically lateralised to the left hemisphere, and spatial skills are hemispherically lateralised to the right hemisphere.
What is the name of the nerve fibres that connect the 2 brain hemispheres, and what does it do?
Corpus callosum
Facilitates the interhemispheric communication - allowing left & right hemispheres to ‘talk’ to one another.
What is the name of the surgery that removes the corpus callosum?
Commissurotomy
How many patients did Sperry use for his split-brain sample?
11
How did Sperry ensure patients would focus on one visual field at a time?
He blindfolded them.
What are split-brain patients?
Patients who have had surgery (commissurotomy) to cut the corpus callosum to separate the 2 hemispheres.
It is a treatment for severe epilepsy.
What is the corpus callosum?
A bundle of axons connecting the 2 hemispheres in order for them to communicate through nerve impulses.
What is the process used in split-brain research in simple terms?
1 = A stimulus is presented to either the patient’s left or right hemisphere.
2 = Patients are asked to respond to a stimulus that has been presented to them.
What does it mean if a function is hemispherically lateralised to the left hemisphere?
Then the patient will only be able to perform the function if the stimulus is presented to the left hemisphere.
Only processes right-hand side of the body.
What does it mean if a function is hemispherically lateralised to the right hemisphere?
Then the patient will only be able to perform the function if the stimulus is presented to the right hemisphere.
Only processes left-hand side of the body.
What if a function is not hemispherically lateralised?
Then the patient should be able to perform the function, regardless of whether the stimulus is presented to the right or left hemisphere.
Give examples of things that are organised contralaterally and not organised contralaterally but are processed by both hemispheres.
Organised contralaterally =
vision, movement, touch
Processed by both hemispheres but not organised contralaterally =
hearing, smelling, taste
What does it mean if a sense e.g. vision, movement and touch is organised contralaterally?
When the right hemisphere controls the left side of the body, and the left hemisphere controls the right side of the body.
