Split brain [HEMISPHERIC LATERALISATION] Flashcards
What is the idea of hemispheric lateralisation?
Specific behaviours and functions exist only in one hemisphere
How has hemispheric lateralisation been demonstrated in research?
Sperry’s split brain patients
What is split brain?
When the corpus callosum has been split (normally for epilepsy treatment), cutting off transmission between the hemispheres
What were the 4 investigations Sperry employed to investigate split brain patients?
Describe what you see
Recognition by touch
Composite words
Matching faces
What was the procedure of ‘describe what you see’?
Ppts focused on a centre cross on a screen whilst a word appeared on either side - this was done quickly to avoid both visual fields from seeing it. The words on the right visual field were easily described, however the ones on the left weren’t even reported as being seen. When given 4 pictures, the picture of the ‘unseen’ word was picked
= IT WAS PROCESSED
How does ‘describe what you see’ support the idea of hemispheric lateralisation?
The language centre is in the left hemisphere, as only the right visual field could process the language
How did ‘recognition by touch’ support the theory of hemispheric lateralisation?
[same procedure as describe what you see] the ppt was asked to feel unseen objects, and they would always choose the one most associated with the ‘unseen’ word
= INFO IS PROCESSED BUT WITHOUT THE CORPUS CALLOSUM TRANSMITTING INFO HEMISPHERICALLY , THEY CANNOT ACCESS THE LANGUAGE CENTRE FOR VERBAL DESCRIPTION
How does the case study of Kim Peek support research into split brains?
Born without a corpus callosum, he displays almost no lateralisation between hemispheres - both visual fields are able to read different pages simultaneously as the information is not transmitted across
Why is Kim Peek not the best case study to rely on?
Plasticity caused the development of language centres in both hemispheres, so arguably lateralisation is not actually being tested
What are the pros and cons of the theory?
PRO: the debate led to more research, which can subsequently help in perfecting brain surgeries which may involve lesioning
CON: it has been misinterpreted in popular psychology which could result in misapplication on patients
Why is there issues with generalisation?
There was only 11 patients
The control group didn’t have epilepsy, which could’ve altered the brains of the ppts before split brain
The extent of severing could differ between ppts - some could retain some function
