split-brain research and hemispheric lateralisation Flashcards
What is hemispheric lateralisation?
the idea that the two halves of the brain are functioning differently and each hemisphere has functional specialisations, e.g. the left is dominant for language, and the right is dominant for visual motor tasks.
The two are connected through nerve fibres called the corpus callosum.
What are the nerve fibres that connect the two hemispheres called?
the corpus callosum.
What is the function of the corpus callosum?
facilitate interhemispheric communication (allow the left and right hemisphere to ‘talk’ to each other).
Who conducted the first study into hemispheric laterilisation?
Sperry and Gazzinga (1967).
What is a split-brain patient?
individuals who have undergone a surgical procedure where the corpus callosum, which connects the two hemispheres, has been cut.
this procedure, which separates the two hemispheres, was used as a treatment for epilepsy.
what was the aim of the research by Sperry and Gazzinga (1967).
to examine the extent to which the two hemispheres are specialised for certain functions.
Describe the procedure of the research by Sperry and Gazzinga (1967).
An image/word is projected to the patients left visual field (processed in right hemisphere) or the right visual field (processed in left hemisphere).
When info is presented to one hemisphere in a split-brain patient, the info is not transferred to the other hemisphere (because the corpus callosum is cut).
Conducted describe what you see, tactile and drawing tasks.
describe what you see - a picture was presented to either the left or right visual field and the ptp had to describe what they saw.
tactile - an object was placed in the patients left or right hand and they had to either describe what they felt, or select a similar object from a series of other objects.
drawing - ptps were presented with a picture in either their left or right visual field, and they had to draw what they saw.
Outline the results of the describe what you see task in the research by Sperry and Gazzinga (1967).
right VF - the patient could describe what they saw, demonstrating the dominance of the left hemisphere when it comes to language production.
left VF - patient could not describe what was shown and often reported that there was nothing present.
Outline the results of the drawing task in the research by Sperry and Gazzinga (1967).
right VF - while the right hand would attempt to draw a picture, the picture was never as clear as the left hand.
left VF - the left hand would consistently draw clearer and better pictures than the right-hand (even though all ptps were right-handed). This demonstrates the superiority of the right hemisphere when it comes to visual motor tasks.
Outline the results of the tactile task in the research by Sperry and Gazzinga (1967).
right hand - patient could describe verbally what they felt. right hand could also identify the test object presented to them in the right hand by selecting a similar appropriate object from a series of alternate objects.
left hand - patient could not describe what they felt and could only make wild guesses. However, the left hand could identify a test object presented in the left hand by selecting a similar appropriate object from a series of alternate objects.
Outline the conclusions drawn from the research by Sperry and Gazzinga (1967).
the research highlights a number of key differences between the two hemispheres.
the left hemisphere is dominant in terms of speech and language.
the right hemisphere is dominant in terms of visual-motor tasks.
what is the main advantage of brain lateralisation?
it increases neural processing capacity (the ability to perform multiple tasks at once).
Who conducted the research to find that hemispheric lateralisation is associated with the ability to perform multiple tasks at once?
Rogers et al (2004)
Discuss the research of Rogers et al (2004) as a strength of hemispheric lateralisation.
found that in domestic chickens hemispheric lateralisation is associated with an enhanced ability to perform two tasks simultaneously (finding food and being vigilant for predators).
Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions.
This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks.
Discuss the research by Turk et al (2002) as a counterargument to hemispheric lateralisation being fixed.
It could be argued that language is not restricted to the left hemisphere.
Turk et al (2002) discovered a patient who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere eventually leading to the ability to speak about the info presented to either side of the brain.
Suggests that perhaps lateralisation is not fixed and that the brain can adapt following damage to certain areas.
