Lesson 7 - Lateralisation Of Function Flashcards
What is meant by Lateralisation of Function?
This is the idea that the two hemispheres of the brain have different specialisations.
What is the Right hemisphere responsible for? (2)
The right hemisphere is responsible for the left hand side of the body.
The right hemisphere is dominant for recognising faces.
What is the Left hemisphere responsible for? (2)
The left hemisphere is responsible for the right hand side of the body.
The left hemisphere is dominant for language (Broca’s and Wernicke’s Areas).
What are the two hemispheres connected by?
The two hemispheres are connected by a bundle of nerve fibres known as the corpus callosum.
What is an advantage of Lateralisation of Function?
An advantage of Lateralisation of Function is that it increases neural processing capacity which is adaptive. For example, when one hemisphere is engaged in a particular activity, the other hemisphere is free to engage in another one (two functions can be carried out at once according to the lateralisation of function theory). Rogers (2004) supports this claim where he discovered that chickens can carry out two tasks simultaneously (finding food and being vigilant to predators) thanks to the lateralisation off function).
What is a disadvantage of Lateralisation of Function?
There are individual differences in Lateralisation of Function - JW developed the capacity to speak using his right hemisphere as well as in his left hemisphere (it was believed that the left hemisphere was dominant for language).
Who are split-brain patients?
Split-brain patients have their corpus callosum cut to prevent the electrical activity caused by epileptic seizures from crossing from one hemisphere to the other.
Who investigated split-brain patients?
Sperry and Gazzaniga (1968)
Where does information from the left visual field go?
The right hemisphere
How was split-brain research carried out?
Patients were asked to stare at a dot in the centre of a screen. Information such as words and animals were then presented to either the right visual field or the left visual field. The patients are then asked to respond to what they have seen with either their left hand (right hemisphere), right hand (left hemisphere) or verbally (left hemisphere) (which is dominant for language / where language centres are).
What was the results of the split-brain research?
When a picture of a ‘dog’ was presented in the split-brain patients right visual field, they could verbally respond with ‘dog’ as the information would go to the left hemisphere which is where language centres are located, However, when a picture of ‘cat’ was presented in the split-brain patients left visual field, they could NOT verbally respond with what they saw because the information would go to the right hemisphere which has no language centres. However, patients could draw the picture of the cat with their left hand as the right hemisphere controls that hand.
What are three weaknesses of split-brain research?
- Many studies on split-brain patients have very small samples and therefore it is very hard to generalise results.
- In the real world, a severed corpus callosum in split-brain patients can be compensated for by the unrestricted use of both visual fields (can still see everything but just has to turn head more for particular functions) - lacks ecological validity.
- The disconnection between hemispheres is greater in some split-brain patients compared to others. This is due to some patients having previously used drug therapy to treat their epilepsy for longer than others which ultimately affects how their brain works. Therefore, the findings of split-brain research cannot be generalised to the target population.
