Lesson 8 Split Brain Research

Question 1

Sperry and Gazzaniga (1968) split brain research

Answer 1

Sperry and Gazzaniga (1968) investigated split-brain patients. Information from the left visual field goes into the right hemisphere, whereas information from the right visual field goes into the left hemisphere. Because in split-brain patients the corpus callosum has been severed there is no way for the information presented to one hemisphere to travel to the other.

Patients are asked to stare at a dot in the centre of a screen and then information is presented in either the left or right visual field. They are then asked to make responses with either their left hand (right hemisphere), right hand (left hemisphere) or verbally (left hemisphere) without being able to see what their hands were doing.

They may be flashed an image of a dog in their right visual field and then asked what they have seen. They will be able to answer ‘dog’ because the information will have gone into their left hemisphere where the language centres are. If a picture of a cat is shown in their left visual field and they are asked what they have seen they will not be able to say because the information has gone into their right hemisphere, which has no language centres. However, they can draw a picture of a cat with their left hand because the right hemisphere controls
this hand.

Question 2

Past split brain research

Answer 2

In the past surgeons have cut the corpus callosum in order to prevent the violent electrical activity caused by epileptic seizures crossing from one hemisphere to the other. Patients who underwent this form of surgery are often referred to as split-brain patients

Question 3

Advantages of split brain research

Answer 3

+ Experiments on split-brain patients are highly controlled and scientific.

Question 4

Disadvantages of split brain research

Answer 4

• The disconnection between the hemispheres was greater in some patients than others.
• Some split-brain patients have experienced drug therapy for much longer than others.
• The comparison groups were not considered to be valid as they were often people with no history of epileptic seizures.
• Many studies using split-brain patients have as few as three participants, making it hard for results to be generalised to the target population.
• The data from this research is very artificial. In the real world a severed corpus callosum can be compensated for by the unrestricted use of both visual fields. This means the research lacks ecological validity.