Biopsychology-Sperry's split brain research

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  • Created by: Anca.a
  • Created on: 07-04-18 14:41
What is epilepsy?
a medical condition characterised by uncontrolled electrical discharges in the brain.If these are severe then brain function may be seriously affected & person may suffer violent convulsions and lose consciousness.
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What are the two hemispheres of the brain connected by?
The corpus callosum, a bundle of 200-300 million fibres.It allows epileptic discharges to travel from one hemisphere to the other, meaning epilepsy can involve the whole brain.
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What did they do in the 1940's to reduce the severity of the attack?
a commissurotomy - operation to cut the corpus callosum.BUT, this operation was not successful at reducing the symptoms but the patient did not suffer any ill effects either, considering they lost one of the major pathways in the brain.
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What type of researcher was Sperry?
An opportunist because he did not sever the corpus callosum of the patients himself, the participants had to have brain surgery because medication wasn't working for their seizures.This means the study was a natural experiment.
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Sperry aim:
to study the effect of hemisphere disconnection and to show that each hemisphere has different functions
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Sperry patients:
11 "split-brain" patients with a history of epilepsy
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Sperry procedure: Visual tests
p's sat in front of a projector screen and focused on the fixation point in the middle.Visual stimuli(image/word)would appear for 1/10th of 1 second on the screen.Stimuli was presented to 1 or both visual fields.
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Presenting stimuli to 1 visual field only:2 separate memories?
If a stimulus was shown to one visual field, it was only recognised again if it was presented to the same visual field
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Presenting stimuli to 1 visual field only:matching pictures
if an image was presented to their LVF, the participant could point to a matching picture or object with their left hand; though they insisted they hadn't seen anything.
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Presenting stimuli to 1 visual field only:nude pin-up image
a nude pin-up image was presented to their LVF & participants would giggle or blush but couldn't say why
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Presenting stimuli to BOTH visual fields: ? and $ symbol
both symbols shown simultaneously, p's asked to say which one they saw and would say the $.When asked to draw with their left hand what they say, they drew the ?
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Tactile tests:
below the screen was a gap so p's could reach objects which had been placed in a bag but couldn't see. P's were unable to retrieve an object with their right hand if it had first been sensed with the left hand.
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Results:
info showed to only one hemisphere will only be recalled if shown to the same hemisphere again, visual material shown to the left hemisphere(RVF)can be described in speech & writing.
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Results: if visual material is shown to the right hemisphere...
...LVF, p's will deny seeing anything, but they are able to pick out the correct object with their left hand
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Results: if two different figures are shown to the hemispheres...
...then the p will be able to draw what they have seen in the left visual field with their left hand(right hemisphere)BUT, if asked what they've drawn they will say the object they saw in the RVF
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Results:if an object is placed in the right hand (left hemisphere)...
...it can be described and named.An object placed in the left hand (right hemisphere) cannot be described or named, but can be selected from other objects.
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Results: objects can be selected again...
...by the hand in which they were originally placed
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Conclusions:
there's evidence for lateralisation of brain function,language is associated with the left hemisphere,emotion associated with the right,split brain patients don't usually have problems irl because they can see stimuli for more than 1/10th of a second
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Strengths:
high levels,clearly demonstrated the lateralisation of function between the left and right hemisphere,although it's a small sample it was probably representative of the people who have had this operation
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Weaknesses:
tasks are low in ecological validity(p's would not face the same tasks irl), may not be possible to compare the brains of severe epileptics who have undergone brain surgery to the brains of 'normal' people
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Weaknesses:what is wrong with the sample?
There were only 11 participants which is a small to generalise from
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Other cards in this set

Card 2

Front

What are the two hemispheres of the brain connected by?

Back

The corpus callosum, a bundle of 200-300 million fibres.It allows epileptic discharges to travel from one hemisphere to the other, meaning epilepsy can involve the whole brain.

Card 3

Front

What did they do in the 1940's to reduce the severity of the attack?

Back

Preview of the front of card 3

Card 4

Front

What type of researcher was Sperry?

Back

Preview of the front of card 4

Card 5

Front

Sperry aim:

Back

Preview of the front of card 5
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