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Psychology AS (OCR)
Sperry `split brain'
Our brain is made of parts called the left and right hemisphere. The
right hemisphere mostly controls the left side of our body and the
left hemisphere controls the right side of our body. This system is
called the contralateral control. Sperry used split brain patients
(patients who had had both hemisphere disconnected due to a
history of advanced epilepsy), and what would happened if both
hemisphere weren't able to communicate with another. Would
speech and vision be affected?
The aim of this study was to investigate the effects of hemisphere disconnection and show that each
hemisphere had different functions.
11 epileptic patients who had undergone the surgery which involved cutting the corpus collossum
which is the bundle which brings attaches both hemispheres together.
9 had the surgery shortly before the paper was produced whilst 2 had the surgery some time ago.
The participants had experienced some side effects after the surgery as they had problems with
short term memory and concentration span but there were no problems with their personalities or
Independent variable: presence or absence of brain surgery.
Dependant variable: subject's performance on a variety of tests.
Method and design:
Can also be a called study methods as in depth investigation were made about the 11 participants.
Sperry used a standardised procedure in which he asked the participants to take perform a range of
tasks. The performance in these tasks was compared with those with no hemispheric deconnection.
One of the test involved sending information only to one of the participant's hemisphere, eg:
-Visual test: stimulus was presented to one or both visual fields for 1/10 seconds or less and
participants had to state what they saw. The presentation was so small to ensure that the participant
did not have the time for eye movement as this would spread the information across both side of the
visual field and therefore across both sides of the brain.
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Tactile tests: objects were presented on the right hand and to the left hand. Different object were
presented to both hands and participants were asked to name it. If the stimulus us presented to the
participant's left hand the participant should not be able to name the stimulus
Tests were carried out in laboratory condition, using specialised equipment and were highly