To investigate the effect of hemispheric disconnection, and to determine the lateralised functions of the hemispheres.
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sampling method?
Opportunity- patients of a neurologist Sperry was working alongside in LA.
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sample characteristics?
11 split brain right-handed patients who had been operated on to treat severe epilepsy, including male patient, seizure-free for 5 ½ years following the surgery, and a 30-year-old housewife, seizure-free for 4+ years following surgery. others to soon
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method?
Case study as many different tests of function were carried out over a long period of time (studied in-depth). Quasi with an assumed control group (the function of individuals with connected hemispheres was already known and so not tested).
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ethics?
Surgery carried out for the purpose of treatment- not for research. Patients gave informed consent
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procedure?
Commissurotomy: The corpus callosum (nerve fibres) connecting the two hemispheres were severed. The optic chiasm (connection between optic nerves from left and right eye) was left intact
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materials/ equitment? tachitoscope
a screen where images (in visual functioning tests) or words (in lingual tasks) were presented to one side of a fixation point, for 1/10th of a second, to avoid participants re-focusing and viewing information with both visual fields.
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materials/ equitment 2?tachioscope
One of the participant’s eyes was covered. Info to the left of the fixation point went to left visual field of eye and vice versa. There was also a gap under the screen, for participants hands to be concealed. Objects could be placed in the hands.
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main findings?
atients have two separate visual inner worlds (hemispheres have different perception as one can think in language and the other cannot, and they receive different visual information from the visual fields). Patients have a lack of cross-integration
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main findings 2? consciouness?
Split-brain patients seem to have two independent streams of consciousness, each with its own memories, perceptions and impulses, i.e. two minds in one body
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example consciouness?
-When different objects were presented to each hand, and then placed back in a pile behind the screen, the hands would search for their objects independently. If they picked up the object the other hand (and hemisphere) was searching for= put it back
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thrid main finding?
Contra-lateral control: each hemisphere controls the opposite hand and visual field.
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visual tests?
Information presented to the Right visual field, controlled by the left hemisphere, they could be described in speech and written, drawn, or picked from a selection of objects, with the right hand. If
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visual tests 2?
If the same information is presented to the Left Visual field, controlled by the Right hemisphere, the participant said they saw nothing, as the left hemisphere was controlling speech and had not processed the object.
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visual tests 3?
However, the participant could point to a matching picture/object, presented among a collection of pictures/objects, or draw it, with his left hand, controlled by the right hemisphere.
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tactile tests?
Objects placed in the right hand, controlled by the left hemisphere, could be described in speech, or written with the right hand.
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tactile tests 2?
If the same objects were placed in the left hand, controlled by the right hemisphere, which is not capable of producing language, participants could only make wild guesses about what they were holding, and often seemed unaware they holding anything
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latreralisation?
the left hemisphere predominantly controls language (particularly speech and writing) whereas the right hemisphere can only comprehend language. The right hemisphere can solve simple arithmetic problems and process emotion.
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laterlisation example?
When a ? was presented to the left visual field and a dollar sign to the right visual field
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laterlisation example 2?
which also processes information from the left visual field, but said they had drawn the ?, as the production of speech is controlled by the left hemisphere which saw the dollar sign in the right visual field.
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laterlisation example 3?
When plastic arithmetic symbols and numbers were presented to the left hand, controlled by the right hemisphere, it could do simple addition, and pick out the correct number with the left hand, from a selection.
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laterilisation example 3?
When a nude image was presented to the left visual field, the participant blushed or giggled but could not explain why.
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Other cards in this set
Card 2
Front
sampling method?
Back
Opportunity- patients of a neurologist Sperry was working alongside in LA.
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