sperry
- Created by: Soancosoanco
- Created on: 04-02-20 09:16
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- Sperry
- Theory
- The brain hemispheres mirror each other, but each have a functional localisation
- The primary motor cortex is situated in the frontal lobe. Right hemisphere receives information from the activities of the left side of the body and vice versa
- Split-brains reveal the ‘true’ nature of the two hemispheres because they can only work independently
- Background
- Previous research showed numerous behavioural effects, but they were much less severe than other cerebral surgeries
- Sperry set out to show that each hemisphere possesses an independent stream of conscious-ness and has its own chain of memories that are inaccessible to the other
- Research Method
- Quasi/natural experiment because the IV wasn't directly manipulated
- Ps' with split-brains had hemisphere deconnection. No controls were necessary because the visual fields/ hemispheres in non split-brain individuals was already known
- IV: having a split brain or not
- DV: ability to perform visual/tactile tests
- Can be considered a collection of case studies
- Sample
- 11 patients who had their corpus collosum commis-surated to control severe epliepsy
- 2 patients had surgery over 4/5 years before the study was conducted
- 9 patients had surgery not long before the study
- Procedure
- Ps' had one eye covered, and stared a fixed point in the centre of the tachistoscopeVisual stimuli were back-projected at 1/ 10 of a second or less – too fast for eye movements to get the information into the wrong visual field. Everything projected to the left of the screen is given to the LVF/right hemisphere and vice versa
- Objects were placed where ps' could not see, into their right/left hand or both. Information about objects in the left hand is processed by the right hemisphere and vice versa
- Participants did visual and tactile tests
- Results
- Information shown to one VF could only be recognised if shown to the same VF
- Information presented to the RVF can be described in speech/ writing with the right hand. If the same info is presented to the LVF, the ps insist they did not see anything/there was only a flash of light on the left side, it could not be described. However ps' could point with their left hand to a matching picture/object
- If different figures were presented simultaneous-ly to different VFs eg. $ to the LVF and ? to the RVF, the ps could draw the $ sign with their left hand but reported that they had seen a ?
- Objects in the right hand could be described in speech/ writing with the right hand. If the same objects were placed in the left hand, ps' could only guess/were unaware they were holding anything
- Objects felt by one hand were only recognised again by the same hand
- If objects were placed simultaneous-ly in each hand and then hidden, hands only selected their own object
- Conclusions
- People with split brains have two separate visual inner worlds
- Split-brain patients second hemisphere does not know what the first hemisphere has been doing
- Split-brain patients seem to have two independent streams of conscious-ness
- Theory
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