Core studies - Biological Psychology - Sperry study Flashcards
What is the Corpus Callosum
The region of the brain that connects the two hemispheres in order for them to communicate with one another
What are Hemispheres
The two symmetrical halves oft he brain, left and right, which both have different functions
What is Hemispheric Disconnection
- The split brain operation in which the corpus callosum is severed in order to stop the communication between hemispheres and as a result they act independently
- Given to severe epileptics to stop the ‘storms’ of communication in their brain that cause the seizures
What is Lateralisation of Function
- The belief that the two hemispheres of the brain have different functions
- The left is in charge of language and the right is in charge of spatial awareness
What is Contralateral Control
The belief that the left hemisphere controls the right side of the body and the right hemisphere controls the left side of the body
What is a Tachistoscope
The apparatus used in Sperry’s study to allow the visual stimuli to be presented to the participants
Aim
To record the psychological effects of hemispheric disconnection and to find evidence for lateralisation of function in ‘normal brains’
Sample
- 11 people
- Had the split-brain surgery
- Previously had severe epilepsy
Sampling Method
Opportunity sampling
Research Method
Quasi experiment
What was the IV
Whether the participants had a split brain or not
What was the DV
Their (participants) performance on visual and tactile tasks
What were the 4 tasks
- ONE VISUAL FEILD TASK
- BOTH VISUAL FEILDS TASK
- TACTILE ONE HAND TASK
4.TACTILE BOTH HANDS / DUAL PROCESSING task
Main procedure
- Each p was studied alone
- The p had one eye covered, and was asked to look at a fixed point in the centre of the screen on the Tachistoscope
- Visual stimuli were then projected onto the screen, either to the right visual field of the left visual field
- The images were shown for 0.1 seconds each so the p had no time to change their visual field
What was the procedure for the ONE VISUAL FEILD task
- Each p was shown a visual stimulus on the screen whilst focusing on the central fixation point
- They were shown one image in one visual field
- They were shown the images for 0.1 seconds
- After, they were asked to name what they had seen
What were the result for the ONE VISUAL FEILD task
- When p’s were shown an image in their RVF this image would be processed in the left hemisphere which is in charge of language therefore the p’s would be able to say and draw what they had seen
- When p’s were shown an image in their LVF this image would be processed in the right hemisphere which is in charge of spatial awareness therefore they wouldn’t be able to say the word, but they could draw it
What was the procedure for the BOTH VISUAL FEILDS TASK
- Each p was shown a visual stimulus on the screen whilst focusing on the central fixation point
- They were shown two different images, one in each visual field at the same time
- They were shown the images for 0.1 seconds
- After, they were asked to name what they had seen
What were the results for the BOTH VISUAL FEILDS TASK
When p’s were asked to draw what they had seen they would draw the image from the LVF. But if asked to say what they had seen they would say the image seen in the RVF
What was the procedure for the TACTILE ONE HAND task
- Each p was given an object in one hand
- The p’s were either asked to say or write down what was in their hand
What were the results for the TACTILE ONE HAND task
If the item had been placed in the p’s right hand, it could be identified in the left hemisphere and be written with the right hand
What was the procedure for the TACTILE BOTH HANDS / DUAL PROCESSING task
- The p works with their hands out of sight
- They would be given two different objects, one in each hand and then the objects are taken away
- The p is then asked to find the objects by touch from a pile of items or are asked to say what they have just held
What were the results for the TACTILE BOTH HANDS / DUAL PROCESSING task
P’s were able to find the objects by touch but only by the hand where the object was first placed. If the hand that touched the object was not the hand where it was originally placed then it would reject the object, almost as if the p had never held the object before
What were the conclusions for the TACTILE BOTH HANDS / DUAL PROCESSING task
This suggests that the two hemispheres are working separately so when they searched for the object they would only recognise it if it was in the same hand
Further results from the study
- Hemispheric disconnection did not appear to affect the p’s intelligence or their personality
- Patients however experienced short term memory deficits, fatigue more quickly in reading, limited concentration spans and orientation problems after the split brain surgery
Conclusions
- Split brain patients appear to have two independent streams of consciousness, each with its own memories, perceptions and impulses. This supports the argument of lateralisation of function
- People with split brains have two separate visual inner worlds each with its own train of visual images
- Split brain patients have a lack of cross integration where a second hemisphere does not know hat the first hemisphere has been doing
Conclusion 1
Split brain patients appear to have two independent streams of consciousness, each with its own memories, perceptions and impulses. This supports the argument of lateralisation of function
Conclusion 2
People with split brains have two separate visual inner worlds each with its own train of visual images
Conclusion 3
Split brain patients have a lack of cross integration where a second hemisphere does not know hat the first hemisphere has been doing
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