Sperry Flashcards
What area is this
Biological
What was the aim of the study
To show that each hemisphere in split brain patients:
- possesses an independent stream of conscious awareness
- has its own sele rate chain of memories that are inaccessible to the other
What is the research method
Natural/ quasi experiment
What is the experimental design y
Independent variable
What are the independent variables
Hemisphere disconnection / or not
No actual control group was necessary for comparison because the functions and abilities of yeh visual fields and hemispheres in non split brain individuals was already known
What was the dependent variable
Performance on visual and tactile tasks
Who were the ppts
11 severe epilepsy patients who has their corpus callosum cut as a treatment of their condition
Ranging from 5 to 1 year prior to the study
Atleast one woman
What are the general observed effects of commissurotom
Reduced epileptic seizures
Lack of effect on ordinary behaviour
No effect on intelligence or personality
What was the procedure of the visual field test
Ppts cover one eye and stare at a fixation point
An image is presented to either the far right or far left visual field for 1/10 of a second
They are asked to name and describe the image
What were the results of the visual field
Object presented in far right visual field - information goes to the left hemisphere- object can be described in speech and writing
Vice versa, but ppt cannot describe the object in speech or writing but can draw it, has memory of it
Ppt recognised a picture seen in one half of the visual field: they only recognise it again if it appears in the same half field
Therefore, each hemisphere has its own visual image and memory
What was the procedure of the tactile tests and results
Participants have both eyes covered
Object placed in right hand - can be described verbally
Object placed in left hand - can’t be described or written about but can be retrieved from a. Bag of objects by same hand as used for initial identification
No cross retrieval
Simultaneous presentation - 1 object placed in 1 hand, a different object placed in the other hand. Ppts only verbally state what is in their right hand
Each hand independently seeks out its own object from a bag of mixed objects
Specific tests of right hemisphere
Procedure
Using the visual field apparatus different stimuli were presented to the far left visual field only, therefore isolating the right hemisphere
Simple maths problems were shown in the far left visual field
Results: ppts could categorise the objects
A written word eg eraser was shown in far left visual field
Results: ppts could point to a matching picture or pick out an eraser from a bag, with left hand only
Conclusión
Each hemisphere appears to work independently having its own sensations, perceptions, learning experiences, impulses to act and chain of memories which are inaccessible to the other hemisphere
Each hemisphere functions independently and had no knowledge of what the other is doing
What are the functions of the left hemisphere
Controls speech and writing
Centre of organisation and comprehension of language
Received info about eight side of body and can communicate those experiences
Communicates about general cognitive activity common to both hemispheres
What are the functions of the right hemisphere
Mute, can’t express itself verbally or in writing
Receives info about left side of the body
Can do simple logic and reasoning, has the capacity for mental association can do simple arithmetic problems
Understands both written and spoken words
Can categorise objects into groups by touch in the basis of shape, size and texture
