Sperry Flashcards
What was the background to Sperry?
Experiment on people who had already had their corpus collosum severed for severe epilepsy.
Human brains are divided into 2 hemispheres, left for language and right for maths etc.
(Late rises function)
What was the aim of this study?
To investigate effects of hemisphere deconnection and to show that each hemisphere has different functions
Who were the participants?
11 split brain patients as history of advanced epilepsy.
What method is used in this study?
Quasi experiment. Comparing performance of people with and without inter-hemisphere connection.
IV: hemisphere deconnection or not
DV: participant performance on task
Describe 1 of the tasks
Response to visual information: blindfolding one eye and asking to fixate on middle point of screen, they then project stimulus on either right or left hand side of point for less than 1/10th of a second. Ensuring the it wouldn’t spread to both sides of visual field.
In left visual field they should be able to name stimulus as left hemisphere associated with language.
Describe another task used (2)
Tactile information: presenting stimulus to one of hands patient and couldn’t see stimulus and asked them to name it, if presented in left hand they shouldn’t be able to name it.
What are the results of this study?
When represented with same stimulus in other visual field they act if never seen before.
Not give a description that was presented to left hand side of visual field, image not noticed, they could respond nonverbally bY by pointing with left hand to a matching picture.
If 2 symbols presented simultaneously 1 on either side of the visual field (dollar sign on left and question mark on right) the participant asked to draw with left hand they would draw the dollar sign but name it as a question mark.
If object is in right hand they can name in speech or writing. If placed in left hand they would make a wild guesses or unaware object was present. However if taken and put into a bag scrambled they would retrieve it with left hand.
Laters satin function example: when 2 different objects placed in each hand then scrambled with other items, each hand looked for own object and split hemisphere patients could perform double tasks in parallel (highly unusual tasks performed well)
What was the conclusion of this study?
When hemispheres are disconnected 1 half of brain does not know what other half is doing
The left hemisphere is specialised for speech in writing and for the organisation of language, it can communicate visual experiences of right visual field and experiences of right half of the body.
The right hemisphere is mute and cannot speak or write, but can show non-verbally that mental processes are present.
