Sperry Case

Sperry (1968)

Aim: To show the behavioural and psychological effects when the brain is split into two by severing the corpus collosum. This is to prove that each side of the brain has different functions.

Method: Participants are patients who had epilepsy until they have undergone an operation by severing the corpus collosum. 

Design: Natural experiment

Procedure: 
Since each hemisphere receives information from the opposite side of the body, if images are presented visually, they would have to be presented at a duration of 1 tenth of a second so that the eye does not have enough time to refocus and therefore is sent to the opposite hemisphere. If tactile objects are presented, the information received by touch from one hand would be sent to the opposite hemisphere. 

Results
The results show that the separate hemispheres have different functions and abilities. If a visual is shown to the right eye, received in the left hemisphere, the person would be able to use speech to say what it is. However, if it was done in reverse, the person would not be able to say what the image is and can only be identified through pointing. This is when the visual is presented one at a time.
When visuals are presented both at once, the person can name what the image was if it was received through the left hemisphere, however, as for the right hemisphere, the only way to know is to draw the image out with the left hand.
Tactile stimuli - If information is received in the left eye and the person is needed to pick up the object, he would grab the correct one without knowing why. If it's the right eye, he would be able to pick out the object and know why he did so.

Evaluation
methodological validity - being a natural experiment, lack of control over variables.
Theoretical - Research has revealed many differences. Findings appear most in right-handed men. It must keep in mind that the left and right hemispheres share many functions that are highly integrated.

Applications: Implications for helping those with brain damage.