Sperry's study of split-brain patients

Aims:

• To test the effects of hemispheric deconnection in humans.
• To investigate whether cognition, including perception and memory, differs between the hemispheres.
• The extent to which the hemispheres would normally interact to achieve cognitive functions. 

Participants:

• 11 patients with epilepsy that had had a commissurotomy 
• They were recruited through opportunity sampling. 

Design:

• This was a lab experiment, that resembeld a collection of case studies using repeated measures design.
• The IV was the manipulation of the hemisphere.
• The DV was the individual's performance in tests of cognition.

Procedure:

• The general procedure was to expose one or both hemispheres to a stimulus and to elicit a response. 
• Stimuli was visual, tactual or auditory.
• Controls were employed to reduce input from extraneous variables. 
• Time was measured precisely to ensure that gaze could not be shifted to view the stimulus in both visual fields. 

Results:

• Both quantitative and qualitative data was gathered. 
• Quantitative was in the formor yes/no results - whether they could complete the task.
• Qualitative data was descriptions of the participants sensations and their verbal responese. 
• Pictures of objects were recognised only if presented to the same visual field.
• Participants could only describe objects presented to the right visual field.
• Participants could only write the object if presented to the right visual field. 
• Participants could correctly point to an object presented to the LVF. 

Conclusions:

• In split-brain patients, perception in each hemisphere is independent. 
• If information passes only to the right visual field, individual's cannot respond in speech or writing. 
• In split-brain patients, memory in each hemisphere is independent.
• Information from one visual field is remembered by only that hemisphere and cannot be accessed by the other.
• In every day life, split-brain patients are not impaired.