Sperry

• Background-Left hemisphere responsible for language+lproblem solving,+ right side of our body The right hemisphere responsible for creativity,emotion and left side of the body. Split-brain patients reveal the nature of the two hemispheres because a commissurotomy which disconnects the two hemispheres which means they can only work independently.
• Aim: using split-brain patients, to show that each hemisphere: 1- Possesses an independent stream of conscious awareness. 2-Has its own separate chain of memories that are inaccessible to the other
•  quasi/natural experiment, Participants with split-brains had already undergone hemisphere disconnection to reduce severe epilepsy,Opportunity sampling ,
• 11 patients from America who had undergone a commisorotomy to cut their corpus callosum in an effort to control severe epileptic convulsions that could not be controlled by medication’.
• Presenting visual information: The participant, with one eye covered,looks at a fixed point in the centre of an upright translucent screen they.were arranged in a standard projector and were then back-projected at 1/10 of a second or less – too fast for eye movements to get the information into the wrong visual field.
• Everything projected to the left visual field would be received by the right hemisphere. Everything presented to the right visual field would be received by the left hemisphere.
• Information presented to the RVF could be described in speech and writing (with the right hand). If the same information is presented to the LVF (RH), the participant insisted he either did not see anything or that there was only a flash of light on the left side. However, the participant could point with his left hand (RH) to a matching picture presented among a collection of pictures

• Presenting tactile information: Below the translucent screen there was a gap so that participants could reach objects but not see their hands. Objects were then placed in either the participant’s right / left hand or both hands. Information about objects placed in the left hand is processed by the right hemisphere and vice versa. Participants undertook a variety of both visual and tactile tests. This apparatus is called a tachistoscope. Sperry also conducted a variety of other tests which highlighted the lateralisation (i.e. the role of each hemisphere of the brain)
• If an object is placed in the right hand, it can be said, written or found in a grab bag i.e. when the pencil was placed among other objects with the same hand it has been placed in.
• The participant will be able to verbally recall what they have in their right hand. However, when the same object is placed in their left hand, they will make wild guesses as to what it is. They would only be able to pick it out of a grab bag to identify it.
• Participants can retrieve an item from a grab bag with the same hand the item was originally placed.

Conclusions:

• ​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 the second hemisphere does not know what the first hemisphere has been doing.
• Split-brain patients seem to have two independent streams of consciousness, each with its own memories, perceptions and impulses i.e. two minds in one body.