Sperry (1968)

Question 1

Theory

Answer 1

The left hemisphere of the brain is said to control language, logic and problem solving.

The right hemisphere of the brain is said to cont creativity, spatial awareness and emotion.

The left hemisphere controls the right side of the body and the right hemisphere controls the left side of the body.

Question 2

Aim

Answer 2

To investigate the effect of severing the corpus callosum, disconnecting the hemispheres, and map lateralisation, showing that each hemisphere has different functions.

Question 3

Participants

Answer 3

Opportunity sample of 11 split-brain patients.

Question 4

Procedure - Visual

Answer 4

With 1 eye covered, the participant centres their gaze on a fixed point in the centre of an upright translucent screen. Visual stimuli were arranged in a standard projector and shown for a tenth of a second or less. Everything projected to the left visual field would be perceived by the right hemisphere and vice versa.

Question 5

Procedure - Tactile

Answer 5

Below the translucent screen was a gap so participants could reach objects but not see their hands. Objects were then placed in the left/right hand. Those placed in the left hand would be processed by the right hemisphere and vice versa.

Question 6

Results - Visual

Answer 6

1. 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 i.e. the information could not be described in speech or writing. However, the participant could point with his left hand (RH) to a matching picture presented among a collection of pictures
2. If the $ was flashed to the LVF and a ? to the RVF at the same time. The participant would be able to draw the $ with their left hand without looking. However, when they are asked about what they have drawn, they say that they have drawn the ?
3. When participants were flashed two words at the same time e.g. ‘foot’ and ‘ball’. When asked to say the full word that they had seen the participant is only able to say the word ‘ball’
4. If the word foot ball was shown so that foot was shown to the LVF, a ‘foot’ could be drawn with the left hand. The RVF would see ‘ball’ so the participant would be able to say or write that they had seen the word ‘ball’.

Question 7

Results - Tactile

Answer 7

1. 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.
2. 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.
3. Participants can retrieve an item from a grab bag with the same hand the item was originally placed.

Question 8

Conclusions

Answer 8

1. People with split brains have two separate visual inner worlds, each with its own train of visual images.
2. Split-brain patients have a lack of cross-integration where the second hemisphere does not know what the first hemisphere has been doing.
3. 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.