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What was the aim of Sperry's study?

To investigate the effects of a deconnection of the two hemispheres in the brain, and show that each hemisphere has different functions.


What research method and design was Sperry's study?

The design was a quasi-experiment which compared split-brain subjects with 'normal' subjects in laboratory tests.


Outline the participants of Sperry's study.

-11 patients
-Already experienced commissurotomy prior to study
-Opportunity sample
-All subjects had history of severe epilepsy


How did Sperry investigate one visual field in his visual investigations?

-Participant has covered one eye
-Told to look at fixation point at centre of computer screen
-Image projected on either left or right side of fixation point for one-tenth of a second


Why were images presented for one-tenth of a second?

To prevent the information going to the wrong half of the visual field if the subject moved their eye.


Which hemisphere of the brain would receive information from the left visual field?

The right hemisphere.


How did Sperry investigate both visual fields at once in his visual investigations?

-Subject looks at fixation point on screen
-Two images flash simultaneously either side of fixation point
-One image sent to each hemisphere
-Participants then asked what they had seen - would say what was presented in right visual field
-Participants then given pen in left hand and asked to draw what they had seen - would draw what was presented in left visual field, but not know why they had drawn it


What is each hemisphere of the brain meant for?

-Left hemisphere is the centre of logic, maths, analysing etc.
-Right hemisphere is centre of creativity, philosophy, imagination etc.


Describe the 3 tactile investigations with one hand.

-Participant's hands hidden from view behind screen.
-Subject asked to find object corresponding to what they have seen on the screen.
-Object placed in one hand, and are asked what they have been given
-Object placed in one hand, and are then asked to point at what they were given


Describe the tactile investigation of both hands at once.

-Participant given two different objects, one in each hand, and then objects are taken away.
-Participant then asked to find the objects by touch from a pile of items
-Subject then asked to say what they have just held


Describe the 3 ways in which the right hemisphere was tested.

-Left visual field presented with object on screen. Subject asked to pick out similar objects by touch
-Simple mathematical problems presented to left visual field. Subject asked to sort objects by shape, size or texture using left hand
-Array of shapes presented to both visual fields. In the middle of this array is a nude picture, in left visual field only. Subject then asked if they saw anything other than shapes


What did Sperry find to do with memory when participants were shown an image in one visual field?

Would only recognise image as one they had already seen if it was shown again to the same visual field.


What did Sperry find when participants were shown an image in the right visual field?

-Subject able to say what they saw
-Could identify it from an array of pictures shown to the right visual field
-Could find it with their right hand.


What did Sperry find when participants were shown an image in the left visual field?

-Subject unable to name it, but could draw it with eyes closed with their left hand.
-Could identify it from an array of pictures shown to the left visual field by pointing at it
-Could find it with left hand


What did Sperry find when images were presented to both visual fields?

-Subject could say what they saw in right visual field, but would be unaware they had seen anything else.
-Could draw what was in left visual field with their left hand, but had no knowledge of seeing it


Identify two results of the tactile investigations.

-Subject had no problem identifying an object by name if put in right hand
- When objects placed in one hand, participant could point to what object was with that hand


What did Sperry find when participants were shown an images to the right hemisphere (in the left visual field)?

-Right hemispheres able to carry out simple mathematical problems
-Left hands able to sort objects by shape, size and texture
-Participants would giggle or look embarrassed when picture of nude appeared, but would not know why.


What are the main conclusions of Sperry's study?

That the brain consists of two seemingly independent hemispheres, each with it's own consciousness.