Split brain research into hemispheric lateralization

Question 1

What is a commissurotomy?

Answer 1

A surgical procedure in which the corpus callosum and other tissues connecting the hemispheres are split- usually used to control severe epileptic seizures

Question 2

Generally, how were Sperry’s studies structured?

Answer 2

Information is provided to one hemisphere of the brain and the participant is asked to reproduce the information either verbally (spoken) or visually (drawing or matching)

Question 3

What did Sperry find in the ‘describing what you see’ variation of his study?

Answer 3

Patients could describe what they saw in their right visual field but not their left visual field

Question 4

What did Sperry find in the ‘recognition by touch’ variation of his study?

Answer 4

Patients could not describe something processed by their right hemisphere but could match it in their left hand (whether they could see it or not)

Question 5

What did Sperry find in the ‘composite words’ variation of his study?

Answer 5

If a different word was shown in both visual fields (KEY | RING) the participant would say the right word (ring) but match the left word (key)

Question 6

What did Sperry find in the ‘matching faces’ variation of his study?

Answer 6

• Participants were only able to consistently match a face to one seen in their left visual field
• When a different face was shown in each visual field, the one in the left visual field was matched but the right visual field was described

Question 7

What are some methodological strengths of Sperry’s research?

Answer 7

• Everything was standardised

- Images were only shown for one tenth of a second to avoid eyes looking at both images

Question 8

Comment on the external validity of Sperry’s findings

Answer 8

• There were only 11 participants
• The participants had all had a history of severe epileptic seizures
• Participants may have had hemispheres disconnected different amounts
• The control group had no history of epilepsy