Split-brain Research into Hemispheric Lateralisation

Question 1

what is hemisphereic lateralisation?

Answer 1

certian mental procees and behaviours are controlled and dominated by one hemisphere rather than the other

Question 2

how are the two sides of the brain connected?

Answer 2

a bundle of nerve fibers called the corpus callosum

Question 3

who did sperry (1968) study?

Answer 3

a group of epileptics whose corpus collaosum was cut (commissurtomy)

Question 4

what was sperry’s unique procedure to test his split brain patients?

Answer 4

an image or word is projected to a patients RVF (processed by LH) and another image shown to the LVF (processed by RH)

Question 5

why did sperry use this procedure?

Answer 5

• in his patients the information cannot be conveyed from the chosen hemisphere to there other
• therefore, sperry could cleary define which behaviours were controlled by which hemisphere

Question 6

what 3 tests did sperry use in his study?

Answer 6

1. describing what was seen
2. recgnition by touch
3. matching faces

Question 7

Sperry’s findings - describing what you see

Answer 7

objects shown:

• RVF - patient easily describes what was seen
• LVF - pateint says ‘there’s nothing there’

Question 8

why couldn’t describe what they saw in LVF?

Answer 8

• RH lacks language centres
• messages recieved by RH are normally relayed via corpus collosum to language centres in LH

Question 9

Sperry’s findings - recognition by touch

Answer 9

objects shown LVF:

• patient could not verbally identify what they had seen (LH needed for this)
• could understand what the object was (using RH) and select the corresponding object .
  
  • eg ashtray selected in response to picture of a feg

Question 10

Sperry’s findings - matching faces

Answer 10

• LH dominated the verbal desription
• RH dominated the selection of matching picture

Question 11

what were sperry’s overall findings?

Answer 11

• LH - is more geared towards analytic and verbal tasks (the ‘analyser’)
• RH - is more geared towards spatial tasks and music (the ‘synthesiser’)

Question 12

what does split brain research show?

Answer 12

certain functions are lateralised

Question 13

why was Sperry’s research so methodological?

Answer 13

he carefully standardised procedure - patients stared at a fixed point with one eye and an image was flahsed up for 0.1s

Question 14

what was the significance of an image only being flashed to one eye for 0.1s?

Answer 14

patient had no time to move their eyes over the image and spread the information across both sides of the visual field (susbsequnetly both sides of the brain)

Question 15

why might sperry’s research lack generlisability?

Answer 15

• only 11 patients took part in all variations
• they all had history of seizures
  
  • may have caused unique changes to brain