split brain

Question 1

background info of Sperry’s research

Answer 1

• two hemispheres connected by corpus callosum
• allows info recieved from one hemisphere to be sent to other
• individuals had corpus callosum cut down middle to separate hemispheres + control epileptic seizures to see extent of hemispheric lateralisation

Question 2

Sperry’s aim?

Answer 2

to see the extent the two hemispheres are specialised for certain functions

Question 3

what method did Sperry use?

Answer 3

• sample of 11 split brain patients
• fixate on dot in centre of screen while info was presented to either right or left visual field
• asked to make response:
  with left hand (control by right hem) or verbally (control by left hem)

Question 4

Sperrys results overview (3)

Answer 4

1. describing what see-> word shown to RVF processed by LH (lang centre) so say word, word to LVF no lang centre= ‘nothing there’ + draw with left hand RH
2. recognition by touch-> cant name objects projected in LVF processed by RH, can select matching object using left hand. ball in RVF say what saw
3. composite words-> ‘key’ to LVF so chose key with left hand, ‘ring’ to RVF so speak what saw

Question 5

conclusions from Sperry?

Answer 5

• left hemisphere is dominant in right side of body + language centres
• right hemisphere is dominant in controlling left side of body
• supports hemispheric lateralisation bc shows LH controls right side + RH controls left side. opposite hemispheres control opposite sides of body.

Question 6

how does Sperry demonsrtae lateralised brain function?

Answer 6

• concluded that LH controls right side of body + RH controls left side of body where left geared towards verbal tasks wheras right geared towards performing spatial tasks
• supports idea of hemipsheric lateralisation as shows each hemipshere has specific functions
• therefore key contribution to our understanding of brain proccesses

Question 7

how is Sperry’s methodology a strength?

Answer 7

• experiements involved specialised and standardised procedures
• presented visual info one HF at a time by covering one eye. image flashed for 1/10th of second so wouldnt have time to move eye across image
• well controlled as could vary aspects of basic procedure
• counter-> lacks ecological validity as doesnt rep real-life, artifical task + setting

Question 8

what are the issues with generalising Sperry’s research?

Answer 8

• 11 split brain patients, unusal sample as had epiletic seizures
• may have caused unique changes in brain influencing findings
• some patients experienced more disconnection of the two hemispheres as part of surgical procedure
• control group= no history of epilepsy- inappropriate as comparing diff brains as epilepsy is cofounding variable. better= epilepsy and no split brain
• therefore difficult to gen findings as highly unique + lacks val due to control group

Question 9

why may Sperry’s differences in function be overstated?

Answer 9

• overemphasises and oversimplifies functional distinction between LH and RH
• neuroscientisits contended that distinction between verbal and non-verbal is less clear cut than this.
• normal brain the 2 hemispheres are constant communicating when performing tasks.