0.10 Research support for lateralisation and localisation

who did research for hemispheric lateralisation

Sperry and Gazzinga

split brain research

what was the method used by Sperry and Gazzinga

visual information was presented to one hemisphere at a time (words)

objects were also placed in one hand to test tactile processing (objects)

what were the findings of Sperry and Gazzinga’s research 

each hemisphere has specialised functions, but normal behaviour like naming and recognising objects needs integration between them 

when an object was shown to the right visual field patients could name it verbally 

when object was shown to the left visual field the could not name it but could draw it or select it by touch

who did Sperry and Gazzinga’s research use

12 patients

who had their corpus callosum severed (brain cut in half) to treat epilepsy

meaning messages could not be passed across hemispheres 

evaluation points to Sperry and Gazzinga’s research 

• small sample size - population validity 

• differences within the small sample as it was severed slightly differently with each person

• 3rd variable - what if something else had been damaged

• correlation not causation 

who did research into localisation of speech and language function

Peterson et al

patient Tan - Broca

Wernicke

Kenyon et al

what was Peterson et al’s research

localisation of speech and language function

used PET scans

8 participants

• very small sample

what did Peterson’s research find

• Broca’s area was active during speech production tasks

• Wernicke’s area was active during language comprehension tasks

evaluation of Peterson’s research

small sample - 8

unethical - radioactive

describe Tan

patient studied post-mortem by Broca, trouble with speech production, found damage to what he named Broca’s area

but

brain changes after dealth

can’t study active brain

correlation not causation

what was the method for Kenyon et al’s research 

what repetition task in 14 healthy participants measured using FMRI

what were the findings of Kenyon et al’s research

activation in Broca’s area, bilateral sensorimotor cortice’s and cerebellum during speech production

evaluation of Kenyon’s research

• shows theory of Broca’s for speech production is reductionist

• small sample size 14, better than others

• FMRI’s very expensive