lateralisation Flashcards
What is hemispheric lateralisation?
Hemispheres are functionally different, one function controlled by one side
Who investigated hemispheric lateralisation using split brain research?
Sperry
Describe the participants of Sperry’s research
Undergone commissurotomy
Corpus callosum which connects 2 hemispheres cur down the middle to control epileptic seizures
Describe Sperry’s procedure
Image or word projected to patient’s right visual field and another to the left visual field
Information could not be conveyed from one hemisphere to the other
What were Sperry’s 4 findings concerning?
Describing what you see
Recognition by touch
Composite words
Matching faces
Describe describing what you see
Right visual field - easily describe what was seen
Left visual field - can’t describe, said nothing was there
Language in left hemisphere
No language centres in right hemisphere
Describe recognition by touch
Left visual field - could not attach verbal labels but could select matching object using left hand
Placed behind screen so not seen
Left hand - could select object associated with object from left visual field eg cigarette and ashtray
Could understand object
Describe composite words
Word presented on either side of visual field
Key on left ring on right - select key with left hand and say word ring
Left VF = right hemisphere = left hand
Describe matching faces
Right hemisphere dominant in facial recognition
Asked to match face from series of faces
Picture processed by right hemisphere consistently selected
Picture processed by left hemisphere ignored
Picture made of two halves of a face - one to each hemisphere - left hemisphere dominated verbal description, right hemisphere dominated matching the picture
Evaluation - demonstrated lateralised brain functions
Sperry - concluded left hemisphere is analytical and right is good as spatial tasks
Right hemisphere - only rudimentary words but contributes emotionally
Left - analyser
Right - synthesiser
Evaluation - methodological strengths
Standardised procedures
Image flashed for a split second - no time for eyes to move across
Well controlled
Evaluation - theoretical basis
Prompted debate about communication between hemispheres
Pucetti - hemispheres are functionally different and represent form of duality - we are all two minds
Argued against - two hemispheres are both involved
Evaluation - issues with generalisation
Unusual sample of 11
History of epilepsy - may have caused changes
Some had more split between hemispheres than others
Control group differed in 2 ways - non epileptic and had a corpus callosum
Evaluation - overstated differences in function
Pop-psych - overemphasises distinctions
Less clear cut than stated
Hemispheres in constant communication
