hemispheric lateralisation Flashcards
what is hemispheric lateralisation
the idea that two halves of the brain are functionally different and that certain mental processes are controlled by one hemisphere rather than the other
which two language centres are found in the left hemisphere (specific)
brocas area - left frontal lobe
wernicke’s area -left temporal lobe
what is the left hemisphere known for being dominant for
language
what is the right hemisphere known for being dominant for
visual motor tasks
why are motor skills not lateralised
because they appear in both hemispheres eg. motor area of brain is cross wired, right hemisphere controls movement on left side
why is vision not lateralised
each eye recieves light from the left visual field and right visual field. Left visual field transmits information to right hemisphere, right visual field transmits information to left hemisphere
why is split brain research useful in investigating lateralisation
split brain patients have their corpus collosum removed in order to reduce epilepsy. This prevents the two hemispheres from communicating with each other.
outline the methodology of sperrys research
11 people who had split brain operations were studied using special set up where image could be projected into right visual field and then the same/ different image could be projected into the left visual field. pps stared at fixation point for 1/10th of a second, pps then asked what they could see or asked to draw what they could see.
what did sperry find and why
picture shown to right visual field pps could describe what they could see as this involved the use of the left hemisphere where the language centres are located. could not describe picture in left visual field. However could select an object using their hand which matched the picture, as involved use of right hemisphere which contains motor skills.
what is a strength of sperry’s methodology (AO3)
method was highly standardised and high in validity. if looked for more than 1/10th of a second the eyes would move so that both the L and R visual field process the same information and therefore both hemispheres would become aware of the stimuli via optic chiasm. By identifying the length of time sperry could be sure that he was only testing one hemisphere at a time therefore the study is high in internal validity.
as a result of sperrys standardised procedure…. (AO3)
his research can be replicated by other people, for example Gazzaniga reported the case of a californian women who had a split brain operation ,was shown a picture of a naked women in her left visual field, she giggled with amusment but when asked why she could not describe why. therefore findings about hemispheric lateralisation are consistent and high in validity.
(AO3) what is the main issue with generalising findings of split brain research to support nomothetic theory ie. that all language centres are in the LH
samples consist of atypical individuals who have undergone rare surgery. Cannot be sure same results will be produced without surgery should have another control group with epilepsy but no surgery in order to generalise. As the use of the control group would validate it was the corpus collosum that caised the changes in split brain functioning not their epilpepsy.
what are the similarities and differences of the hemispheres
verbal responses processed by left hemisphere
emotion processed by right
comprehension and understanding processed by both
left and right may have different memory stores as could only identify by touch with hand that first touched the object.
