hemispheric lateralisation Flashcards
what is hemispheric lateralisation ao1
the idea that two halves of the brain are functionally different and certain processes or behaviours are controlled by one hemisphere rather than the other.
right side of the brain processes information from the …. side of the body ao1
left (e.g. visual info from the left eye)
left side of the brain processes info from the ….. half of the body ao1
right (e.g. visual info from the right eye)
name one thing that is usually processed by the left hemisphere ao1
language
name one thing that is usually processed by the right hemisphere ao1
face recognition
who are split brain patients ao1
a unique group of patients who had a commisurotomy - where the corpus callosum is severed so that the two hemispheres are separated and don’t communicate with each other. this was done to control severe and frequent epileptic fits.
what did sperry discover ao1
studied split brain patients and compared them to patients with no hemisphere separation. sperry devised a procedure where a word or picture is projected into the left or right visual field. this is then dealt with by the opposite hemisphere of the brain and the information isn’t shared between the two hemispheres.
what was sperrys tactile procedure ao1
tactile taks (taks with objects) were carried out with the Ps hands underneath a screen so the Ps themselves couldn’t see what they were doing. they had to use ‘feel’ only.
what were the findings from when they were describing what they see ao1
when a picture of an object was shown to a patients right visual field they could easily describe what was seen. when a picture was presented to the left field of vision they could not describe it (they often reported that there was nothing there).
what were the findings for recognition by touch ao1
if they were shown an object in their left visual field (right eye) they can pick up the object (from a selection hidden behind a screen) with their left hand as the visual image and left hand are controlled by the right hemisphere. they could not verbalise what they were selecting though.
what were the findings for composite words ao1
if two words were presented simultaneously, one on either side of the visual field (for example key to the left visual field and king to the right visual field) they would say ring as that is processed by the left hemisphere and they would be able to pick up the key with their left hand as that was processed by the right hemisphere
what were sperry conclusions ao1
it seems that in these patients the hemispheres of the brain process information separately. hemispheres do seem to have differing functions (e.g. language left and drawing ability right)
what did szaflarski et al (2006) propose
found that language became more lateralised to the left hemisphere with increasing age in children and adolescents but after the age 25, lateralisation actually decreased with each decade of life.
what does this suggest
lateralisation changes with normal ageing.
why might this be
because of that using the extra processing resources of the other hemisphere may in some way compensate for age-related declines in function. this implies that a lateralised brain is in fact only a feature of young adults and not true for everyone.
