Hemispheric lateralisation Flashcards
how many participants were in sperrys study?
11 split brain patients
what was procedure 1 of sperrys research- describing what you see
the participant was shown an object to their right visual field and asked to describe it.
they were then shown an object to their left visual field and asked to describe it
what were the findings of sperrys procedure 1 - describe what you see
the ps could describe objects shown to their right visual field because they use language processing in their left hemisphere.
they couldnt describe objects shown to their left visual field and reported there was nothing there
what was sperrys procedure 2 ?
recognition by touch
objects were placed behind a screen so that the patient could not see them
patients were then shown an object to either the left or right visual field
what were the results of sperrys procedure 2?
When an object was presented to the left visual field they could not describe it but could select matching object from behind the screen
what was sperrys procedure 3 ?
ps were shown 2 words simultaneously one on either side of the visual field
what were the results of sperrys procedure 3 ?
the p would write the word from the left visual field with their left hand
say the word from their right visual field
e.g key and ring
write key
say ring
what was sperrys procedure 4 - mathcing faces
a composite picture of 2 faces was shown
ps had to select the picture they saw from a line up
what were the results of sperrys procedure 4 ?
the patients selected the face that was presented to their left visual field (right hem processed it )
picture presented to right visual field was ignored
what did sperry conclude were the functions of left hem?
controls speech
production and language
logical thinking
numeracy
what did sperry conclude were the functions of right hem?
controls facial recognition
empathy
hunour
what is a positive of sperrys research -control
high control
ps were given eye patches and images were shown for a very brief amount of time
this makes sure that there was no possibility of ps looking over and using their other visual field
this strengthens the internal validity of the study
what are the + of sperry
support from other researchers
high control
who supports sperry ?
broca
both suggest that language is lateralised to the left hemisphere
what are the negatives of sperry ?
quasi experiment
external validity
population validity
how does sperry have poor validity?
small sample size makes it hard to generalise to other people and the task was unrealistic to real life
we dont have a stimulus presented to just one hemisphere irl
split brain procedure is rarely carried out now, meaning that patients are difficult to come by
most research has few ps and often the research takes an idiographic approach
any conclusions drawn could only be representative of those who had a physical disorder that resulted in the need for a split brain procedure
cant be generalised to wider population
quais experiemtn - sperry -ve
the group of ps are already predetermined ( split brain patients ) means its more difficult to establish cause and effect
what is the main advantage of brain lateralisation?
increases neural processing capacity (perform multiple tasks simultaneously )
rogers et al
found that in dometic chicken, brain lateralisation is associated with an enhansed ability to perform 2 tasks at once (finding food and being vigilant)
using only one hemipshere to engage in a task leaves the other one free to do other functions
this provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks
what is the weakness of rogers et al
because the research wss carried out on animals it is impossible to conclude the same of humans
what is the weakness of research into lateralisation?
split brain procedure is rarely carried out now, meaning that patients are difficult to come by
most research has few ps and often the research takes an idiographic approach
any conclusions drawn could only be representative of those who had a physical disorder that resulted in the need for a split brain procedure
cant be generalised to wider population
research suggests that lateralisation changes with age- szaflarki et al
found that langauge became more lateralised to the left hemisphere with increasing age in children and adolescents
but after the age of 25 lateralisation decreased with each decade of life
this raises questions about lateralisation such as whether everyone has a dominant hemisphere and whether this dominance changes with age
turk et als argument
it could be argued that language may not be restricted to the left hemisphere
turk et al discovered a patient who suffered damage to the left hemipshere but developed the capacity to speak in the right hemisphere
this eventually led to the ability to speak about the information presented to either side of the brain
suggests that lateralisation isnt fixed and that the brain can adapt following damage to certain areas
