Lateralisations and split-brain research Flashcards
What is split brain research?
research that studies individuals who have been subjected to the surgical separation of the two hemisphere’s of the brain as a result of the severing of corpus callosum
what is hemispheric lateralisation?
refers to the fact that some mental processing in the brain are specialised to either the left or right hemisphere
Describe Sperry and Gazzaniger’s research (1967)
An image/word is presented in the patient’s left visual field or the right visual field
drawing tasks - presented a picture in their left or right visual field and were asked to draw what they saw
describe what they saw - a picture was presented to either the left or right visual field and participants were asked to describe what they saw
They would fixate on a dot in the centre of the screen whilst information was presented in either the left or visual field they were then asked to make responses with either their left or right hand or verbally without seeing what their hand was doing
what was the result of sperry and Gazzinger’s study
left hemisphere is responsible for speech and language and the right hemisphere is specialises with visual-spatial processing and facial recognition. Information from the left visual field is processed by the right hemisphere (no language centre and cannot respond verbally) and information from the right visual field is processed by the left hemisphere
Name an evaluation point for lateralisation
it can be related to neural capacity
because one hemisphere is used to engage in a particular task this would leave the other hemisphere to engage in another function
There is little empirical evidence to show that lateralisation confers to any advantage to the functioning of humans yet it does show this in chickens Rogers et al 2004 found that chickens showed greater neural capacity when in engaged in dual task performance such as finding food and being vigilant for predators
List studies to support lateralisation
There disadvantages associated with hemispheric lateralisation for example architects and mathematically gifted people tend to have a superior right-hemispheric skills but are likely to be left handed and suffer from more allergies and problems with the immune system
Tonnesen in 1993 found a small but significant relationship between handedness and immune system disorders suggesting that the same genetic process that leads to lateralisation may affect development in the immune system
Name a third study associated with lateralisation and split brain research
it changes with age
lateralised patterns found in younger individuals tend to switch to bilateral patterns in healthy older adults. For example Szafarlaski et al in 2006 found that language became more lateralised to the left hemisphere with increasing age in children and adults but after the age of 25 lateralisation decreased with each decade in life.
Name evidence to support split brain research
Gazzinga 1988 suggests that early discoveries from split-brain research have been disconfirmed by more recent discoveries
Damage to the left hemisphere was found to be more detrimental to language functions however, the study of JW who developed the capacity to speak out of the right hemisphere with the result that he can now speak about information presented to the left or right hemisphere Turk et al 2002 challenges certain claims
Name a study to support split brain research
limitations of split brain research
Andrews in 2001 claimed that many studies are presented with as few as three participants or even one. This means that information cannot be generalised to the majority population
Patients with confounding factors have also taken part in these experiments which are not useful for research
