Discuss split brain research. Refer to examples of such research in your
answer. (16marks)
Hemispheric Lateralisation refers to the fact that the two halves (hemispheres) of the brain
are not identical and that certain mental processes and behaviour are controlled by one
hemisphere and not both. For example, research has found that speech and language is
localised/controlled in the left hemisphere and the right is dominate for visual and motor
tasks. The two hemispheres are connected through nerve fibres called the corpus callosum.
Sperry and Gazzaniga (1967) were the first to investigate hemispheric lateralisation with the
use of split brain patients. They used 11 individuals part of their research all who had
commissurotomy, which is a procedure where the corpus callosum which connects the two
hemispheres is separated meaning their hemispheres did not communicate. Patients were
presented with images that would be projected either to their right or left visual field. Many
different experiments were used such as describe what you see task, tactile task and
drawing task, patients had to respond either with their left hand (right hemisphere) or right
(left hemisphere) or verbally.
Results from the research found patients could say what they saw in their right visual field
but not in their left as the left hemisphere is responsible for language and right hemisphere
is not. However, the patients could draw this image with their left hand as the task did not
require language. Sperry concluded that the left hemisphere is dominant for speech and
language, while the right hemisphere specialises for visual, spatial motor tasks.
A strength of brain lateralisation is that it increases neural capacity (ability to multitask).
Supporting evidence for lateralisation comes from Rogers et al (2004) who studied chicken.
He found that brain lateralisation is linked with an enhanced ability to perform two tasks
simultaneously (finding food but also remaining alert for predators). This is as using only one
hemisphere leaves the other hemisphere free to engage in other tasks. Thus this study
provides evidence of the advantages of brain lateralization and shows how it can improve
brain efficiency in cognitive tasks. However a limitation of animal studies is that you are
unable to generalise finding to humans as chicken and humans are biologically different.
A strength of split brain research is that they are done using highly specialised and
standardized procedures. For example Sperry investigated one hemispheric field by
presenting visual information to one hemispheric field at a time. A image would be flashed
for 1/10th of a second, so patients wouldn’t have time to move their eye across the image
and so spread information in both sides of the visual field. This allowed Sperry to change
aspects of this procedure and ensure that only one hemisphere was receiving information at
a time. Therefore Sperry developed a well-controlled procedure, that was useful as he could
replicate the procedure numerous time due to the standardized procedure to check for
reliability.
A limitation of split brain research is that case studies show language may not be restricted
to the left hemisphere. For example Turk et al. (2002) discovered a patient J.W who
suffered from damage to the left hemisphere but was able to speak from the right
answer. (16marks)
Hemispheric Lateralisation refers to the fact that the two halves (hemispheres) of the brain
are not identical and that certain mental processes and behaviour are controlled by one
hemisphere and not both. For example, research has found that speech and language is
localised/controlled in the left hemisphere and the right is dominate for visual and motor
tasks. The two hemispheres are connected through nerve fibres called the corpus callosum.
Sperry and Gazzaniga (1967) were the first to investigate hemispheric lateralisation with the
use of split brain patients. They used 11 individuals part of their research all who had
commissurotomy, which is a procedure where the corpus callosum which connects the two
hemispheres is separated meaning their hemispheres did not communicate. Patients were
presented with images that would be projected either to their right or left visual field. Many
different experiments were used such as describe what you see task, tactile task and
drawing task, patients had to respond either with their left hand (right hemisphere) or right
(left hemisphere) or verbally.
Results from the research found patients could say what they saw in their right visual field
but not in their left as the left hemisphere is responsible for language and right hemisphere
is not. However, the patients could draw this image with their left hand as the task did not
require language. Sperry concluded that the left hemisphere is dominant for speech and
language, while the right hemisphere specialises for visual, spatial motor tasks.
A strength of brain lateralisation is that it increases neural capacity (ability to multitask).
Supporting evidence for lateralisation comes from Rogers et al (2004) who studied chicken.
He found that brain lateralisation is linked with an enhanced ability to perform two tasks
simultaneously (finding food but also remaining alert for predators). This is as using only one
hemisphere leaves the other hemisphere free to engage in other tasks. Thus this study
provides evidence of the advantages of brain lateralization and shows how it can improve
brain efficiency in cognitive tasks. However a limitation of animal studies is that you are
unable to generalise finding to humans as chicken and humans are biologically different.
A strength of split brain research is that they are done using highly specialised and
standardized procedures. For example Sperry investigated one hemispheric field by
presenting visual information to one hemispheric field at a time. A image would be flashed
for 1/10th of a second, so patients wouldn’t have time to move their eye across the image
and so spread information in both sides of the visual field. This allowed Sperry to change
aspects of this procedure and ensure that only one hemisphere was receiving information at
a time. Therefore Sperry developed a well-controlled procedure, that was useful as he could
replicate the procedure numerous time due to the standardized procedure to check for
reliability.
A limitation of split brain research is that case studies show language may not be restricted
to the left hemisphere. For example Turk et al. (2002) discovered a patient J.W who
suffered from damage to the left hemisphere but was able to speak from the right
