Lateralisation and split-brain research 16 marker
Hemispheric lateralisation suggests that each hemisphere has different functions and each
half communicates via the corpus callosum. In addition, the left visual field and left side of
the body are processed by the right hemisphere and, the right visual field and right side of
the body are processed by the left hemisphere.
Sperry and Gazzaniga 1967 conducted research on patients with severe epilepsy who had
had their corpus callosum cut, preventing communication between hemispheres allowing
isolation of the functions of each hemisphere. They found that patients can verbalise
pictures in the right-hand field as the information is processed in the left hemisphere which
controls speech. However, if an image is displayed in the left visual field, they cannot
verbalise it as its processed by the right hemisphere which contains dominant motor
function not speech centres, but they can draw the image (motor functioning). Suggesting
that each hemisphere has different functions.
One limitation of research conducted by Sperry and Gazzaniga in support of lateralisation is
that they use very small sample sizes. Andrewes 2001 suggested that sample sizes of 11
failed to prove concrete evidence for the separate roles of hemispheres and that this loss of
function in one visual field may be due to epilepsy or a confounding disorder not the lack of
the corpus callosum. Which means a lack of population validity as there’s no proof the
findings are due to the cut of the corpus callosum and it may be the case that epilepsy or
drugs treating it could cause this lateralisation, so the research can’t be generalised to
everyone else.
Not only this but all of the patients were right-handed and male. This means that it can’t be
generalised to people who are left-handed or female because the lateralisation may just
occur in men or right-handed people. Decreasing the population validity of research
conducted by Sperry and Gazzaniga and providing poor support for hemispheric
lateralisation.
However, one positive of research into hemispheric lateralisation is that it has practical
applications by treating speech issues after strokes. This is because if a speech difficulty is
occurring then the left hemisphere (containing the speech centre) could be electrically
stimulated to boost activity. This improves stroke patient’s quality of life which increases
validity of lateralisation, as if the left hemisphere didn’t contain the speech centre then this
wouldn’t have caused an improvement of speech after a stroke.
Hemispheric lateralisation suggests that each hemisphere has different functions and each
half communicates via the corpus callosum. In addition, the left visual field and left side of
the body are processed by the right hemisphere and, the right visual field and right side of
the body are processed by the left hemisphere.
Sperry and Gazzaniga 1967 conducted research on patients with severe epilepsy who had
had their corpus callosum cut, preventing communication between hemispheres allowing
isolation of the functions of each hemisphere. They found that patients can verbalise
pictures in the right-hand field as the information is processed in the left hemisphere which
controls speech. However, if an image is displayed in the left visual field, they cannot
verbalise it as its processed by the right hemisphere which contains dominant motor
function not speech centres, but they can draw the image (motor functioning). Suggesting
that each hemisphere has different functions.
One limitation of research conducted by Sperry and Gazzaniga in support of lateralisation is
that they use very small sample sizes. Andrewes 2001 suggested that sample sizes of 11
failed to prove concrete evidence for the separate roles of hemispheres and that this loss of
function in one visual field may be due to epilepsy or a confounding disorder not the lack of
the corpus callosum. Which means a lack of population validity as there’s no proof the
findings are due to the cut of the corpus callosum and it may be the case that epilepsy or
drugs treating it could cause this lateralisation, so the research can’t be generalised to
everyone else.
Not only this but all of the patients were right-handed and male. This means that it can’t be
generalised to people who are left-handed or female because the lateralisation may just
occur in men or right-handed people. Decreasing the population validity of research
conducted by Sperry and Gazzaniga and providing poor support for hemispheric
lateralisation.
However, one positive of research into hemispheric lateralisation is that it has practical
applications by treating speech issues after strokes. This is because if a speech difficulty is
occurring then the left hemisphere (containing the speech centre) could be electrically
stimulated to boost activity. This improves stroke patient’s quality of life which increases
validity of lateralisation, as if the left hemisphere didn’t contain the speech centre then this
wouldn’t have caused an improvement of speech after a stroke.
