split brain research and hemispheric lateralisation ao3 Flashcards
Strength - research support
P: Sperry et al Pioneering work into the split brain phenomenon has produced impressive and sizeable body of research findings
E:The main conclusion of these appears to be that the left hemisphere is more geared towards analytical and verbal tasks whereas the right is more adept at performing spatial tasks music and other creative things.
E: The right hemisphere can only produce rudimentary words and phrases will contribute emotional and holistic content to language. Furthermore research suggests that the left hemisphere is the analyser while the right hemisphere is this synthesiser.
L: Such findings our key contributions to our understanding of brain processes and have furthered our knowledge considerably.
Weakness - issue of generalisation
P: A limitation of Sperry’s research into split brain patients is that it has been argued the findings are not generalisable.
E: This is largely down to the sample of patients that were used. Split-brain patients are such an unusual sample of people and they are rarely encountered in sufficient numbers to be useful for research.
E: There were only 11 people who took part in all variations of the basic procedure, all of whom had a history of epileptic seizures. It has also been argued that this may have influenced the findings.
Furthermore, it is also the case that some participants had experienced more disconnection of the two hemispheres than others. Finally, the control group Sperry used made up of 11 people who did not have epilepsy, may have been inappropriate. It may have been more valid if the control group had been made up of epileptics who had not had a commissurotomy, as a much more valid group would be epileptic people who had not had the operation. The epilepsy or the drugs used to treat the epilepsy may have affected the patients’ brains irrespective of the split-brain procedure and could be responsible for the results.
L: Issues such as those outlined above seriously impede the validity of the research, as it reduces the generalisability, but also the internal validity, as variables were not being controlled appropriately.
strength - highly scientific
P: one strength of split brain research and hemispheric lateralisation is how scientific it is
E: this is because sperry and gazaniga had a remarkable level of control over the procedures. this can be seen by how specialised and standardised those procedures were. for example sperry presented the infomation at 1/10th of a second so that the patient wouldnt have time to move their eye across the image and so spread the information across both sides of the visual field
E: this ensured the information went to only one of the hemispheres
L; this high level of control and standardisation allowed them to replicate the research many times as well as carrying out different variations to learn more about hemispheric lateralisation.
limitation - lack of control over extraneous variables
P; sperrys research has been critcised due to the lack of control over extraneous variables
E: for example, the amount of disconnection between the hemispheres varied between 11 ppts. whereby the extent to which the corpus callosum had been cut was greater in some patients than in others. secondly, there was a lack of a valid control group because all the split brain patients had suffered from epileptic seizures whereas the control group had no epileptic seizures. hence they were not a direct comparison. thirdly, some of the split brain patients had expirenced drug therapy to help with their epilepsy much longer than others - posing an extraneous variable affecting the brains ability
L; all of these extraneous variables undermine how much we can learn about hemispheric lateralisation from this split brain research.
