Hemispheric lateralisation and split-brain research Flashcards

Question

What did Sperry’s research show about interhemispheric communication?

Answer 1

That the corpus callosum is essential for integrating information between hemispheres.

Answer 2

Split-brain research made use of highly specialised and standardised procedures. The method of presenting visual information to one hemispheric field at a time was ingenious. Typically, participants would be asked to stare at a given point (the fixation point), whilst one eye was blindfolded. The image projected would be flashed up for 1/10 of the a second, meaning the split-brain patient would not have time to move their eye across the image and so spread the information across both sides of the visual field and consequently both hemispheres of the brain. This allowed the researchers to vary aspects of the basic procedure and ensured that only one hemisphere was receiving information at a time. Therefore, the procedure developed was very useful and well-controlled. Consequently, we can determine cause and effect from the research and so support the internal validity of the theory of hemispheric lateralisation.

Answer 3

Sperry and Gazzaniga’s work into the split-brain phenomenon has produced an impressive and sizeable body of research findings, the main conclusion of which appears to be that the left hemisphere is more geared towards analytical and verbal tasks, whilst the right is more adept at performing spatial tasks and music. The right hemisphere can only produce rudimentary words and phrases but contributes emotional and holistic content to language. This a key contribution to our understanding of brain processes.

Answer 4

The main researchers of split-brain research have urged caution in their widespread acceptance as split-brain patients constitute such an unusual sample of people. The sample size was very small as there were only 11 who took part in all variations of the basic procedure, all of whom had a history of epileptic seizures. It has been argued that this may have caused unique changes in the brain that may have influenced the findings. It is also the case that some participants had experienced more disconnection of the two hemispheres as part of their surgical procedure than others, and some patients had experienced drug therapy for much longer than others. The control group may have been inappropriate because they were people who had no history of epileptic seizures. Finally, the data was artificially produced as in real life, a severed corpus callosum can be compensated for by the unrestricted use of two eyes. This suggests that the research cannot be considered to be completely valid either internally or externally, and so we cannot confidently support the theory of hemispheric lateralisation from the split-brain research.

Answer 5

Pop-psychological literature overemphasises and oversimplifies the functional distinction between the hemispheres on the basis of split-brain research. Modern neuroscientists would contend the actual distinction is less clear-cut and much messier than the basic ‘verbal’ –‘non-verbal’ distinction. In the normal brain, the two hemispheres are in constant communication when performing everyday tasks, and many of the behaviours typically associated with one hemisphere can be effectively performed by the other when the situation requires it. Therefore, hemispheric lateralisation may be more complex than originally stated and the brain may work more holistically. (The split-brain research doesn’t help to dispel this oversimplification of ‘are you a left- or right-brained person?’)

Hemispheric lateralisation and split-brain research Flashcards

(29 cards)