split brain research evaluation

Question 1

what were the findings of the split-brain research

Answer 1

the main conclusions:
the left hemisphere is more geared towards analysing and verbal tasks whilst the right is more adept at performing spatial tasks and music. It also produces rudimentary words and phrases but contributes emotional and holistic content to language

research suggests that the left hemisphere is the analyser while the right is the synthesiser - a key contribution to our understanding of the brain process

Question 2

what are the issues with generalisation

Answer 2

as fascinating findings from these studies are, many researchers have urged caution in their widespread acceptance,as split - brian patients constitute such an unusual sample of people

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 brian that may have influenced the findings

It also the case that some participants had experienced more disconnection of the two hemispheres as part of their surgical procedure than others

Finally, the control group Sperry used, made up of 11 people with no history of elipipesy may have been inappropriate

Question 3

what is the strength of the methodology

Answer 3

experiments involving split-brain patients made use of highly specialised and standardised procedure

Sperry’s method of presenting visual info to one hemisphere field at a time was quite ingenious

Typically, participants would be asked to stare at a given point, the fix action point

The image projected would be flashed up for one-tenth of a second meaning the split-brain patient would not have time to move their eye across both sides of the visual field, and subsequently, both sides of the brain

This allowed Sperry to vary aspects of the basic procedure and ensured that only one hemispheric was receiving info at a time
Thus he developed a very useful and well-controlled procedure

Question 4

what does it mean when we say that there are differences in functioning that may be overstated

Answer 4

one unfortunate legacy of Sperry’s work is a growing body of pop- psychological literature that overemphasises and oversimplifies the functional distinction between the left and right hemispheres

although the “verbal” and “non - verbal” labels can, on occasion be usefully applied to summarise the differences between the two hemispheres, modern neuroscientists would contend that the actual distinction is less clear - cut and two hemispheres are in constant communication when performing everyday tasks and many of the behaviours typically associated with one hemisphere can be effecting performed by the situation requires it

Question 5

lateralisation in the connected brain evidence

Answer 5

one limitation for lateralisation is that the idea of the LH as the analyser and the RH as the synthesiser may be wrong

There may be different functions in the RH and LH but research suggests people do not have a dominant side of their brain which creates a different personality

Jared Nielsen et al (2013) analysed brain scans from over 1000 people aged 7 to 29 years and did find that people used specific hemispheres for certain tasks (evidence for lateralisation). But there was no evidence of a dominant side e.g. no artist’s brain or mathematician’s brain
This suggests that the notion of right brain and left brain people are wrong

Question 6

some concepts may be wrong

Answer 6

One strength its research shows that even in connected brains the two hemispheres process information differently

For example. Fink et al (1996) used PET scans to identify which brain areas were active during the visual processing task
When participants with connected brains were asked to attend global elements of an image (such as looking at a picture of a whole forest) regions of the RH were much more active
When required to focus on the finer details (such as individual tree the specific areas of the LH tended to dominate
This suggests, at least as far as visual processing is concerned, hemispheric lateralisation is a feature of the connected brain as well as the split-brain

Question 7

research support for Sperry’s research

Answer 7

One strength is support from more recent split-brain research

Michael Gazzinga showed that split-brain participants actually performed better than connected controls on specific tasks

For example, they were faster at identifying the odd one in an array of similar objects. This is because the LH’s cognitive strategies are watered down by the inferior RH in the normal brain

This supports Sperry’s earlier findings that the “left brain” and the “right-brain” is distinct