Hemispheric Lateralisation and Split Brain Research

• A strength of split-brain research into hemispheric lateralisation is Sperry's high use of standardised procedures.
• For example, an image was flashed up for 0.1 seconds, so the patient had no time to move their eyes over the image and spread the information across both sides of the visual field/brain.
• This allowed Sperry to vary aspects of the basic procedure and ensure only one hemisphere received information at a time.
• This strengthens both the reliability and support for split-brain research into hemispheric lateralisation given that the procedure can be easily replicated and all patients are treated the same.
• A limitation of split-brain research into hemispheric lateralisation is issues with generalisation in relation to Sperry's work.
• For example, the sample used was unusual and limited to epileptic patients who had undergone a commisurotomy.
• Only 11 patients took part in all variations and all had a history of seizures, which may have caused unique changes in the brain that influenced the findings.
• This weakens both the population validity and support for split-brain research into hemispheric lateralisation as we are unable to conclude that non-epileptic patients would respond in the same manner.
• Another limitation of split-brain research into hemispheric lateralisation is that differences in hemispheric functions may be overstated.
• For example, a legacy of Sperry's work is a growing body of pop-psychological literature that oversimplifies and overstates the difference in function between the two hemispheres.
• Modern neuroscientists argue these distinctions are not clear-cut, and many behaviors typically associated with one hemisphere can be performed by the other when situations require.
• This weakens both the internal validity and support for split-brain research into hemispheric lateralisation as the apparent flexibility of the two hemispheres suggests some of the conclusions drawn by Sperry may be too simplistic.