Sperry’s (1968) classic investigation into hemispheric lateralisation is classified as a quasi-experiment. Which of the following statements correctly explains why this experimental design was used, and identifies a major methodological limitation arising from this choice?
The independent variable (having a severed corpus callosum) was naturally occurring due to therapeutic necessity, which means pre-existing brain damage or long-term epilepsy could act as a major confounding variable.
The dependent variable (verbal or motor responses to stimuli) had to be measured using qualitative verbal reports, which means the findings are subjective and prone to researcher bias during transcription.
The control group (participants with intact brains) was selected after the surgical group, which means any lateralisation differences observed are likely due to age-related cognitive decline rather than the surgery.
The independent variable was manipulated in a highly artificial laboratory environment, which means the findings lack ecological validity and cannot be generalised to everyday visual tasks.
