A Level Psychology OCR Practice Exam

What type of experiment was conducted by Sperry et al (1968)?

1. Controlled experiment

2. Quasi experiment

3. Longitudinal study

4. Field experiment

The correct answer is: Quasi experiment

The experiment conducted by Sperry et al. (1968) is classified as a quasi-experiment because it involved a comparison of individuals with and without specific characteristics—in this case, patients who had undergone a commissurotomy, which is a surgical procedure that involves cutting the corpus callosum to alleviate severe epilepsy. The research did not involve random assignment to conditions, as the participants already belonged to the group of individuals who had this specific brain surgery. In quasi-experimental designs, researchers often take advantage of pre-existing differences among groups rather than manipulating an independent variable in a controlled manner. This aligns with Sperry et al.'s work, which explored the effects of hemisphere disconnection on cognitive and perceptual tasks, allowing for a natural comparison between different brain states without the level of control found in a fully controlled experiment. Controlled experiments, longitudinal studies, and field experiments each have distinct characteristics that do not apply in this context. A controlled experiment typically involves random assignment and manipulation of variables, which was not the case here. Longitudinal studies focus on data collection over an extended period to observe changes over time, while field experiments are conducted in real-world settings, which also differs from the study's structure. Thus, categorizing Sperry