Question

A motivational speaker claims that wearing red on the day of an exam “energizes” the brain and improves performance. Your psychology professor doubts that this is true. Design an experiment that would test whether the speaker is correct.

Answer 1

A true experiment has two major features: random assignment of participants, and experimental and control groups. The research question of the study is whether wearing red on the day of an examination improves performance by energizing the brain. The hypothesis of no difference is that there is no significant difference in marks scored on an examination based on whether a student wears red on the day of the examination.

So, let's assume we conduct this experiment in a class of 100 students. We randomly allocate students in two groups of 50 each. Random assignment is important because it cancels out the result of confounding variables such as gender, IQ, motivation etc. to a considerable extent. These confounding variables cannot be taken care of as well when we employ non-random methods of sampling, such as purposive sampling or snowball sampling. Moreover, random sampling is the best for determining cause-and-effect relationships, which is what we are trying to investigate.

Now, one of the two groups will become the experimental group, i.e., the group that is exposed to the intervention or special condition, whom we will tell that they are supposed to wear "red" on the day of an upcoming examination. The other group becomes the control group, i.e., the group that is not exposed to the intervention or special condition, whom we will tell that they can wear anything but red on the day of that upcoming examination. Once the examination is over, we can determine an answer for our research question by comparing the marks of the students in the two groups, and determining, via a t-test, whether there is a significant difference in the mean scores of the two groups.

In case the experimental group scores significantly higher than the control group, or vice versa, our hypothesis will be disproven. In case there is no significant difference between the scores of the two groups, our hypothesis will be proven.