Below is a list of several research studies. Identify the type of design being used.

A study investigating whether gender plays a role in whether someone prefers reality-television or fiction-based television. (2x2 factorial design)

A study that tests two randomly assigned groups reaction time using a computer, then gives one group 100mg of caffeine, then retests both groups reaction time using a computer.

A study that tests a new drug for efficacy in fighting multiple sclerosis. Before treatment, both groups are assessed for symptom severity. Then, once treatment begins, one group receives the drug, while the other group does not; both groups are again assessed for symptom severity. In the second wave, the groups switch roles. The original treatment group does not receive the drug in this wave, while the original control group does receive the drug. Both groups are again assessed for symptom severity.