A team of psychologists was interested in studying the effects of alcohol on peoples’ reaction times. Earlier research suggested that an increase in reaction time was either due to the alcohol itself or due to peoples’ expectations.

The psychologists recruited two groups of volunteers (an independent groups design) from a local university. Each participant’s reaction time was measured by using a computer game. The participants were then given a drink. The first group received a drink containing a large measure of strong alcohol; the second group received an identical drink without alcohol, but with a strong alcoholic smell.

Finally, all participants were required to play the computer game again to assess their reaction time. Once they had completed the task, they were then thanked for their time and allowed to leave.