In a study of factors that might affect memory, research participants were assigned to drink either an alcoholic or a nonalcoholic beverage prior to completing a memory test. those who drank the nonalcoholic beverage were assigned to the

I believe the answer is: Control condition

Control condition refers to the group of subjects that served as a basic comparison for other subjects that receive special treatment in the experiment.
The purpose for a control condition is to make the researchers able to objectively measures how a certain condition or treatment could affect the subjects compared to normal circumtances.