Four participants sign up for an experiment examining the effects of alcohol on sociability. One participant is given an alcoholic beverage to drink and is told that it is alcohol. A second participant is given an alcoholic beverage to drink but is told that it is nonalcoholic. A third participant drinks a nonalcoholic beverage but is told that it contains alcohol, and a fourth participant is given a nonalcoholic beverage and is told that it is nonalcoholic. This illustrates a _____ placebo design.