Ginkgo biloba is an herb that is thought to increase blood flow in the brain and enhance memory processes. In a carefully controlled study investigating this claim, young adults were assigned to one of three groups. Those in group 1 took a capsule containing 120 milligrams of ginkgo biloba once a day. Those in group 2 took a capsule that looked identical but was a fake. Those in group 3 did not take any capsules. The participants assigned to group 2 constituted the _____ in this study.
A) dependent variable
B) placebo control group
C) extraneous group
D) out-of-control group

Question

Quizplus · Accepted Answer

The participants assigned to group 2 were given a fake capsule or a placebo to control for the effects of taking a pill and any psychological or expectation-related factors that might influence the results. Therefore, the participants assigned to group 2 were the placebo control group. The dependent variable is the measure of interest in the study (e.g., memory performance), whereas the extraneous group and out-of-control group are not standard terms in experimental design.

Ginkgo Biloba Is an Herb That Is Thought to Increase