What Is a "Placebo" in Experimental Research

Multiple Choice

What is a "placebo" in experimental research?

A) When an experimenter deceives subjects about the experiment’s true nature,then later tells them what it is really about
B) When subjects in a control group are treated the same as the subjects receiving the treatment
C) When subjects in the control group receive a false or empty treatment so they do not adjust their behaviour to confirm the experimenter’s hypothesis
D) When neither the subjects nor an assistant helping the experimenter know specifics about the treatment or how hypothesis is being tested
E) When an event outside the experiment’s control occurs during the experiment and affects the dependent variable