A Placebo is a substance or treatment with no active therapeutic effect. A Placebo may be given to a person in order to deceive the recipient into thinking that it is an active treatment.

This phenomenon, in which the recipient perceives an improvement in condition due to personal expectations, rather than the treatment itself, is known as the Placebo Effect.

The Placebo Effect is related to the perceptions and expectations of the patient; if the substance is viewed as helpful, it can heal.

Placebo Effects are produced by the self-fulfilling effects of response expectancies, in which the belief that one will feel different leads a person to actually feel different.