Procedure or substance with no intrinsic effect but is useful to convince the patient or subject that an effective treatment has been applied. Placebos often have effects that are attributable to suggestion. They are used extensively in medical research for control purposes during drug testing and for certain psychosomatic illnesses. In PDD it addresses one type of mental countermeasure whereby examinees use ritual objects, incantations, or other ineffectual actions with the expectation that the power of the polygraph to uncover deception will be impeded.