title: Concept of true and perceived placebo effects.
abstract: We often and wrongly equate the response seen in the placebo arm of a clinical trial with the placebo effect. In order to obtain the true placebo effect, other non-specific effects can be identified by including an untreated control group in clinical trials. A review of the literature shows that most authors confuse the perceived placebo effect with the true placebo effect. The true placebo effect is highly variable, depending on several factors that are not fully understood. A distinction between the perceived and the true placebo effects would be helpful in understanding the complex phenomena involved in a placebo response.
authors.affiliation: Centre for Complementary Health Studies, Postgraduate Medical School, University of Exeter.
authors.forename: E
authors.initials: E
authors.lastname: Ernst
authors.forename: K L
authors.initials: KL
authors.lastname: Resch
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D015990:Placebo Effect; D016032:Randomized Controlled Trials as Topic; D013223:Statistics as Topic