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Placebo psychotherapy: synonym or oxymoron?

Irving Kirsch¹

¹Faculty of Health and Social Work, University of Plymouth, UK. irving.kirsch@plymouth.ac.uk

Journal of Clinical Psychology

|April 14, 2005

Summary

The placebo effect is a genuine and significant phenomenon, often driven by patient expectancy. While conditioning can play a role, expectancy is key, even in cases unrelated to conditioning history.

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Area of Science:

Psychology
Neuroscience
Medical Research

Background:

Recent claims have questioned the validity of the placebo effect.
The placebo effect is recognized as a real and substantial phenomenon.
Classical conditioning and expectancy are known mechanisms influencing placebo responses.

Purpose of the Study:

To clarify the mechanisms and reality of the placebo effect.
To examine the role of expectancy in placebo responses.
To critique the application of placebo-controlled trial logic to psychotherapy.

Main Methods:

Review of contemporary conditioning theories.
Analysis of expectancy-mediated effects.
Conceptual analysis of psychotherapy research methodology.

Main Results:

Placebo effects are real and can be substantial.
Expectancy is a primary mediator of placebo effects, sometimes independent of conditioning.
Classical conditioning can produce or enhance placebo effects.

Conclusions:

The placebo effect is a valid and significant aspect of medical and psychological treatment.
Expectancy is a crucial factor in placebo responses, often overriding conditioning.
The direct application of placebo-controlled trial methodology to psychotherapy is conceptually flawed and should be reconsidered.

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