Irving Kirsch

Irving Kirsch (born March 7, 1943) is an American psychologist, now associate director of the Program in Placebo Studies at Harvard Medical School and Beth Israel Deaconess Medical Center, and professor emeritus at the University of Hull and the University of Connecticut.

He is the originator of response expectancy theory — the proposal that what people expect to feel or experience can directly produce that very response, so that expectancy is not merely a bias in reporting but a genuine cause of physiological and emotional change.

This framework reorganized how psychology understands the placebo effect: not as “nothing happening” but as expectation generating real outcomes through ordinary, documentable pathways. Kirsch is best known publicly for his meta-analyses of antidepressant clinical trials, argued in The Emperor’s New Drugs (2009), which concluded that much of the measured benefit of common antidepressants over placebo is small and may be largely an expectancy/active-placebo effect — findings that influenced treatment-guideline debates in the UK.

He has also been a leading figure in the nonstate account of hypnosis, treating hypnotic responding as governed by expectancy, motivation, and imagination rather than a special trance state. In the Atlas he is an empirical-spine figure: he supplies the rigorous mechanism — expectancy — beneath the best-evidenced truth that belief measurably shapes outcome, while drawing the line sharply, since his work is also a debunking of overstated drug effects and mystified hypnosis.