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Tripping on nothing: placebo psychedelics and contextual factors

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Is it possible to have a psychedelic experience from a placebo alone? Most psychedelic studies find few effects in the placebo control group, yet these effects may have been obscured by the study design, setting, or analysis decisions.


We examined individual variation in placebo effects in a naturalistic environment resembling a typical psychedelic party.


Thirty-three students completed a single-arm study ostensibly examining how a psychedelic drug affects creativity. The 4-h study took place in a group setting with music, paintings, coloured lights, and visual projections. Participants consumed a placebo that we described as a drug resembling psilocybin, which is found in psychedelic mushrooms. To boost expectations, confederates subtly acted out the stated effects of the drug and participants were led to believe that there was no placebo control group. The participants later completed the 5-Dimensional Altered States of Consciousness Rating Scale, which measures changes in conscious experience.


There was considerable individual variation in the placebo effects; many participants reported no changes while others showed effects with magnitudes typically associated with moderate or high doses of psilocybin. In addition, the majority (61%) of participants verbally reported some effect of the drug. Several stated that they saw the paintings on the walls “move” or “reshape” themselves, others felt “heavy… as if gravity [had] a stronger hold”, and one had a “come down” before another “wave” hit her.


Understanding how context and expectations promote psychedelic-like effects, even without the drug, will help researchers to isolate drug effects and clinicians to maximise their therapeutic potential.

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  1. The sheet resembled Health Canada’s “Quality Overall Summary — Chemical Entities (Clinical Trial Applications — Phase III)” form containing sensible-looking but bogus information.

  2. See

  3. Square brackets throughout denote bootstrapped 95% confidence intervals.


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We would like to thank Derek Albert for DJing; research assistants Despina Artenie, Denis Chmoulevitch, Frédérik Crépeau-Hubert, Mariève Cyr, Kylar D’Aigle, Victoria De Braga, Erika Gentile, Ceren Kaypak, Kyle Greenway, Alice Leclercq, Johnny Nahas, and Dasha Sandra for help with data collection; artist Sznajberg from L’espace Entre for the paintings; Robin Carhart-Harris and the Psychedelic Research Group at Imperial College London for feedback; the Faculty of Medicine WELL Office for the bean bags; the security guards at the Montreal Neurological Institute; and seven psychonaut confederates for playing along.

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Correspondence to Jay A. Olson.

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Olson, J.A., Suissa-Rocheleau, L., Lifshitz, M. et al. Tripping on nothing: placebo psychedelics and contextual factors. Psychopharmacology 237, 1371–1382 (2020).

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