Set is a person’s psychological state and expectations; setting is the place, the people and the culture around them. Researchers in the early 1960s, including Timothy Leary and colleagues, put the idea to work in psychedelic research (Hartogsohn, 2021), and a 1963 paper by Leary, Litwin and Metzner reported reactions to psilocybin given in a supportive environment (Leary et al., 1963).
In safety research the phrase helps explain why one substance can produce very different experiences. A pooled analysis of 23 laboratory studies found dose the strongest predictor of response, with mood and personality also playing a part (Studerus et al., 2012). A 2018 prospective survey linked intentions, mindset and comfort with the setting to how experiences unfolded (Haijen et al., 2018).
Definitions are still loose. A 2025 Delphi exercise with 89 experts from 17 countries agreed reporting items for setting in clinical trials, but the experts split on whether set and setting can be studied separately (Pronovost-Morgan et al., 2025). A careful setting does not make any experience safe.
General information, not medical advice. In an emergency in Canada, call 911. For a mental-health crisis, call or text 9-8-8.
Sources
- Hartogsohn (2021), Set and setting in the Santo Daime
- Studerus et al. (2012), Prediction of psilocybin response in healthy volunteers
- Haijen et al. (2018), Predicting responses to psychedelics
- Pronovost-Morgan et al. (2025), Delphi consensus for reporting of setting
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