A 30-item version of the Mystical Experience Questionnaire (MEQ) reliably measures four core dimensions of mystical experiences brought on by psilocybin: unity, noetic quality, and sacredness; positive mood; transcendence of time and space; and ineffability. Over 1,600 participants who had taken psilocybin completed the original 43-item MEQ, and factor analysis retained 30 items with a clear four-factor structure. Those who reported having a mystical experience scored significantly higher on all factors, confirming the scale's construct validity. The factor structure held in a second sample of 440 people and fit better than alternative models, supporting the MEQ's use in scientific studies of hallucinogen-occasioned mysticism.
A questionnaire was developed and validated to measure challenging psychological reactions to the hallucinogen psilocybin, often called 'bad trips.' Seven factors emerged: grief, fear, death, insanity, isolation, physical distress, and paranoia. These factors were linked to how difficult, meaningful, spiritually significant, and impactful on well-being participants rated their experiences. The factor structure was consistent regardless of gender or prior struggles with anxiety or depression. The questionnaire offers a tool for studying predictors and outcomes of such challenging experiences.