Belief changes associated with psychedelic use

Psychedelic substance use has long been linked anecdotally and ethnographically to religious, spiritual, animist and other "non-physicalist" belief systems, defined here as claims that aspects of reality or consciousness are not wholly reducible to matter. Previous prospective and cross-sectional studies have documented that psilocybin and other psychedelics can induce acute mystical-type experiences and enduring increases on broad spirituality scales, and two prior studies reported increases in a unidimensional "non-physicalist beliefs" factor. However, earlier measures were limited in scope and did not capture many specific beliefs commonly associated with psychedelic experiences, such as beliefs in communication with the dead, reincarnation, telepathy, or consciousness in inanimate objects. To address this gap, Nayak and colleagues conducted a large online retrospective survey of individuals who reported a single psychedelic experience that they attributed to a belief change. The study aimed to characterise a broad range of belief changes by asking participants to rate agreement with 45 belief statements before, after, and at the time of survey administration, and to relate belief change to features of the experience (notably mystical-type experiences). Factor analysis was used to reduce dimensionality and to report change both at factor and individual-item levels, with particular attention to durability of change and associations with mystical experience ratings.

This was an anonymous, online, retrospective survey of adults (≥18 years) who self-identified as having had a belief-changing psychedelic experience and could read and write English. Participants were recruited by word of mouth, social media posts (Twitter, Facebook), newsletters, email invitations and banner ads on Erowid.com between August 2020 and July 2021. The survey was hosted on Qualtrics, took roughly 50 minutes, and provided no compensation. Johns Hopkins University School of Medicine Institutional Review Board approval is reported. Respondents were asked to answer about a single reference psychedelic experience "that you feel led to the greatest belief change," including which psychedelic was used (psilocybin mushrooms, LSD, ayahuasca, N,N-DMT, 5-MeO-DMT, mescaline-containing cacti, or other), estimated dose, concurrent psychoactive drugs, age at experience, timing relative to survey, and whether it was their first psychedelic experience. Participants completed the 30-item Mystical Experience Questionnaire (MEQ30) about that experience; a "complete mystical experience" was defined as ≥60% of the maximum score on each of the four MEQ subscales, and total MEQ score was expressed as a percentage of maximum. Belief assessment comprised 45 statements drawn from existing scales (including the Reflective Dualism subscale of the Mind-body Relationship Scale, items from a Metaphysical Beliefs Questionnaire, and items from the Revised Paranormal Belief Scale) and 17 items created for this study. Participants rated agreement at three timepoints: Before (e.g. a month before the experience), After (e.g. a month after), and Now (time of survey), on a 7-point scale from −3 (Strongly disagree) to +3 (Strongly agree). Two additional questions used categorical responses: one on overall spiritual/religious self-identification (Non-believer, Agnostic, Believer) and one asking whether the experience altered their fundamental conception of reality (Yes/No/Don't know). For dimensionality reduction, the investigators performed exploratory factor analysis (EFA) using polychoric correlations and promax (oblique) rotation on the 45 items at each timepoint, guided by scree plots, Kaiser criterion and parallel analysis. Items consistently loading (≥0.4) onto factors across all three timepoints were retained; eight items that did not load consistently were removed. A holdout sample of 500 participants was reserved for confirmatory factor analysis (CFA); model fit was assessed with Comparative Fit Index (CFI) and Root Mean Square Error of Approximation (RMSEA). Cronbach's alpha was calculated for factor reliability. Analyses of change used linear mixed models with standardized summed factor scores (reverse-scored items inverted prior to summing) as outcomes and time (Before, After, Now) as the within-subjects factor. Main predictors of interest were MEQ score and whether the reference experience was the participant's first psychedelic experience; both predictors were modelled with interactions by time. Covariates included age at experience, psychological challenge rating (an 8-point scale), sex, and race (dichotomised as white vs non-white). Random intercepts for subjects accounted for repeated measures. Effect sizes are reported as standardized β, described as covariate-adjusted analogues to Cohen's d. Similar mixed models were run for each of the 45 individual belief items. Because of the large sample, the authors conservatively defined a "meaningful" change between Before and After as both statistically significant at p < 1×10−5 and a difference of at least 10% in the proportion endorsing any agreement (Slightly agree to Strongly agree). Logistic and linear regressions were used for the categorical spiritual identification and the dichotomised question about alteration of fundamental conception of reality. Country effects were explored in models restricted to countries with ≥20 participants.

Survey flow: 16,054 visitors reached the landing page, 7,336 expressed interest, 3,487 completed the survey, and after exclusions the analytic sample comprised N=2,374. Exclusions included ineligibility for language or lack of a belief-changing psychedelic experience. The sample had a mean (SD) age of 35.1 (14.0) years at survey, was 67% male, and 43% indicated the reference experience was their first psychedelic. The reference experience occurred a mean (SD) of 8.4 (12.9) years before survey; 25% reported the experience within the past year. Nearly half (48.7%) met a priori criteria for a complete mystical experience on the MEQ. Factor structure: EFA at all three timepoints supported a five-factor solution (guided by scree plot, Kaiser criterion and parallel analysis). Eight items were removed for inconsistent loadings, and one item loaded on two factors. The five factors, each with good internal consistency (minimum Cronbach's alpha across factors/timepoints = 0.80), were labelled: Dualism (12 items), Paranormal/Spirituality (14 items), Mammal consciousness (4 items: self, other humans, non-human primates, quadrupeds), Non-mammal consciousness (5 items: plants, fungi, insects, inanimate objects and similar), and Superstition (3 items: black cats, breaking mirrors, number 13). The item "The consciousness of myself does not die with my physical body" loaded on both Dualism and Paranormal/Spirituality. CFA on the 500 holdout cases yielded acceptable fit indices at all three timepoints (Before CFI 0.904 RMSEA 0.068; After CFI 0.887 RMSEA 0.067; Now CFI 0.900 RMSEA 0.066). The first two factor scores (Dualism and Paranormal/Spirituality) were highly correlated (r = 0.82). Factor-level change: Mean factor scores increased substantially from Before to After for Dualism, Paranormal/Spirituality, Mammal consciousness and Non-mammal consciousness, with standardized effect sizes reported in the abstract (Dualism β≈0.72; Paranormal/Spirituality β≈0.90; Non-mammal consciousness β≈0.72; Mammal consciousness β≈0.74). Superstition showed negligible change (β≈−0.18). Country-specific models (restricted to countries with ≥20 subjects) found no significant country × time interactions for any factor, indicating similar patterns across the six most-represented countries (USA, Canada, UK, Australia, Germany, Sweden). Item-level change: Of the 34 items loading onto the four non-Superstition factors, all but four showed meaningful increases in the percentage endorsing any agreement from Before to After according to the pre-specified criteria (p < 1×10−5 and ≥10% absolute increase). Items with notable increases included belief in reincarnation, communication with the dead, continuance of consciousness after death, telepathy, and consciousness attributed to inanimate natural objects. The three superstition items did not meaningfully change. Among the eight items that did not consistently load on a factor, three (philosophical idealism, panpsychism, determinism) showed meaningful increases, two (faith in the scientific method, philosophical materialism) showed meaningful decreases, and three (free will, abominable snowman, Loch Ness monster) showed no meaningful change. Associations with mystical experience and other predictors: Higher MEQ scores were associated with larger before-to-after increases across factor scores and for individual items that showed meaningful change; MEQ was positively associated with reporting that the experience changed one's fundamental conception of reality (p < 1×10−10) and with shift toward identifying as a "Believer" on the spiritual/religious self-identification item (also p < 1×10−10). Identification categories changed markedly: Non-believer decreased from 35.8% Before to 13.0% After, Agnostic from 35.3% to 28.2%, and Believer increased from 28.8% to 58.8%. Durability: Differences between the After and Now timepoints did not meet the study's criteria for meaningful change for any items or factors; the majority of After-to-Now differences were small, indicating that belief changes reported after the reference experience were largely maintained at the time of survey (mean follow-up 8.4 years). Finally, 86.5% endorsed that the experience altered their fundamental conception of reality.

Nayak and colleagues interpret their findings as demonstrating that a single psychedelic experience can produce substantial, enduring increases in a range of non-physicalist beliefs, as well as increases in beliefs about consciousness, meaning and purpose. Factor analysis identified five coherent belief domains; four (Dualism, Paranormal/Spirituality, Mammal consciousness, Non-mammal consciousness) increased markedly after the reference experience, whereas Superstition did not change. The magnitude of belief change correlated with higher mystical experience ratings, and the changes were largely stable when reassessed at a long average interval (8.4 years). The investigators situate their findings relative to prior work showing psychedelic-associated increases in broad spirituality and non-physicalist beliefs, noting that the present study expands the kinds of specific beliefs examined to include items commonly reported anecdotally (e.g. communication with the dead, reincarnation, telepathy, panpsychism). They observe parallel findings in a recent prospective study (Timmermann et al.), and report that changes included increases in determinism and decreases in materialism, while belief in free will remained unchanged. Several mechanisms for directional belief change are discussed. First, the REBUS model (RElaxed Beliefs Under pSychedelics) posits that psychedelics relax high-level priors and thereby enhance learning, which could make beliefs more labile. However, the authors note that REBUS alone does not explain the consistent directional shift toward non-physicalist beliefs observed here. They propose three augmenting mechanisms: 1) context and expectancy ('set and setting') may steer belief change in particular directions; 2) unmasking of innate cognitive biases (mentalizing, dualist intuitions, teleological thinking) could favour non-physicalist interpretations when high-level priors are relaxed; and 3) experiential learning, whereby compelling, "noetic" subjective events (for example, feelings of contact with entities, experiences of deeper meaning, or perceived continuity of consciousness) function as persuasive evidence that shifts belief. The authors acknowledge important limitations. The sample was a convenience online sample, predominantly from the United States (69%), and may not represent all psychedelic users. The cross-sectional, retrospective design relies on self-report and is subject to recall and selection biases; recruiting participants via a survey explicitly framed as about "belief change" may have preferentially attracted individuals whose changes were religious/spiritual in nature. Some survey items—especially within the Paranormal/Spirituality domain—were ad hoc and unvalidated, although internal consistency and in-sample validation provide some mitigation. Finally, cultural and expectancy effects were not fully disentangled; the absence of country differences in the six most-represented Western countries is noted but interpreted cautiously given shared globalised subcultural expectations. In terms of implications, the authors highlight that contextual framing and post-experience integration may shape whether belief changes are desirable or problematic, with potential relevance for therapeutic settings. They recommend prospective studies in diverse samples, and further investigation of the neural, contextual, dispositional and experiential mechanisms underpinning psychedelic-associated belief change.

The study concludes that a single psychedelic experience can produce increases across a broad set of non-physicalist beliefs and beliefs about consciousness, meaning and purpose, and that the magnitude of these changes is associated with particular subjective features of the experience, especially mystical-type experiences. The authors call for future research to probe the roles of brain circuitry, context, innate cognitive dispositions, and experiential mechanisms in producing such belief changes.