Psychedelic Experiences Increase Mind Perception but do not Change Atheist-Believer Status: A Prospective Longitudinal Study

Psilocybin and other classical psychedelics have longstanding associations with spiritual and religious practices, and recent empirical work has suggested they may sometimes shift beliefs or belief-like states. Prior studies have reported increases after psychedelic use in constructs such as mind perception (the attribution of experience or agency to various entities), non-naturalistic or metaphysical beliefs (for example, dualism or idealism), and self-reported religious identification (Atheist-Believer status). However, much of that evidence comes from cross-sectional or retrospective surveys that are vulnerable to selection and recall biases, and some controlled trials lacked effective blinding or did not focus directly on belief change as a primary outcome. Nayak and colleagues set out to examine belief-related changes prospectively in a large sample of people who planned naturalistic psilocybin experiences. The study aimed to measure changes over time in three domains: mind perception toward a range of living and non-living targets, several metaphysical belief items (materialism, dualism, idealism, determinism), and self-classified Atheist-Believer status. The investigators hypothesised increases in mind perception, shifts toward non-naturalistic metaphysical beliefs, and movement from “nonbeliever” toward “believer.” The prospective design and multiple follow-up timepoints were intended to reduce recall bias and better characterise the magnitude and persistence of any changes occurring after naturalistic psilocybin use.

This was a prospective longitudinal survey of adults (18+) who reported planning to use psilocybin in a naturalistic, non-laboratory setting. Recruitment occurred online via paid social media advertising and word-of-mouth; the recruitment materials framed the study as an investigation of variables such as demographics, mindset, dosage, and setting and did not mention belief change. An institutional review board at Johns Hopkins approved procedures and all participants provided informed consent. Participants completed questionnaires before and after their planned psilocybin session. Measures relevant to this paper were added to the ongoing study at different times, producing varying sample sizes for each domain. Atheist-Believer status was assessed at consent (baseline, N = 7,989 at consent) and again 2–3 months after the session (final analytic N = 657). Metaphysical belief items were collected at baseline, 2–4 weeks, and 2–3 months (analytic N = 623). Mind perception items were added later and were collected 2 weeks before the session, 2–4 weeks after, and 2–3 months after (analytic N = 255). Analyses were restricted to participants who provided both baseline and relevant follow-up data for each measure. Mind perception comprised ten items asking participants to rate the capacity for conscious experience of targets (four mammals, five non-mammal entities, and the universe) on a seven-point Likert scale from −3 to +3; Cronbach’s alpha = 0.87. The metaphysical battery included four items addressing materialism, dualism, idealism and determinism on the same −3 to +3 scale; Cronbach’s alpha = 0.3, indicating poor internal consistency. A single-item Atheist-Believer measure asked participants to classify themselves as Non-believer (scored −1), Agnostic (0), or Believer (1). Primary analyses used separate linear mixed-effects models for each item (15 total tests across the three domains). Outcomes were Z-scored so that standardized beta coefficients (βstd) could be interpreted akin to covariate-adjusted Cohen’s d. Models included time, Mystical Experience Questionnaire (MEQ) score, the interaction of MEQ and time, and indicators for first-time psychedelic use and ceremonial setting. Results were Bonferroni-corrected for 15 tests (alpha = .003333). Exploratory subgroup analyses examined psychedelic-naïve participants and those without a mood disorder; these were not corrected for multiple comparisons.

The analytic sample varied by outcome: Atheist-Believer status N = 657, metaphysical beliefs N = 623, and mind perception N = 255 (all participants had data at the relevant timepoints). The sample was majority male (57–60%), predominantly White (86–88%), mostly US-resident (72–86%), and included elevated rates of self-reported current mood disorder (26–31%). Thirteen to fourteen per cent reported this as their first psychedelic experience; 2–4% reported ceremonial use. Mean MEQ scores were 0.5 (SD 0.3). The MEQ score did not predict greater belief change in the primary tests. Mind perception: Participants increased their attribution of conscious experience to a range of non-human targets from baseline to both follow-ups. Items already near ceiling (self and other humans) showed little change. Significant small-to-moderate increases (βstd ≈ 0.15–0.28) were observed at both follow-ups for non-human primates, quadrupeds, insects, fungi, plants, and inanimate man-made objects. The largest effects were for insects (βstd = 0.28 [95% CI 0.18, 0.39] at 2–4 weeks; βstd = 0.35 [0.24, 0.45] at 2–3 months). Changes from the first to the final follow-up were generally small. Some inanimate natural targets (e.g., rock), a robot, and the universe showed small, significant change at one follow-up but not the other. Exploratory analyses indicated larger effect sizes for mind-perception change among psychedelic-naïve participants. Metaphysical beliefs: Overall there was little to no change in the four-item metaphysical set. Materialism, dualism, and idealism showed no significant shifts over time (βstd ranged approximately from −0.06 to 0.03). Determinism showed a small but statistically significant increase at 2–3 months (βstd = 0.12 [95% CI 0.06, 0.19]). In the psychedelic-naïve subgroup, materialism appeared to decrease more at 2–3 months (βstd ≈ −0.27, p = .001) in exploratory analyses. Atheist-Believer status: No meaningful change was detected in religious/spiritual self-identification. At baseline 24% identified as non-believer and 46% as believer, versus 25% and 47% respectively at 2–3 months. Among psychedelic-naïve participants there was likewise no clear change (26% to 28% non-believer; 33% to 34% believer). A reported subgroup effect showed decreases toward atheism in psychedelic-naïve participants (βstd reported as 0.22 with 95% CI spanning −0.43 to −0.02, p = .035), but this was exploratory and not corrected for multiple comparisons. First-time use was associated with a medium-sized increase for the single item “The universe is conscious” (βstd = 0.68 [0.36, 1.01], p < .0033).

Nayak and colleagues interpret their findings as showing a clear divergence across belief domains: naturalistic psilocybin experiences were associated with increased mind perception but produced little or no average change in metaphysical beliefs or self-classified Atheist-Believer status. Replicating prior work, the team observed increased attributions of consciousness to various non-human entities (notably insects, fungi, and plants), with larger changes among participants who were psychedelic-naïve. The authors note that their mind-perception measure probed attribution of conscious experience broadly rather than separating experience from agency, and they caution that increased perception of mind could have a range of downstream consequences—potentially beneficial (increased social-like connection), pathological (relations to conspiratorial or delusional attributions of agency), or mixed. Regarding metaphysical beliefs, the study found little evidence for a shift toward non-naturalism at the group level. The lone exception was a small increase in determinism at 2–3 months and an exploratory decrease in materialism among psychedelic-naïve participants. The investigators argue these results contrast with some prior retrospective and ceremonial-setting studies and suggest that those earlier findings may have been inflated by selection and recall biases, contextual factors (for example, ceremonial framing), or may require particular individual predispositions or repeated exposures to emerge. On Atheist-Believer status, the prospective design failed to replicate large shifts reported in retrospective surveys: overall religious self-identification remained essentially unchanged. The authors assert this outcome reduces, though does not eliminate, the urgency of ethical concerns about psychedelics causing widespread conversion or large-scale changes in religious affiliation in typical naturalistic use. They nevertheless emphasise that their null findings do not rule out sizeable belief changes in specific contexts or subgroups and do not obviate the need for informed consent and safeguards against undue influence. The paper acknowledges key limitations: the belief measures lack comprehensive psychometric validation (the metaphysical scale showed poor internal consistency, alpha = 0.3), there was no non-psychedelic control group, and the sample was heavily weighted toward experienced psychedelic users which could attenuate observed change. The authors recommend incorporating validated belief measures into randomized controlled trials and further research to establish when, for whom, and under what conditions psychedelic experiences alter different belief domains. They caution that these results should not be used to downplay ethical safeguards around potential belief changes, even while suggesting that some prior estimates of widespread conversion effects may be overstated.

In this prospective longitudinal survey of naturalistic psilocybin experiences, participants showed reliable increases in attributions of conscious experience to a range of non-human targets but little to no average change in metaphysical belief items or self-classified Atheist-Believer status. The authors conclude that psychedelics may meaningfully affect constructs related to mind perception and mentalization, while widespread shifts in metaphysical worldview or religious identification appear less common in naturalistic use. They call for further validated measurement, controlled trials, and continued ethical vigilance despite these largely null findings for metaphysical and religious affiliation changes.