Effects of psilocybin microdosing on awe and aesthetic experiences: a preregistered field and lab-based study

Van Elk and colleagues situate their study within growing public and scientific interest in psychedelics, and in particular the popular practice of microdosing, in which sub-hallucinogenic amounts of substances such as LSD or psilocybin are taken repeatedly. They note that much of the evidence for beneficial effects of microdosing comes from anecdotal reports and uncontrolled self-report surveys, and that experimental findings to date are mixed; some controlled studies report subtle effects on cognition or brain connectivity, whereas others find little or no reliable benefit. The authors identify two additional problems in the literature: low ecological validity of many laboratory measures, and the difficulty of separating true drug effects from expectancy and breaking-blind effects in placebo-controlled designs. The present study therefore aimed to test whether psilocybin microdosing increases feelings of awe and alters aesthetic experience in a preregistered, placebo-controlled, combined field-and lab-based design. Building on prior work linking full-dose psychedelic experiences and awe to similar neural signatures (for example, decreases in default mode network activity) and on associations between absorption and responsiveness to psychedelics, Van Elk and colleagues hypothesised that microdosing would increase awe to awe-inducing videos and increase perceived profoundness and positive emotions in response to abstract artworks. The study also planned to examine moderators such as the trait absorption scale and to probe potential expectancy effects.

The study used a within-subjects, double-blind crossover design embedded in a microdosing workshop. Participants who attended a microdosing information workshop organised by the Psychedelic Society of the Netherlands prepared seven capsules and then volunteered to self-administer either psilocybin-containing truffles (0.7 g dried truffle per dose, roughly equivalent to about 1.5 mg psilocybin per capsule) or a placebo capsule for three weeks on a schedule of one day on followed by two days off. After a two-week washout period the condition assignment was reversed, so each participant experienced both psilocybin and placebo blocks. Participants were instructed to take the capsule about 1.5 hours before the lab session and to follow behavioural guidelines (e.g. no other psychoactive substances); ethical approval was obtained from the University of Amsterdam. Recruitment started with 75 participants; after dropouts, non-compliance and missing data the final analysis sample comprised 30 participants for the awe task and 28 for the art perception task (17 female; mean age 29.1, range 20–48). Thirteen participants began with psilocybin first and 17 began with placebo first. The authors report that many participants had prior psychedelic experience, but quantitative data on prior use for the analysed sample were not available in the extracted text. No a priori power analysis was conducted because expected effect sizes were uncertain and recruitment depended on workshop attendance. Outcome measures were administered during four lab sessions (two per block). The primary awe manipulation used validated video stimuli: awe videos (vast natural scenes), positive videos (funny animals), and neutral/control videos (manmade objects/boring landscapes). After each video participants rated five awe-related items that were combined into an overall awe score, and completed a pictorial body-size estimation intended to capture the ‘‘small self’’ component of awe. For art perception, participants viewed abstract paintings by four artists (de Kooning, Hundertwasser, Kandinsky, Picasso) and rated perceived profoundness and positive and negative emotions; emotion items were aggregated into positive and negative scores. The full protocol and analyses were preregistered on the Open Science Framework. A repeated-measures ANOVA framework was pre-specified. For awe and body-size outcomes the within-subject factors were Condition (psilocybin vs placebo), Video (Awe, Positive, Control) and Testing Session (1st vs 2nd within-block visit). For art measures factors were Condition, Artist, and Testing Session. To correct for multiple comparisons authors set a significance threshold of p = 0.025 for the four omnibus tests and applied Bonferroni correction for post-hoc tests. The Tellegen absorption scale and measures of prior expectations were collected and included in additional covariate analyses. The authors note a deviation from the preregistration: a programming error led to incomplete counterbalancing of specific videos and paintings across sessions, meaning block-order effects are partly confounded with particular stimuli.

Awe: The video manipulation was successful, with a strong main effect of Video showing awe videos elicited greater awe than positive and control videos, F(2,58) = 94.144, p < 0.001, η2 = 0.765. There was also a main effect of Condition: participants reported more awe in the microdosing than in the placebo condition, F(1,29) = 8.309, p = 0.007, η2 = 0.223. A Condition by Session interaction was marginal, F(1,29) = 4.934, p = 0.034, η2 = 0.145, and a three-way Condition × Session × Video interaction reached p = 0.044, F(2,58) = 3.308, η2 = 0.102, but this did not survive correction for multiple comparisons. Including block order as a between-subjects factor revealed a Block Order × Condition × Video interaction, F(2,56) = 3.950, p = 0.025, and a Block Order × Condition × Session interaction, F(1,28) = 10.502, p = 0.003. Those interactions indicated that the increased awe during psilocybin was most evident in the first block and primarily affected responses to positive and neutral videos rather than the awe videos. Trait absorption had a strong main effect on awe (high-absorption participants reported more awe), F(1,28) = 18.36, p < 0.001, η2 = 0.396, but absorption did not interact with Condition (F(1,28) = 0.92, p = 0.346). Body size estimation: Contrary to expectations, there was no main effect of Video on perceived body size, F(2,58) = 0.118, p = 0.889, and no main effect of Condition, F(1,29) = 0.766, p = 0.389. A Condition × Session interaction was significant, F(1,29) = 11.382, p = 0.002, η2 = 0.022, reflecting nonsignificant tendencies for overestimation of body size in the psilocybin condition across some sessions. A Video × Condition × Block Order interaction was also observed, F(2,56) = 4.805, p = 0.012, η2 = 0.010, which unexpectedly indicated a tendency to overestimate body size under psilocybin for neutral videos in the first block. Absorption showed no significant effects on body-size estimates. Art perception: Psilocybin microdosing did not reliably alter positive aesthetic experiences, F(1,27) = 2.542, p = 0.122, nor did it affect negative aesthetic experiences, F(1,27) = 2.337, p = 0.138. Interactions between Condition and Session or Block Order were non-significant for both positive and negative ratings. Trait absorption predicted stronger positive and stronger negative aesthetic emotions: positive emotions, F(1,26) = 7.651, p = 0.010; negative emotions, F(1,26) = 7.915, p = 0.009. A main effect of painter showed differences in positive responses across artists, F(3,81) = 15.011, p < 0.001, η2 = 0.357, with Kandinsky eliciting the strongest positive feelings and de Kooning the least. Blinding and expectations: Participants broke blind at high rates. After the first block 20 of 30 participants correctly guessed their condition, χ2(2) = 10.90, p = 0.004, and after the second block 23 of 30 did so, χ2(2) = 13.93, p < 0.001. When prior expectations were included as a covariate in the awe ANOVA, the main effect of Condition disappeared (block 1 expectations: F = 0.086, p = 0.772; block 2 expectations: F = 0.266, p = 0.610). Expectations themselves predicted awe (block 1: F(1,28) = 4.80, p = 0.037, η2 = 0.146; block 2: F(1,28) = 9.210, p = 0.005, η2 = 0.248). The authors report that participants held strong expectations regarding benefits such as increased flow and creativity, and these expectations were comparable before both blocks.

Van Elk and colleagues interpret their primary finding as a modest increase in self-reported awe during psilocybin microdosing, but they emphasise important qualifications. The increased awe was strongest for positive and neutral videos (funny animals, moving objects, manmade scenes) and was most pronounced in the first block and first session, suggesting habituation or diminishing effects over repeated exposures. The authors did not find consistent effects on body-size estimation or on aesthetic responses to abstract art. A central concern raised by the researchers is that most participants correctly identified their condition, and that including pre-block expectations as a covariate abolished the Condition effect on awe. They therefore consider expectancy, misattribution of arousal, and motivated responding as plausible drivers of the observed subjective effects, and suggest that subtle physiological cues (e.g. sweating or dry mouth) may have allowed participants to infer condition. The authors also note that the awe items used were relatively generic and may have tapped valence and arousal as well as self-transcendence, which could confound interpretation. The discussion acknowledges several limitations that constrain generalisability: a strong self-selection bias because recruitment occurred via a microdosing workshop, high attrition and missing data, incomplete counterbalancing of stimuli due to a programming error, lack of psychometric validation for the specific awe items used, and the field-based nature of the workshop setting. These factors, together with the relatively high microdose (0.7 g dried truffle, at the high end of typical user reports), may have increased the likelihood of breaking blind. In terms of implications, the authors recommend that future studies include active placebos or lower doses to mitigate breaking-blind effects, use better validated measures of awe (for example the Awe Experience Scale), and pursue more controlled lab-based designs while retaining ecologically valid outcome measures. They also note that absorption is a reliable predictor of awe and aesthetic intensity, but their study was likely underpowered to test moderation of microdose effects by absorption.

The study concludes that psilocybin microdosing produced small increases in self-reported awe to certain video stimuli, but that these effects were likely influenced by participants' expectations and by frequent breaking of the blind. Van Elk and colleagues recommend that future microdosing research address expectancy and blinding more robustly (for example with active placebos), employ validated measures of awe and art experience, and use systematic lab-based protocols alongside ecologically valid tasks to clarify whether sub-perceptual doses exert genuine perceptual or affective effects.