The effects of psilocybin on time perception in humans: A comparative analysis of subjective and objective measures

Background: Although psychedelics have regained attention as potential treatment tools for various mental disorders, little research has examined their impact on temporal perception. Aims: This double-blinded placebo-controlled study aimed to investigate changes in temporal perception under psilocybin, both through performance during the Temporal Bisection Task (TBT) and through subjective self-report scales. Methods: Twenty-four healthy volunteers were assessed by comparing their performance on two parameters of the TBT —the Bisection Point (BP) and the Just Noticeable Difference (JND) with subjectively reported changes measured using the Hallucinogen Rating Scale (HRS) and the Altered States of Consciousness (ASC) questionnaires. Results: We observed a rightward shift in BP under psilocybin compared to placebo ( t (23) = 2.27, p = 0.033, g = −0.37). This shift corresponded to reports of subjective time slowing down under psilocybin as measured by HRS and ASC. Psilocybin also increased JND compared to placebo ( t (23) = 2.48, p = 0.021, g = −0.47), indicating decreased temporal precision. Consistent with previous findings, these effects were significant for durations longer than 2 seconds. Conclusions: Based on Bayesian framework of timing, we emphasised that psilocybin alters time perception through disruptions in cognitive functions, particularly working memory and attention. We also outlined directions for future research, which would allow us to not only understand time perception under psychedelics better, but help elucidate the role of serotonergic system on timing. Research ID: The research was conducted as part of a clinical trial registered at EudraCT database under the number 2012-004579-37.