Effects of varied doses of psilocybin on time interval reproduction in human subjects

Psilocybin, a hallucinogenic substance, alters the internal representation of time by increasing the loss rate of the internal duration representation. In two double-blind, placebo-controlled experiments—one with 12 subjects receiving graded doses and another with 9 subjects receiving a very low dose—participants repeatedly reproduced time intervals between 1.5 and 5 seconds. The parameter kappa from the 'dual klepsydra' model was used to assess effects. At 90 minutes after intake, psilocybin significantly increased kappa, indicating a higher loss rate of internal time representation. These findings may relate to qualitative changes in subjective time during altered states of consciousness.

Study at a glance

Abstract

Action of a hallucinogenic substance, psilocybin, on internal time representation was investigated in two double-blind, placebo-controlled studies: Experiment 1 with 12 subjects and graded doses, and Experiment 2 with 9 subjects and a very low dose. The task consisted in repeated reproductions of time intervals in the range from 1.5 to 5s. The effects were assessed by parameter kappa of the 'dual klepsydra' model of internal time representation, fitted to individual response data and intra-individually normalized with respect to initial values. The estimates kappa were in the same order of magnitude as in earlier studies. In both experiments, kappa was significantly increased by psilocybin at 90 min from the drug intake, indicating a higher loss rate of the internal duration representation. These findings are tentatively linked to qualitative alterations of subjective time in altered states of consciousness.