George Fejer, MSc

University of Amsterdam

The Doors of Perceived Simultaneity: effects of microdosing psilocybin on the perception of asynchronous audiovisual speech


Microdosing psychedelics in subperceptual quantities has become an increasingly popular trend through anecdotal claims of alleged benefits such as enhanced awareness, creativity, mood and mental wellbeing (Fadiman & Korb, 2019). Although this practice denotes the absence of subjectively detectable alterations in perception and cognition, microdosing LSD has recently been shown to induce temporal dilation within the suprasecond range during a temporal reproduction task under double-blind, placebo-controlled conditions (Yanakieva et al., 2018). In a double-blind placebo-controlled study we investigated the within-subjects effects of microdoses of psychedelic truffles on basic temporal factors involved in multisensory integration of audio-visual speech. Following the procedure developed by E. Van der Burg and Goodbourn (2015), we examined whether microdosing psychedelics accutely affects rapid temporal recalibration in response to single audiovisual events and quantified the truffles’ active psychedelic alkaloids. We predicted that psychedelics would increase the temporal resolution of speech events and dilate the perceived distances between audio-visual stimulus onset asynchronies. Microdosing does not affect the point of subjective simultaneity, which was solely dependent of the previous leading modality. However microdosing increases the bandwidth of subjective synchrony judgements, thereby expanding the temporal integration window wherein audiovisual events may be perceived as synchronous.


George Fejer studied Bioscience at the university of Heidelberg and completed his Masters degree in Cognitive Neuropsychology at the Vrije University in Amsterdam with a thesis project that investigated the effects of Microdosing. He is a board member of the Amsterdam Psychedelic Research Association, whose collaboration with the Psychedelic Society of the Netherlands as well as communities made the student research project on Microdosing possible.



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