Abstract

The Psychedelic Experience Questionnaire/Scale (PES), also known as the States of Consciousness Questionnaire, is a thematically rich questionnaire on the psychedelic experience from the 1960s. Contemporary research with the PES uses the questions that relate to mystical experience (Mystical Experience Questionnaire, MEQ), while the non-MEQ questions of this questionnaire remain largely unused in psychedelic research and therapy. We analyzed (factor and path analyses) the MEQ30 and the non-MEQ items of the PES from 140 healthy participants (239 measurements) across six studies with moderate to high doses of LSD and/or psilocybin.

The analyses revealed internally consistent extended-mystical, visual, and distressing psychedelic-experience subscales as well as meaningful interactions of distressing, visual, and mystical experiences. Some highlights of the new psychometric measurement possibilities for the psychedelic experience include: the mystical part of the psychedelic experience can be measured more comprehensively and now for instance also includes a sense of connectedness (for example to others and the world); the visual/visionary part of the psychedelic experience can be shown to often involve imagery that is felt to be of artistic quality; distressing experiences like experiencing one’s death or fearing that one might go insane can lead to mystical experiences via visually seeing a brilliant, radiant, white or golden light.

These and more of our newly established PES psychometric measurement possibilities allow for a more comprehensive measurement of the psychedelic experience for both clinical research and therapy than has hitherto been possible. Furthermore, some preliminary findings of how we use the PES with still more classic psychedelics (mescaline, DMT) and for research with patients (LSD for depression and anxiety) will also be presented. Finally, other questionnaires that also cover the psychedelic experience rather comprehensively as well as further literature will be compared with the PES. This will show what kind of future studies are needed to move toward a still more comprehensive measurement of the psychology of the psychedelic experience.