In work recently published in the Journal of Psychopharmacology, scientists have breathed new life into a decades-old tool for understanding the psychedelic experience, expanding our grasp of these profound states of mind. By reviving and updating the Psychedelic Experience Scale, researchers can better explore the subjective effects of psychedelic substances, paving the way for new understandings of consciousness and opening the door to innovative approaches for treating mental health conditions.
Psychedelic substances, such as LSD and psilocybin (found in magic mushrooms), have fascinated both scientists and the public for decades. Initially explored in the 1950s and 1960s for their potential in psychiatric treatment and understanding of the human mind, these substances prompted the development of tools to measure their effects on consciousness. However, legal and societal pushbacks during the late 20th century put a damper on this research.
Recently, there’s been a renaissance in the scientific community’s interest in psychedelics, driven by promising results in treating conditions like depression, anxiety, and post-traumatic stress disorder. This modern revival has necessitated better tools to quantify and understand the complex and multifaceted experiences these substances evoke.
“Studying the psychology of the psychedelic experience is a worthwhile endeavor. As studies have shown, such an experience is often deeply meaningful, and is also often associated with enduring positive effects on attitudes, mood, and behavior in healthy individuals and — in conjunction with psychotherapy — with sustained symptom reductions in individuals suffering from depression, anxiety, and addiction,” explained study author Kurt Stocker, a research associate in psychopharmacology at University Hospital Basel and project leader for consciousness studies at ETH Zurich.
“Seeing such potential benefits of the psychedelic experience, it becomes clear that it might be helpful if we could psychometrically capture the important aspects of this experience as comprehensively and concisely as possible. The better we can capture the psychedelic experience, the better we might be able find out what the actual beneficial aspects of it are.”
Enter the Psychedelic Experience Scale (PES), originally developed by Walter Pahnke and William Richards in the 1960s and 1970s. This tool aimed to comprehensively measure the psychedelic experience, covering aspects from mystical revelations to visual phenomena and emotional challenges.
Modern researchers have employed the Mystical Experience Questionnaire (MEQ), which was derived from the PES, to assess subjective effects of psychedelic substances. But while mystical experiences are a significant and well-documented aspect, they do not account for the entirety of the psychedelic experience. By exploring the psychometric properties of the PES, the researchers aimed to uncover additional dimensions of the psychedelic experience that could be systematically measured and studied.
“The Psychedelic Experience Scale (PES) — with the analytical approaches developed in our paper — is a useful psychometric instrument for this,” Stocker told PsyPost. “Its experiential spectrum covers mystical, visual, and challenging/distressing psychedelic experiences with a conceptual breadth and depth that remains unmatched when it comes to capturing such an experience as comprehensively and concisely as possible within a single questionnaire.”
Using data from 140 healthy participants, who contributed a total of 239 PES measurements from six different studies on classic psychedelics, the researchers successfully identified and validated four new subscales within the PES: paradoxicality, connectedness, visual experience, and distressing experience.
The paradoxicality subscale emerged from the analysis as a reflection of the psychedelic-induced awareness that seemingly contradictory principles can both be true. This dimension captures experiences where conventional logic fails, and the individual confronts the limits of rational thought, diving into a realm where opposites coexist. Items within this subscale relate to experiences of identity loss, the dissolution of temporal boundaries, and the merging of self with the environment.
Connectedness, another newly identified dimension, encapsulates feelings of universal love, intuitive insights into the nature of beings and objects, and an enhanced appreciation for beauty and interpersonal relationships. The experiences measured by this subscale resonate with the notion that psychedelics can dissolve the barriers that separate individuals from each other and from the natural world, promoting a sense of harmony and interconnectedness.
The visual experience subscale highlights another pivotal aspect of the psychedelic journey: the occurrence of vivid, often profound visual phenomena. This dimension encompasses both the perception of intricate geometric patterns and the transformation of ordinary objects into works of extraordinary beauty.
Lastly, the distressing experience subscale addresses the challenging aspects of psychedelic experiences, encompassing feelings of fear, despair, isolation, and physical discomfort. This dimension is a crucial addition to the understanding of psychedelics, acknowledging that these experiences are not universally positive or enlightening. Instead, they can also involve profound emotional turmoil and existential confrontation.
“With the PES, we have revived an old, expertly crafted questionnaire from the 1960s with modern, state-of-the-art analyses that allows us to capture essential aspects of the psychedelic experience better than his hitherto been possible within a single questionnaire,” Stocker explained. “Thus it is likely a useful tool in the ongoing research endeavor of identifying the whole range of possible beneficial aspects of the psychedelic experience.”
Interestingly, the MEQ includes transcendence of time and space as one of the four core components of mystical experiences induced by psychedelics. The new findings reaffirmed that transcendence of time and space is a critical dimension of the mystical experience. But the researchers also found evidence that such transcendental experiences might not always be part of what is traditionally considered a mystical experience.
“Feelings of transcendence of time and space (for example feelings that one experiences eternity or infinity and that one is in a realm with no space boundaries) is most often considered to be an inherent part of the mystical experience,” Stocker told PsyPost. “While we could also confirm the association between time/space-transcendence and mystical experience with correlational analysis in the current paper, our additional exploratory hierarchical-item-clustering analysis still pointed to a more general, also somewhat mystical independent concept of transcendence that might emerge during the psychedelic experience.”
“Results of our cluster analysis suggest that this larger overarching concept of transcendence includes the transcendence of time and space, but also goes beyond that by including also transcending notions of self, body, and maybe also thought. This part of the cluster analysis did not surprise me, as such or similar statements (for instance that timelessness and feeling bodiless go hand-in-hand) have been made by many mystics across history, for instance by the late-medieval theologian, philosopher, and mystic Meister Eckhart.”
“But what did surprise me is that the cluster analysis suggests that such an experience of transcendence might not inherently be a part of the mystical experience, but might be more an experience in its own right,” Stocker said. “If this turns out to be true in future studies, then this could be ‘big news’ for scholars of the mystical experience (e.g., psychologists, philosophers, religious-studies scholars, psychedelic-science scholars).”
The refinement of the PES is a potentially significant advancement in the field of psychedelic research, offering deeper insights into the nuanced experiences induced by these substances. However, like any scientific tool, the PES comes with its limitations.
“While the possibility of a both comprehensive and concise covering of the psychedelic experience with one single questionnaire seems conceivable, such a psychometric tool is currently not at hand,” Stocker said. “The PES is a major step in that direction (the best option available so far), but also the PES still has important gaps, especially when it comes to the autobiographical dimension of the psychedelic experience.”
“The PES, for instance, covers only parts of possible autobiographically relevant experiences that might occur during the psychedelic experience — it only hints at emotional breakthroughs and at what we sometimes call ‘personal problem addressing.’ The latter means, for example, that one sees personal problems from one or more new perspectives, or that one feels that personal problem(s) were dealt with in a constructive way during the psychedelic experience.”
“One of the next goals of the psychological work in our psychopharmacology research at the University Hospital Basel is a comprehensive measurement of the psychology of the psychedelic experience for both research and therapy, which will hopefully also result in a corresponding questionnaire,” Stocker explained. “However, in the meantime the PES serves the basic purpose of a comprehensive and concise capturing of the psychedelic experience rather well.”
The study, “The revival of the psychedelic experience scale: Revealing its extended-mystical, visual, and distressing experiential spectrum with LSD and psilocybin studies,” was authored by Kurt Stocker, Matthias Hartmann, Laura Ley, Anna M. Becker, Friederike Holze, and Matthias E. Liechti.
