Data from 239 measurements reveals a new validated structure for assessing psychedelic experiences.
Four original factors of the Mystical Experience Questionnaire (MEQ30) were confirmed as reliable.
New subscales for non-MEQ items were identified: , , visual experience, and distressing experience.
Paradoxicality and connectedness showed strong correlations with the MEQ30 mystical subscale.
The addition of the new subscales increased the explained variance with the 5-Dimensional Altered States of Consciousness Scale (5D-ASC).
A cluster analysis supported the main findings and provided insights for future psychedelic psychometrics.
Simplified
BACKGROUND: Research with the Psychedelic Experience Questionnaire/Scale () focuses on questions relating to mystical experience (Mystical Experience Questionnaire (MEQ)). The psychometric potential of the non-MEQ items of the PES remains largely unexplored.
AIMS: We investigated whether the PES also yields subscales besides the MEQ30 subscales.
METHODS: Data from 239 PES measurements (140 healthy participants) from six studies with moderate to high doses of lysergic acid diethylamide and/or psilocybin were included. New subscales (with items other than MEQ30) were created and validated as follows: (1) theoretical derivation of candidate items; (2) removal of items with rare experiences; (3) exploratory factor analysis; and (4) confirmatory factor analysis. Correlations of subscales within the PES and between the PES and the 5-Dimensional Altered States of Consciousness Scale (5D-ASC) were performed. In addition, a cluster analysis using all items (except rare experiences) was performed.
RESULTS: The reliability of the four original factors of the MEQ30 was confirmed and four additional factors for the non-MEQ items were revealed: , , visual experience, and distressing experience. The first two additional factors were strongly correlated with the MEQ30 mystical subscale. Adding the new subscales to the MEQ30 subscales increased the explained variance with the 5D-ASC. The cluster analysis confirmed our main results and provided additional insights for future psychedelic psychometrics.
CONCLUSION: The study yields a new validated 6-factor structure for extended mystical experience (MEQ40: MEQ30 + Paradoxicality + Connectedness) and covers psychedelic experience as a whole more comprehensively than has hitherto been possible within a single questionnaire (PES48). The entire PES (PES100) can also be used for further future psychedelic-psychometric research.
Key numbers
100
Total Items
Total number of items in the revised .
140
Participants
Number of healthy participants included in the analysis.
4
New Subscales
Number of new subscales added to the beyond the traditional mystical experience.
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Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: M. E. Liechti is a consultant for Mind Medicine Inc.
