Integrating the Mystical Experience Questionnaire Into a Broader Psychometric Framework: English Validation of the Psychedelic Experience Scale and Comparison of Psilocybin and LSD Sessions Across Two Controlled Settings.

The eight-factor structure of the Psychedelic Experience Scale (PES48), which includes the Mystical Experience Questionnaire (MEQ30) and additional factors for paradoxicality, connectedness, visual experience, and distressing experience, is valid for use in English. Analysis of 280 measurements from 145 healthy participants in four placebo-controlled psilocybin studies found that six subscales have high internal consistency, one good, and one acceptable. Both the MEQ30 and MEQ40 models show acceptable to good model fits, with better fits in English than in German. All six MEQ40 scale means were higher in English data, suggesting that the PES48 provides a broader conceptualization of mystical and non-mystical psychedelic experiences, and that setting may influence mystical experience.

Study at a glance

Abstract

For English, the validated part of Psychedelic Experience Scale (PES48) is a four-factor structure called the Mystical Experience Questionnaire (MEQ30). The other validated part of the PES48 consists of four more factors: two more mystical factors (paradoxicality and connectedness, which together with the MEQ30 form the MEQ40), and two more non-mystical factors (visual experience and distressing experience). However, this latter four-factor part of the PES48 has thus far only been validated for the German version of the PES48. We investigated whether the overall eight-factor structure of the PES48 (which includes the MEQ30 four-factor structure) can also be validated, and thus potentially be put to good use in English. Data from 280 English PES measurements (145 different healthy participants) from four placebo-controlled studies with low to high doses of psilocybin were included. The reliability of the eight subscales was evaluated using measures of internal consistency. The validity of the factor structure was assessed through model fit indices from confirmatory factor analysis. English results were then also compared with the German PES validation data set from Stocker et al. (2024). Six of the eight subscales (mystical, positive mood, transcendence of time and space, ineffability, connectedness, distressing experience) of the English PES48 show high internal consistency, one subscale (paradoxicality) shows good, and one (visual experience) acceptable internal consistency. Both MEQ models (MEQ30 and MEQ40) show similar fits (acceptable to good model fits). In English, both MEQ models show better fits than in German. All six MEQ40 scale means of the English data are higher compared to German data. The findings suggest that the eight-factor PES48 is also a valid psychometric tool in English. With the MEQ40 part of the PES48, one can measure mystical experience with a still wider conceptual breath than with the MEQ30. Furthermore, one can also measure non-mystical visual and distressing states in an overall more comprehensive and broader conceptualization of the psychedelic experience. Higher MEQ40 scale means for the English than the German study participants could inspire future research into the role of setting in relation to mystical experience.