Psychometric brahman, psychedelic science: Walter Stace, transnational Vedanta, and the Mystical Experience Questionnaire.

This article examines the foundational role of philosopher Walter Stace's typology of mystical experience in the Mystical Experience Questionnaire (MEQ), a key psychometric tool used in contemporary psychedelic research to quantify mystical states. It highlights the under-recognized influence of modern, transnational Vedanta—a Hindu philosophical tradition represented by figures such as Swami Vivekananda, Swami Prabhavananda, and Sri Aurobindo—on Stace's conceptualization of a "universal core" of mysticism, particularly his notions of undifferentiated unity and the introvertive and extrovertive forms of mystical experience. The article argues that while the MEQ is presented as a secular, culturally neutral instrument, it inherently embeds Vedantic perennialist ideas, shaping how mystical experiences are defined and measured in psychedelic science today. This historical and philosophical context is important for understanding the MEQ's theoretical assumptions and the cultural dimensions often elided in clinical research on psychedelic-induced mystical experiences.