The study’s approach to mysticism seems to be rather qualitative than quantitative, based on self reporting and questionnaires, mostly from members of MAPS, whom probably have certain variables that aren’t really controlled for compared to the general population.
Mysticism Scale. This 32-item questionnaire (Hood 1975) contains items that ask participants about past mys- tical experiences (if any). The Mysticism Scale has been used in research on the psychology of religion (Spilka et al. 2003) but has only previously been applied to drug experiences by Griffiths and colleagues (2006), who used it to assess psychedelic drug (psilocybin) experiences. The Mysticism Scale yields a total score based on three dimen- sions of mystical experience: noetic quality (e.g., “I have never experienced anything to be divine,” reverse-scored); introvertive mysticism (e.g., “I have never had an experi- ence which I was unable to express adequately through lan- guage,” reverse-scored); and extrovertive mysticism (e.g, “I have had an experience in which I felt everything in the world to be part of the same whole”). The items are rated on a nine-point scale ranging from −4 = “this description is extremely not true of my own experience or experiences” through 0 = “I cannot decide” to +4 = “this description is extremely true of my own experience or experiences.” The psychometric properties of this scale have been reported to be sound (Reinert & Steifler 1993).
The study’s approach to mysticism seems to be rather qualitative than quantitative, based on self reporting and questionnaires, mostly from members of MAPS, whom probably have certain variables that aren’t really controlled for compared to the general population.