Measuring the subjective: revisiting the psychometric properties of three rating scales that assess the acute effects of hallucinogens

Written by: José Carlos Bouso, Eduardo José Pedrero-Pérez, Sam Gandy, Miguel Ángel Alcázar-Córcoles

Objective: In the present study we explored the psychometric properties of three widely used questionnaires to assess the subjective effects of hallucinogens: the Hallucinogen Rating Scale (HRS), the Mystical Experience Questionnaire (MEQ), and the Addiction Research Center Inventory (ARCI).

Methods: These three questionnaires were administered to a sample of 158 subjects (100 men) after taking ayahuasca, a hallucinogen whose
main active component is N,N-dimethyltryptamine (DMT). A confirmatory factorial study was conducted to check the adjustment of previous
data obtained via theoretical proposals. When this was not possible, we used an exploratory factor analysis without restrictions, based on tetrachoric and polychoric matrices and correlations.

Results: Our results sparsely match the theoretical proposals of the authors, perhaps because previous studies have not always employed
psychometric methods appropriate to the data obtained. However, these data should be considered preliminary, pending larger samples to
confirm or reject the proposed structures obtained.

Conclusions: It is crucial that instruments of sufficiently precise measurement are utilized to make sense of the information obtained in the study of the subjective effects of psychedelic drugs. Copyright © 2016 John Wiley & Sons, Ltd.

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