title: Measuring the subjective: revisiting the psychometric properties of three rating scales that assess the acute effects of hallucinogens.
abstract: 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).
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: ICEERS Foundation (International Center for Ethnobotanical Education, Research and Services), Spain. jcbouso@iceers.org.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Bouso
authors.affiliation: Departamento de Evaluación y Calidad, Instituto de Adicciones, Madrid Salud, Ayuntamiento de Madrid, Spain.
authors.forename: Eduardo José
authors.initials: EJ
authors.lastname: Pedrero-Pérez
authors.affiliation: The College of Life Sciences and Medicine, University of Aberdeen, UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Gandy
authors.affiliation: Departamento de Psicología Biológica y de la Salud. Facultad de Psicología, Universidad Autónoma de Madrid, Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Alcázar-Córcoles
mesh_terms: D000328:Adult; D031581:Banisteriopsis / Q000737:chemistry*; D005163:Factor Analysis, Statistical; D005260:Female; D006213:Hallucinogens / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D004130:N,N-Dimethyltryptamine / Q000008:administration & dosage / Q000494:pharmacology*; D028321:Plant Preparations / Q000008:administration & dosage / Q000494:pharmacology; D011594:Psychometrics; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D006213:Hallucinogens; D028321:Plant Preparations; D004130:N,N-Dimethyltryptamine
keywords: Addiction Research Center Inventory (ARCI); Hallucinogen Rating Scale (HRS); Mystical Experience Questionnaire (MEQ); ayahuasca; psychedelics; psychometrics