The Hallucinogen Rating Scale: Updated Factor Structure in a Large, Multistudy Sample.
Abigail E. Calder, Clifford Qualls, Gregor Hasler, David Elmiger, Rick J. Strassman
Biological Psychiatry Global Open Science March 1, 2025 DOI: 10.1016/j.bpsgos.2024.100436 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Secondary analysis of existing data Peer reviewed |
|---|---|
| Sample size | 991 |
| Population | Participants from 18 publications who completed HRS questionnaires after taking one of 13 psychoactive substances |
| Topics | Philosophy of mind |
| Keywords | Psychedelics hallucinogens Entheogens Psychometrics measurement Assessment Factor analysis Hallucinogen rating scale Questionnaires Psychoactive substances Mental states Rating scales Phenomenology subj |
| Citations | 5 |
| Key points | The HRS resolved into 8 factors with good to excellent internal consistency that differentiated classic psychedelics from other substance classes, with the meaningfulness factor uniquely distinguishing psychedelics from all other drugs. |
Abstract
The Hallucinogen Rating Scale (HRS) has been widely used to measure the subjective effects of psychedelics and other psychoactive substances. Its advantages include a basis in phenomenological interviews and clinical studies, straightforward items, and broad coverage of psychedelic effects. Previous studies have attempted to resolve its factor structure but were limited by small samples of participants who took only one substance. We obtained 991 HRS questionnaires from the authors of 18 publications involving 13 psychoactive substances. Exploratory factor analysis was used to analyze its factor structure, and mixed-effects analyses of variance were used to compare HRS scores between drugs. The HRS resolved into 8 factors with good to excellent internal consistency and that intuitively map onto the effects of psychedelics. The factor model also showed good measures of fit that were superior to previous proposed models. Model factors were able to show dose responses for most drugs. Additionally, patterns of responses on the 8 factors significantly differentiated classic psychedelics, such as psilocybin and DMT, from other substance classes, including dissociatives such as ketamine and salvinorin A, empathogens such as MDMA, stimulants such as methylphenidate and amphetamine, and Δ9-tetrahydrocannabinol. The factor of meaningfulness also uniquely differentiated psychedelics from all other substances. These data show that the HRS is an intuitive and psychometrically sound tool for measuring the effects of psychedelic drugs, and it may also have utility for measuring the effects of other drugs and altered states of consciousness.
Comparable studies
Other observational and cohort studies on philosophy of mind, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The phenomenology of near-death experiences Subjects who reported near-death experiences | 1980 | Retrospective study | n = 78 |
| Visual Phenomenology of the LSD Flashback Persons with a history of LSD use | 1983 | Observational cohort | n = 123 |
| The neurophenomenology of neutral hypnosis. Individuals of high, medium, and low hypnotizability | 2013 | Observational cohort | n = 37 |
| The Phenomenology of Acute Organic Psychosis Patients with acute organic psychosis and acute schizophrenics | 1987 | Observational cohort | n = 148 |
| EEG oscillatory states as neuro-phenomenology of consciousness as revealed from patients in vegetative and minimally conscious states. Brain-damaged patients with disorders of consciousness and healthy-conscious subjects | 2012 | Observational cohort |
Citations in the library
Cited by 6
- OAV and 5D-ASC for Brazilian Portuguese: A validation and adaptation study. Journal of Psychopharmacology June 28, 2025
- The 3D-ASCr scale: A revalidation of the core dimensions of the Altered States of Consciousness Rating Scale 5D(11)-ASC for psychedelic research. Journal of Psychopharmacology December 26, 2025
- Salvinorin A and Salvia divinorum: Toxicology, Pharmacological Profile, and Therapeutic Potential. International Journal of Molecular Sciences June 11, 2025
- How to set up a psychedelic study: Unique considerations for research involving human participants. Neuroscience & Biobehavioral Reviews July 1, 2026
- Changes in neuroticism and values after naturalistic use of psychedelics and MDMA: a prospective survey study Journal of Affective Disorders Reports July 1, 2026
and 1 more in the library
Cites 43
- Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial Journal of Psychopharmacology November 30, 2016
- Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Psychopharmacology July 7, 2006
- Human hallucinogen research: guidelines for safety. Journal of Psychopharmacology July 1, 2008
- Psilocybin with psychological support for treatment-resistant depression: six-month follow-up. Psychopharmacology November 8, 2017
- Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomized placebo-controlled trial Psychological Medicine June 15, 2018
and 38 more in the library