The 3D-ASCr scale: A revalidation of the core dimensions of the Altered States of Consciousness Rating Scale 5D(11)-ASC for psychedelic research.

Abstract

The Altered States of Consciousness Scale (3/5D-ASC or 11-ASC) is widely used to assess non-ordinary states of consciousness, particularly for psychedelic research. However, its original dimensional model (3D-ASC within 5D-ASC) and later 11-subscale structure (11-ASC) have a hierarchically incompatible higher/lower-order structure. Although the 11-ASC offers superior model fit, the 3D-ASC remains widely used for summarizing broader experiential domains. We wanted to provide an updated, psychometrically revalidated version of the ASC. We tested whether the 42-item 11-ASC could be integrated into a coherent three-dimensional framework. We further hypothesized that this revised model would outperform the original 66-item 3D-ASC while preserving its conceptual clarity. Data from 901 5D-ASC questionnaires from 398 healthy participants across 16 randomized, mostly placebo-controlled psychedelic (lysergic acid diethylamide, psilocybin, mescaline, and N,N-dimethyltryptamine) studies were split for exploratory and confirmatory factor analysis. We compared the 3D-ASC and 11-ASC in terms of reliability and model fit, and tested whether the 11-ASC could be summarized within a three-dimensional model. Ten of the 11 subscales formed three higher-order dimensions-Positive (PosE), Distressing (DisE), and Perceptual (PerE) effects-mirroring the 3D-ASC but with improved fit. We propose this as the 3D-ASCr scale. The Anxiety subscale could not be integrated due to consistent floor effects (low anxiety in the sample), but given its clinical relevance, it is retained within 3D-ASCr (as part of DisE or a standalone subscale). The 3D-ASCr is an updated version of the ASC and is recommended for use with classic serotonergic psychedelics in both clinical practice and research.