Validation of the Imperial Psychedelic Predictor Scale

A new 9-item scale called the Imperial Psychedelic Predictor Scale (IPPS) predicts key features of the acute psychedelic experience. Analyzing four independent datasets (two online surveys with 741 and 836 participants, and two controlled administration studies with 30 and 28 participants), the scale showed good internal consistency and three factors: set, rapport, and intention. The IPPS significantly predicted mystical, challenging, and emotional breakthrough experiences. In one controlled dataset, set and rapport explained 40% of variance in mystical experience, and set alone explained 16% of variance in challenging experience. In another, rapport explained 9% of variance in emotional breakthrough. The scale may improve safety and therapeutic outcomes by forecasting response variability.

Study at a glance

Abstract

Access to psychedelic drugs is liberalizing, yet responses are highly unpredictable. It is therefore imperative that we improve our ability to predict the nature of the acute psychedelic experience to improve safety and optimize potential therapeutic outcomes. This study sought to validate the ‘Imperial Psychedelic Predictor Scale’ (IPPS), a short, widely applicable, prospective measure intended to be predictive of salient dimensions of the psychedelic experience. Using four independent datasets in which the IPPS was completed prospectively – two online surveys of ‘naturalistic’ use (N = 741, N = 836) and two controlled administration datasets (N = 30, N = 28) – we conducted factor analysis, regression, and correlation analyses to assess the construct, predictive, and convergent validity of the IPPS. Our approach produced a 9-item scale with good internal consistency (Cronbach’s α = 0.8) containing three factors: set, rapport, and intention. The IPPS was significantly predictive of ‘mystical’, ‘challenging’, and ‘emotional breakthrough’ experiences. In a controlled administration dataset (N = 28), multiple regression found set and rapport explaining 40% of variance in mystical experience, and simple regression found set explained 16% of variance in challenging experience. In another (N = 30), rapport was related to emotional breakthrough explaining 9% of the variance. Together, these data suggest that the IPPS is predictive of relevant acute features of the psychedelic experience in a broad range of contexts. We hope that this brief 9-item scale will be widely adopted for improved knowledge of psychedelic preparedness in controlled settings and beyond.