The Cardiff Anomalous Perceptions Scale (CAPS): a new validated measure of anomalous perceptual experience

Abstract

The study describes the Cardiff Anomalous Perceptions Scale (CAPS), a new validated measure of perceptual anomalies. The 32-item CAPS measure is a reliable, self-report scale, which uses neutral language, demonstrates high content validity, and includes subscales that measure distress, intrusiveness, and frequency of anomalous experience. The CAPS was completed by a general population sample of 336 participants and 20 psychotic inpatients. Approximately 11% of the general population sample scored above the mean of the psychotic patient sample, although, as a group, psychotic inpatients scored significantly more than the general population on all CAPS subscales. A principal components analysis of the general population data revealed 3 components: "clinical psychosis" (largely Schneiderian first-rank symptoms), "temporal lobe disturbance" (largely related to temporal lobe epilepsy and related seizure-like disturbances) and "chemosensation" (largely olfactory and gustatory experiences), suggesting that there are multiple contributory factors underlying anomalous perceptual experience and the "psychosis continuum."

Fig. 1.

Frequency distribution of CAPS total score for clinical and nonclinical samples.

Fig. 2.

CAPS scores for nonclinical participants and psychotic inpatients. When compared using an independent samples 2-tailed t-test, psychotic inpatients differ significantly from the nonclinical sample on all subscales by at least p < .0005.