The criterion and discriminant validity of the Referential Thinking (REF) scale

The Referential Thinking (REF) scale was designed to be a comprehensive self-report measure of both simple and guilty ideas of reference in the general population. One aim of the present study was to test the proposed interpretations of REF scores by comparing REF scores with ratings of delusions among psychotic patients. A 2nd aim was to test whether REF scores are better predicted by the severity of patients' delusions of reference (DoRs) than by the severity of their auditory verbal hallucinations (AVHs), thus supporting the scores' ability to discriminate between proneness to the 2 different symptoms. The REF scale was completed by 56 healthy controls and 53 acutely psychotic patients. The severity of the patients' DoRs and AVHs were assessed in structured clinical interviews. REF scores differed significantly not only between the patients and controls but also between patients with versus without DoRs. REF scores correlated significantly with the severity of the patients' DoRs but not their AVHs. The interpretation of REF scores as a measure of proneness to simple and guilty ideas of reference was supported.