Development and preliminary validation of a brief behavioral measure of psychotic propensity.

•Describes a normed method to behaviorally assess just disordered thinking and aberrant perception.•Uses the Rorschach inkblot task with equated sets of 10, 5, 4, or 3 cards.•Reliability and validity demonstrated in 3 patient and 1 nonpatient samples.•Repeat assessments possible with non-overlapping short forms.