The psychometric high-risk strategy represents a useful methodologic adjunct to the traditional genetic high-risk research approach in the study of the etiology and development of schizophrenia. During the past 15 years, considerable research activity has focused on psychometrically identified individuals hypothesized to be en route to schizophrenia (i.e., putative schizotypes). The Perceptual Aberration Scale (PAS) has figured prominently in such prediction-oriented psychometric high-risk work. This report examines research using the PAS completed since 1987 that has established the instrument as a valid index for detecting liability for schizophrenia (or schizotypy) and as, arguably, the schizotypy index of choice for research. These results are presented and interpreted in light of Meehl's theoretical framework of schizotypy. Other measures of and assessment devices for schizotypy (schizophrenia-related liability) are identified. Of these other measures, the Chapmans' Magical Ideation Scale and the schizophrenia liability index of Moldin and colleagues are particularly well established. Methodologic suggestions for future psychometric high-risk and other work using objective measures of schizotypic psychopathology are offered. It is strongly recommended that future studies of schizotypy (or those in the planning stages, relying on psychometric detection methods use multiple psychometric indices to tap schizotypy or use a psychometric index in association with other promising biobehavioral markers of schizophrenia liability (e.g., sustained attentional deficits, eye movement dysfunction) for maximum efficiency in both location and definition of schizotypes.