Construct Validity of the Misrepresentation Scales of the Psychological Screening Inventory

Abstract

This study provides construct validity evidence and reliabilities (consistency and stability) for 5 misrepresentation (response distortion) scales of the Psychological Screening Inventory (PSI; Lanyon, 1970, 1973, 1978) in assessing 3 constructs: exaggeration of psychopathology, exaggeration of personal virtue, and exaggeration of health problems. Using data from forensic cases, the existence and independence of these 3 constructs were confirmed in data from the MMPI–2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) and the Balanced Inventory of Desirable Responding (Paulhus, 1986, 1991). The PSI scales were then shown to load highly on these constructs. The PSI scales also showed the expected patterns when their mean scores were examined for 15 sets of responses from participant groups with varied motivations to misrepresent. We present receiver operating characteristic data to show the success of the scales in distinguishing between simulators and appropriate comparison groups. Using the same data, we also present classification accuracy in terms of positive predictive power and negative predictive power based on a sensitivity level of 90% and misrepresentation base rates of .20 and .10.