Noncredible performance in individuals with external incentives: empirical derivation and cross-validation of the...

Using a known groups design, a new Minnesota Multiphasic Personality Inventory (MMPI-2) subscale, the 20-item Psychosocial Distress Scale (PDS), was empirically derived and cross-validated. The PDS demonstrated good classification accuracy between subjects under external incentive vs. no incentive conditions. In the initial calibration sample (N = 84) a cut score of ≥10 on the PDS was associated with good classification accuracy (85.7%), high specificity (90.0%), and adequate sensitivity (81.8%). Under cross-validation conditions (N = 83) a cut score of ≥10 on the PDS was also associated with nearly identical classification accuracy (86.5%), specificity (91.89%), and sensitivity (82.61%). A cut score of ≥12 was associated with 100% positive predictive power; that is, no false-positive errors in both the initial calibration sample and the subsequent cross-validation sample. The current study suggests that in addition to noncredible cognitive performance, civil litigants and disability claimants may overreport psychosocial complaints that can be identified and that the scale may generalize to other settings and patient groups.