Preliminary findings from reevaluating the MMPI Response Bias Scale items in veterans undergoing neuropsychological evaluation

Abstract

The Response Bias Scale (RBS) was developed to predict non-credible cognitive presentations among disability claimants without head injury. Developers used empirical keying, which is independent of apparent content, to select items from the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) item pool that distinguished between individuals passing or failing performance validity tests (PVTs). No study has examined which of these items would have psychometric value when used in clinical neuropsychological evaluations. This study reexamined items comprising RBS with reference to manifest item content, internal consistency, PVTs, and a symptom validity test (SVT) in a sample of 173 predominately White male veterans (MAGE = 50.70, MEDU = 13.73) in a VA outpatient neuropsychology clinic. Participants completed the MMPI-2 Restructured Form (MMPI-2-RF), PVTs, and an SVT. The 28-item RBS appears to contain three types of items: those that manifestly address cognitive functioning, those that are supported but do not appear to address cognitive functioning, and nine items that were unrelated to cognition and not statistically supported. The 19 empirically supported items, or RBS-19, predicted PVT and SVT failures marginally better than the RBS. Both the RBS and RBS-19 had stronger relationships with SVTs relative to PVTs. Although the removal of the nine problematic items improved the diagnostic accuracy of the scale, it still did not reach the level that is generally considered to be clinically optimal. The RBS-19 offers a measure with improved internal consistency and predictive validity compared to the RBS and warrants additional research.