Examining the item composition of the RBS in veterans undergoing neuropsychological evaluation

The Response Bias Scale (RBS) is a measure of protocol validity that is composed of items from the Minnesota Multiphasic Personality Inventory - 2. The RBS has been successfully cross-validated as a whole, but the composition of the scale has not been reexamined until recently when three types of items were identified. In this study we sought to examine the reliability of the scale as a whole, as well as the items that are (a) empirically supported and conceptually similar (ES/CS), (b) empirically supported but not conceptually similar (ES/NS), and (c) not empirically supported (NES). Participants included 56 veterans undergoing neuropsychological evaluation for suspected traumatic brain injury. Results generally replicated Ratcliffe et al. finding that removing key NES items improved the internal consistency of the RBS from 0.706 to 0.747. Examined separately, ES/CS and ES/NS had internal consistencies of 0.629 and 0.605, respectively. One of the nine NES items had strong internal consistency, but none of the remaining eight had corrected item-total correlations above 0.194. NES items had an internal consistency of 0.177. Although the RBS is well-validated in detecting non-credible cognitive presentations, it may prove even more valuable after further item refinement whereby items detracting from its reliability and validity are excised.