Abstract

Objective: This project sought to examine the continued validity of Digit Span (DS) embedded measures as indicators of non-credible effort and further explore whether patterns of performance on the sequencing trial of the WAIS-IV DS subtest add incrementally to the established Reliable Digit Span (RDS) for assessing effort. Method: The litigant sample consisted of 98 archived outpatient neuropsychological evaluations that included a WAIS-IV protocol as part of assessment proceedings for traumatic brain injury, and a final clinical determination of the evaluator which did not utilize DS scores as part of the determination. Cases were divided into malingered neurocognitive dysfunction (MND) and non-malingering groups. ROC analysis was performed for standard RDS (DSF + DSB) as well as additional variants of Alternate RDS (DSF + DSS) and Enhanced RDS (DSF + DSB + DSS) proposed by Reese, Suhr, and Riddle (2012). Results: The AUC for standard RDS was observed to be .798 with a cut-score 6 producing sensitivity of 31.8% and specificity of 90.6%. The AUC for Alternate RDS was observed to be .836 with a cut-score of 8 producing sensitivity 72.7% and specificity of 81.1%. The AUC for Enhanced RDS was observed to be .854 with a cut-score of 10 producing sensitivity 45.5% and specificity of 88.7%. Conclusion(s): Results from this study indicate that DS variables, particularly Enhanced RDS, from the WAIS-IV continue to perform well as embedded measures of performance validity. Results from this study suggest further investigation of the Enhanced RDS measure to further establish validity for use in clinical practice.