Preliminary evidence for digit span performance validity indicators within the neuropsychological assessment battery

The purpose of this study was to evaluate multiple embedded performance validity indicators within the Digits Forward and Digits Backward subtests of the Neuropsychological Assessment Battery (NAB), including Reliable Digit Span (RDS), as no published papers have examined embedded digit span validity indicators within these subtests of the NAB. Retrospective archival chart review was conducted at an outpatient neuropsychology clinic. Participants were 92 adults (ages 19-68) who completed NAB Digits Forward and Digits Backward, and the Word Choice Test (WCT). Receiver operating characteristic (ROC) curves, t-tests, and sensitivity and specificity analyses were conducted. Analyses showed that RDS demonstrated acceptable classification accuracy between those who passed the WCT and those who did not. The area under the curve (AUC) value for RDS was 0.702; however, AUC values for all other digit span indices were unacceptably low. The optimal cutoff for RDS was identified (<8). RDS for the NAB appears to be an adequate indicator of performance validity; however, considering the very small number of participants who were invalid on the WCT (n = 15), as well as the utilization of only one stand-alone PVT to classify validity status, these findings are preliminary and in need of replication.