Digit Span Raw, A Newly Derived Embedded Performance Validity Test

Abstract Objective Outside of Reliable Digit Span (RDS), there has been minimal research examining the utility of Digit Span (DS) score combinations from the Wechsler Adult Intelligence Scale—4th Edition (WAIS-IV) as possible performance validity tests (PVTs). We sought to determine if other DS scores/score combinations might work more effectively than RDS as a PVT. Method Patients included 318 individuals who completed neuropsychological evaluations. Individuals were excluded if they were not administered DS; were not administered at least 4 criterion PVTs; had diagnoses of dementia, intellectual disability, or left hemisphere cerebrovascular accident; or had indeterminate validity results (i.e., failure of one PVT). Valid performers (n = 248) were those who passed all criterion PVTs while invalid performers (n = 70) failed two or more criterion PVTs. Receiver operating characteristic curves were conducted for multiple DS indices. Results Area under the curve (AUC) was highest for the DS index that combined raw scores from all three trials (Digit Span Raw; AUC = .821). Likewise, when examining cutoffs that maintained 90% specificity for each DS index, a Digit Span Raw cutoff of < 20 produced the highest sensitivity rate (52%) of all indices. For comparison, RDS, RDS with sequencing, and DS scaled score had AUC values of .758, .802, and .811, respectively. When maintaining specificity at 90%, sensitivity rates were 28%, 43%, and 43%, respectively. Conclusions Results suggest that the most effective embedded DS index might be a new one, which we term Digit Span Raw. Cross-validation of these findings could provide support for using this index instead of the more commonly examined RDS.