Expansion and Re-examination of Digit Span Effort Indices on the WAIS-IV

The Digit Span subtest was significantly revised for the WAIS-IV as an ordinal sequencing trial was added to increase working memory demands. The present investigation sought to validate an expanded version of Reliable Digit Span (RDS-R) as well as age-corrected scaled score (ACSS) from the recently revised Digit Span. Archival data were collected from 259 veterans completing the WAIS-IV Digit Span subtest and Word Memory Test (WMT). Veterans failing the WMT performed significantly worse (p<.001) on the ACSS, RDS-R, and traditional RDS. Operational characteristics of the ACSS, RDS-R, and RDS were essentially equivalent; however, sensitivity was quite modest when selecting cutoffs with strong specificity. While current results suggest that Digit Span effort indices can contribute to the detection of suboptimal effort, additional symptom validity indicators should be employed to compensate for limited sensitivity.