No abstract

The present study aimed to develop an internal validity indicator for a brief general purpose screening battery, the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Two subtests of the RBANS were predicted to be relatively resilient to cognitive dysfunction on the basis of previous research. An Effort Index (EI) was created by combining them via a scaling system. The frequency of EI scores was first examined in a heterogenous clinical sample. A subsequent validation study showed good discriminability. In conclusion, the EI appears to be useful for detecting insufficient effort on a screening battery.

The current study evaluated the utility of the Digit Span subtest in discriminating patients with mild head trauma from individuals referred for independent neuropsychological evaluation with objective evidence of poor effort. Various indices from the Digit Span subtest were evaluated to determine the best discriminator of brain injury from poor motivation patient groups: Digit Span Forward, Digit Span Backwards, Reliable Digit Span, Digit Span Age-Corrected Scaled Score, and the difference score between the Vocabulary and Digit Span scaled scores. The Digit Span scaled score was found to be the best discriminating index. A cutoff score of less than or equal to 7 accurately classified 75% of persons in the incomplete effort group and 69% of persons in the TBI group. Application of this cutoff score to a non-litigating mild brain injury group yielded a 77% correct classification rate. However, Digit Span scaled score accounted for a modest amount of variation and it is not recommended as a stand-alone validity measure.