Developing a spatial analogue of the reliable digit span.

It is recommended that performance validity be assessed in all neuropsychological cases involving external incentive. The present study sought to develop an embedded performance validity measure based on the Spatial Span task of the Wechsler Memory Scale-III in a sample of litigating persistent postconcussion complainants. The Reliable Spatial Span (RSS) calculation had specificity, sensitivity, and predictive power values within the range of other embedded measures. This finding suggests that RSS is able to distinguish between persistent postconcussion complainants demonstrating valid and invalid performance. Other calculations involving Spatial Span scores had lower classification accuracy. Reliable Digit Span (RDS) classification accuracy within the present sample was lower than that of previous research, as well as of RSS. Potential reasons for lack of RDS replication are discussed, along with the potential use of RSS as an embedded validity performance indicator.