WAIS-IV Digit Span variables: are they valuable for use in predicting TOMM and MSVT failure?

The Digit Span (DS) task in the Wechsler Adult Intelligence Scale-Fourth Edition differs substantially from earlier versions of the measure, with one of the major changes being the addition of a sequencing component. In the present investigation, the usefulness of the new sequencing task and other DS variables (i.e., DS Age-Scaled Score, DS Forward Total, DS Backward Total, and Reliable DS) was investigated with regard to the ability of these variables to predict negative response bias. Negative response bias was first defined and examined using below-cutoff performance on the Test of Memory Malingering (TOMM) (N = 99). Then, for comparison purposes, negative response bias was examined using below-cutoff performance on the Medical Symptom Validity Test (MSVT; N = 95). Study participants included primarily middle-aged outpatients at a Veterans Affairs medical center. Findings from this retrospective analysis showed that, regardless of whether the TOMM or the MSVT was used as the negative response bias criterion, of all the DS variables examined, DS Sequencing Total showed the best classification accuracy. Yet, due to its relatively low positive and negative predictive power, DS Sequencing Total is not recommended for use in isolation to identify negative response bias.