Detecting malingered performance on the Wechsler Adult Intelligence Scale: Validation of Mittenberg’s approach in traumatic brain injury

This study assesses the effectiveness of the Wechsler Adult Intelligence Scale (WAIS) performance validity markers devised by Mittenberg et al. [Prof. Psychol.: Res. Pract. 26 (1995) 491] in the detection of malingered neurocognitive dysfunction (MND). Subjects were 65 traumatic brain injury (TBI) patients referred for neuropsychological evaluation. Twenty-eight met the Slick et al. [Clin. Neuropsychol. 13 (1999) 545] criteria for at least probable MND. The control group was comprised of 37 patients without external incentive and who thus did not meet the Slick et al. criteria. All subjects completed the Wechsler Adult Intelligence Scale-Revised (WAIS-R or WAIS-III). The discriminant function score (DFS) and the vocabulary–digit span (VDS) difference score were calculated and sensitivity, specificity, and predictive power were examined for several cut-offs for each marker individually and the two combined. Classification accuracy for the DFS was acceptable and better than for VDS. The use of the two markers in combination resulted in no incremental increase in classification accuracy. Issues related to the clinical application of these techniques are discussed.