Detecting malingering in a clinical sample with the Wechsler Memory Scale-Revised

James William Irby

Abstract

In an effort to replicate the findings of Mittenberg et al. (1993) in a clinical sample, patterns of performance on the General Memory Index (GMI) and the Attention/Concentration Index (ACI) of the Wechsler Memory Scale-Revised (WMS-R) were examined in three groups of mild head-injured patients. Nineteen patients were non-litigants. All of the remaining 53 patients were involved in litigation. Of those, 20 were suspected of malingering based on their performance on forced-choice testing, and 33 patients were not suspected of malingering based on their performance on forced-choice testing. The results indicated that the suspected-malingering group performed significantly lower on both the GMI and ACI than did either of the other groups. The difference between the GMI and the ACI (GMI-ACI) for the suspected malingering group was also significantly larger than it was for the non-litigant group. No significant differences were observed on the GMI, the ACI, or GMI-ACI difference score between the non-litigant group and the litigant group that was not suspected of malingering. Also, no significant difference was observed between the two litigant groups on the GMI-ACI difference score. No significant correlations were found between the forced-choice measures and the GMI-ACI difference score. The overall results of the study support the findings of Mittenberg et al. (1993), who observed that individuals who were instructed to simulate malingering, reversed the characteristic General Memory Index < Attention/Concentration Index pattern that is typically observed in traumatically brain-injured patients. When compared to mild head-injured individuals who were not involved in litigation, mild head-injured individuals who were involved in litigation, and who were suspected of malingering, overestimated the degree of their expressed attentional impairment, relative to their general memory performance.