The purpose of this study was to examine the clinical utility of memory minus Working Memory Index (memory-WMI) discrepancy scores on the WMS-III for detecting poor effort in 145 personal injury litigants (19 poor effort, 126 adequate effort). On average, participants in the poor effort group performed significantly lower on all WMS-III memory indexes and demonstrated larger memory-WMI discrepancy scores compared to participants in the adequate effort group. Discriminant function analyses using memory-WMI discrepancy scores as independent variables revealed poor overall classification rates (60.0% to 63.4%). Based on the prevalence of unusually suppressed attention-concentration ability relative to memory functioning using unidirectional memory-WMI discrepancy scores, high specificity and negative predictive power values were found. However, there was unacceptably low sensitivity and positive predictive power. These results suggest that memory-WMI discrepancy scores on the WMS-III do not provide clinically useful information regarding response set and should be used cautiously as an indicator of poor effort.
Portions of these data were presented at the International Neuropsychological Society annual conference, February 2004, Baltimore, MD, USA.
This study was supported in part by a research grant from the Queensland University of Technology, Brisbane, Australia.
Notes
Portions of these data were presented at the International Neuropsychological Society annual conference, February 2004, Baltimore, MD, USA.
This study was supported in part by a research grant from the Queensland University of Technology, Brisbane, Australia.
1The data collected for this investigation was obtained from referrals during 1998 to 2003. In earlier years, the standard practice of the clinician was to refrain from administering well-validated symptom validity tests (e.g., TOMM) unless concerns were raised during testing regarding motivation. On many occasions the Rey 15 item test was administered. However, given the demonstrated limitations of this test, individuals who were administered the Rey 15 Item test were not included. It is acknowledged that this criteria for exclusion may ultimately produce a selection bias towards the inclusion of individuals who are more likely to be exaggerating. However, analysis of the data using the entire sample did not change the results or conclusions of this study. Data pertaining to the entire sample can be obtained from the authors on request.