An examination of the frequency of invalid forgetting on the Test of Memory Malingering.

The Test of Memory Malingering (TOMM) is the most used performance validity test in neuropsychology, but does not measure response consistency, which is central in the measurement of credible presentation. Gunner, Miele, Lynch, and McCaffrey (2012) developed the Albany Consistency Index (ACI) to address this need. The ACI consistency measurement, however, may penalize examinees, resulting in suboptimal accuracy. The Invalid Forgetting Frequency Index (IFFI), created for the present study, utilizes an algorithm to identify and differentiate learning and inconsistent response patterns across TOMM trials. The purpose of this study was to assess the diagnostic accuracy of the ACI and IFFI against a reference test (Malingered Neurocognitive Dysfunction criteria), and to compare both to the standard TOMM indexes. This retrospective case-control study used 59 forensic cases from an outpatient clinic in Southern Kansas. Results indicated that sensitivity, negative predictive value, and overall accuracy of the IFFI were superior to both the TOMM indexes and ACI. Logistic regression odds ratios were similar for TOMM Trial 2, Retention, and IFFI (1.25, 1.24, 1.25, respectively), with the ACI somewhat lower (1.18). The IFFI had the highest rate of group membership predictions (79.7%). Implications and limitations of the present study are discussed.