New measures to detect malingered neurocognitive deficit: Applying reaction time and event-related potentials

Abstract

The ability of the Test of Memory Malingering (TOMM), reaction times (RT) and Event-Related Potentials (ERP) to detect malingered neurocognitive deficit (MNCD) was examined in 32 normal individuals answering under honest (HON; n = 16) or malingering instructions (MAL; n = 16) as well as in 15 patients with Traumatic Brain Injury (TBI) who answered under honest instructions. Overall, the TOMM was the most effective at classifying groups. However, new accuracy, RT, and ERP measures reached promising hit rates in the range of 71%-88%. In particular, the difference in frontal versus posterior ERP obtained during an old-new task was effective at classifying MAL vs. TBI (hit rate = 87%).In the Diagnostic and Statistical Manual of Mental Disorders, IVth Edition, Text Revision (APA, 2000), malingering is defined as the deliberate fabrication or gross exaggeration of physical or psychological symptoms in pursuit of external goals such as avoiding duty or obtaining financial compensation. Malingering is distinguished from Somatoform Disorders in that in the latter, symptoms are not thought to be under voluntary control and are produced in pursuit of internal goals, such as resolving unconscious conflicts. Malingering is discriminated from Factitious Disorder in that in the latter, although symptoms are consciously produced, they appear to be in pursuit of internal goals such as achieving the sick role.Malingered symptoms have been of increasing concern in neuropsychological assessment because most cognitive tests require optimal effort from the evaluee in order to achieve results that accurately reflect brain functioning. In situations in which patients are being evaluated for disability pensions or monetary compensation for damages sustained in accidents, the potential motivation to exaggerate or even fabricate problems is obvious. In fact, surveys of forensic neuropsychologists have suggested that up to 40% of individuals undergoing evaluations following mild head injuries may be malingering deficits (Mittenberg, Patton, Canyock & Condit, 2002).Neuropsychologists have responded to this concern by developing and validating a number of tests for the identification of inadequate effort during neuropsychological examinations. Vickery et al. (2001) published a meta-analysis of widely studied malingering tests and found that most had large effect sizes, high specificity (percentage of honest patients correctly classified) and moderate sensitivity (percentage of feigners correctly classified). However, recently, concerns have been raised that unscrupulous parties to legal proceedings may be "coaching" plaintiffs to avoid being detected by commonly used malingering tests TOMM;Tombaugh, 1996), other approaches have explored aspects of the evaluee's responses that are under less conscious control, such as reaction time (RT) and brain activity using electroencephalograph (EEG). In general, these two approaches hypothesize that the physiologic markers of neural processes that are normally "automatic" in cooperative test-t...

Keeping an eye on the truth? Pupil size changes associated with recognition memory

“…A similar argument has been made concerning the ERP old/new effect, and has been used to support its potential use as an index of malingering (Tardif et al, 2000;van Hooff et al, 2009). In a recent study, however, the ERP old/new effect was not observed in a group of participants instructed to malinger (Vagnini, Berry, Clark, & Jiang, 2008). Differences in procedure, in particular whether participants were asked to feign amnesia before or after learning the word list, may account for the different findings.…”

Detecting memory performance validity with DETECTS: A computerized performance validity test

“…Participants in the normative group were faster when providing correct responses, possibly because they were unsure of their wrong answers and this decision-making process under uncertainty may take additional time. Simulators, however, provided incorrect responses as fast as correct responses because, as stated above, their simulation strategy may be to purposely try to always respond slowly (Vagnini et al, 2008). Thus, the simulators' response time was intentionally higher than the time they would actually need to discriminate between a correct and an incorrect response regardless of accuracy.…”

“…Computerized PVTs are becoming more common and can have several advantages over traditional PVTs (Vanderslice-Barr, Miele, Jardin, & McCaffrey, 2011) such as precise measuring of response time (Bianchini et al, 2001;Haines & Norris, 1995;Vagnini, Berry, Clark, & Jiang, 2008;Willison & Tombaugh, 2006). Measuring response time can be very important, since a common strategy used by malingerers and simulators is to intentionally respond more slowly.…”

Impact of stimulus similarity between the probe and the irrelevant items during a card-playing deception detection task: The “irrelevants” are not irrelevant

“…Within the last two decades, there has been increasing interest in the use of neurophysiological measures in order to detect malingering and deception (e.g., Appelbaum, 2007;Gaetz, 2002;Ganis & Keenan, 2009;Rosenfeld, 2002;Vagnini, Berry, Clark, & Jiang, 2008). One of the main draws of using neurophysiological measures is the assumption that humans exert less control over their cognitive processes than over their behavioral and verbal responses, and hence these techniques may provide an alternative mode for the identification of deception.…”