Validity of VSVT and reliable digit span measures for detecting malingering in groups differing exposure to and knowledge of TBI
Date
2000
Authors
Levy-Bencheton, Judith
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Abstract
Recent empirical findings (Strauss et al., 1999) demonstrated the potential utility in examining variability in performance to diagnose malingering using a standard neuropsychological measure and a forced choice symptom validity task. However, Strauss et al. (1999) used an analog paradigm in which they did not examine the potential contribution of knowledge of head injuries (through direct experience with head-injured individuals or having received a head injury oneself) to malingering status. The main purposes of this thesis include providing cross-validation for the neuropsychological measure and the Victoria Symptom Validity Task (VSVT) in detecting malingering status, examining the contribution of variability in performance to detecting malingering, as well as examining of the impact of knowledge on malingering status. A sample of 74 participants (27 head-injured adults, 26 naive people, and 21 experienced individuals) was recruited from advertisements and newspaper ads. The participants ranged in age from 18 to 57 years (M = 36.24, SD= 9.68). All participants provided demographic and health-related information. They also completed a battery of cognitive tests including the MMSE (Folstein, Folstein, & McHugh, 1975), the Wechsler Adult Intelligence Scale-III (WAIS-III) Block Deign and Vocabulary subtests (Psychological Corporation, 1997), and the North American Adult Reading Test (NAART, Blair and Spreen, 1989) in order to obtain benchmark cognitive measures. The study took place across four occasions, consisting of an initial interview and three test sessions. Following the initial interview, participants were randomly assigned to one of two experimental groups: malingerers and controls. Participants were tested individually over three measurement occasions scheduled approximately two weeks apart. The dependent measures of interest included the VSVT and the RDS .
The results indicated that multiple measures of malingering (VSVT and RDS) obtained in a single assessment ( occasion one, two or three) discriminated the groups effectively. In addition, however, intraindividual variability in performance (on both tasks) provided unique information beyond level of performance. There was no effect of knowledge in detecting malingering status. The results suggest that response inconsistency across testing sessions may be a clinically useful measure for the detection of malingering.