Detecting simulated versus bona fide traumatic brain injury using pupillometry.

Objective: Pupil dilation patterns are outside of conscious control and provide information regarding neuropsychological processes related to deception, cognitive effort, and familiarity. This study examined the incremental utility of pupillometry on the Test of Memory Malingering (TOMM) in classifying individuals with verified traumatic brain injury (TBI), individuals simulating TBI, and healthy comparisons. Method: Participants were 177 adults across three groups: verified TBI (n = 53), feigned cognitive impairment due to TBI (SIM, n = 52), and heathy comparisons (HC, n = 72). Results: Logistic regression and ROC curve analyses identified several pupil indices that discriminated the groups. Pupillometry discriminated best for the comparison of greatest clinical interest, verified TBI versus simulators, adding information beyond traditional accuracy scores. Simulators showed evidence of greater cognitive load than both groups instructed to perform at their best ability (HC and TBI). Additionally, the typically robust phenomenon of dilating to familiar stimuli was relatively diminished among TBI simulators compared to TBI and HC. This finding may reflect competing, interfering effects of cognitive effort that are frequently observed in pupillary reactivity during deception. However, the familiarity effect appeared on nearly half the trials for SIM participants. Among those trials evidencing the familiarity response, selection of the unfamiliar stimulus (i.e., dilation-response inconsistency) was associated with a sizeable increase in likelihood of being a simulator. Conclusions: Taken together, these findings provide strong support for multimethod assessment: adding unique performance assessments such as biometrics to standard accuracy scores. Continued study of pupillometry will enhance the identification of simulators who are not detected by traditional performance validity test scoring metrics. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Performance validity assessment using response time on the Warrington Recognition Memory Test.

OBJECTIVE: The present study tested the incremental utility of response time (RT) on the Warrington Recognition Memory Test - Words (RMT-W) in classifying bona fide versus feigned TBI. METHOD: Participants were 173 adults: 55 with moderate to severe TBI, 69 healthy comparisons (HC) instructed to perform their best, and 49 healthy adults coached to simulate TBI (SIM). Participants completed a computerized version of the RMT-W in the context of a comprehensive neuropsychological battery. Groups were compared on RT indices including mean RT (overall, correct trials, incorrect trials) and variability, as well as the traditional RMT-W accuracy score. RESULTS: Several RT indices differed significantly across groups, although RMT-W accuracy predicted group membership more strongly than any individual RT index. SIM showed longer average RT than both TBI and HC. RT variability and RT for incorrect trials distinguished SIM-HC but not SIM-TBI comparisons. In general, results for SIM-TBI comparisons were weaker than SIM-HC results. For SIM-HC comparisons, classification accuracy was excellent for all multivariable models incorporating RMT-W accuracy with one of the RT indices. For SIM-TBI comparisons, classification accuracies for multivariable models ranged from acceptable to excellent discriminability. In addition to mean RT and RT on correct trials, the ratio of RT on correct items to incorrect items showed incremental predictive value to accuracy. CONCLUSION: Findings support the growing body of research supporting the value of combining RT with PVTs in discriminating between verified and feigned TBI. The diagnostic accuracy of the RMT-W can be improved by incorporating RT.

Detecting feigned traumatic brain injury with eye tracking during a test of performance validity.

OBJECTIVE: Eye-tracking is a promising technology to enhance assessment of performance validity. Research has established that ocular behaviors are reliable biomarkers of (un)conscious cognitive processes, and they have distinguished deceptive from honest responding in experimental paradigms. This study examined the incremental utility of eye-tracking on a clinical performance validity test (PVT) in distinguishing adults with verified TBI from adults coached to feign cognitive impairment. METHOD: Participants were 49 adults with moderate-to-severe TBI (TBI), 47 healthy adults coached to simulate TBI (SIM), and 67 healthy comparisons providing full effort (HC). A PVT linked to eye-tracking was completed in the context of a full neuropsychological battery. RESULTS: Kruskal-Wallis tests revealed that eye-tracking indices did not differ among the groups during presentation of stimulus items but did differ during forced-choice trials. Compared to TBI and HC, SIM had significantly more transitions, fixations, and time spent looking at correct and incorrect response options. Logistic regressions and ROC curve analyses showed that accuracy was the best predictor of SIM versus HC. For SIM versus TBI, eye-tracking indices exceeded accuracy in distinguishing the groups. Eye-tracking added incremental predictive value to accuracy for both SIM-HC and SIM-TBI discriminations. CONCLUSION: Eye-tracking indicated that persons feigning TBI showed multiple signs of greater cognitive effort than persons with verified TBI and healthy comparisons. In the comparison of greatest interest (SIM vs. TBI) eye-tracking best predicted group status and yielded excellent discrimination when combined with accuracy. Eye-tracking may be an important complement to traditional accuracy scores on PVTs. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Detecting malingering in traumatic brain injury: Combining response time with performance validity test accuracy.

OBJECTIVE: The present study examined the incremental utility of item-level response time (RT) variables on a traditional performance validity test in distinguishing adults with verified TBI from adults coached to feign neurocognitive impairment. METHOD: Participants were 45 adults with moderate to severe TBI, 45 healthy adults coached to feign neurocognitive impairment (SIM), and 61 healthy adult comparisons providing full effort (HC). All participants completed a computerized version of the Test of Memory Malingering (TOMM-C) in the context of a larger test battery. RT variables examined along with TOMM-C accuracy scores included mean RTs (Trial 1, Trial 2, correct and incorrect trials) and RT variability indices. RESULTS: Several RT indices differed significantly across the groups. In general, SIM produced longer, more variable RTs than HC and TBI. Of the RT indices, average RT for Trial 1 and 2 were the best predictors of group membership; however, classification accuracies were greatly influenced by the groups being compared. Average RT for Trial 1 and 2 showed excellent discrimination of SIM and HC. All RT indices were less successful in discriminating SIM and TBI. Average RT for Trial 1 and 2 added incremental predictive value to TOMM-C accuracy in distinguishing SIM from TBI. CONCLUSION: Findings contribute to a limited body of research examining the incremental utility of combining RT with traditional PVTs in distinguishing feigned and bona fide TBI. Findings support the hypothesis that combining RT with TOMM-C accuracy can improve its diagnostic accuracy. Future research with other groups of clinical interest is recommended.

Strategies of successful and unsuccessful simulators coached to feign traumatic brain injury.

OBJECTIVE: The present study evaluated strategies used by healthy adults coached to simulate traumatic brain injury (TBI) during neuropsychological evaluation. METHOD: Healthy adults (n = 58) were coached to simulate TBI while completing a test battery consisting of multiple performance validity tests (PVTs), neuropsychological tests, a self-report scale of functional independence, and a debriefing survey about strategies used to feign TBI. RESULTS: "Successful" simulators (n = 16) were classified as participants who failed 0 or 1 PVT and also scored as impaired on one or more neuropsychological index. "Unsuccessful" simulators (n = 42) failed ≥2 PVTs or passed PVTs but did not score impaired on any neuropsychological index. Compared to unsuccessful simulators, successful simulators had significantly more years of education, higher estimated IQ, and were more likely to use information provided about TBI to employ a systematic pattern of performance that targeted specific tests rather than performing poorly across the entire test battery. CONCLUSION: Results contribute to a limited body of research investigating strategies utilized by individuals instructed to feign neurocognitive impairment. Findings signal the importance of developing additional embedded PVTs within standard cognitive tests to assess performance validity throughout a neuropsychological assessment. Future research should consider specifically targeting embedded measures in visual tests sensitive to slowed responding (e.g. response time).

Comparisons of five performance validity indices in bona fide and simulated traumatic brain injury.

A number of performance validity tests (PVTs) are used to assess memory complaints associated with traumatic brain injury (TBI); however, few studies examine the concordance and predictive accuracy of multiple PVTs, specifically in the context of combined models in known-group designs. The present study compared five widely used PVTs: the Test of Memory Malingering (TOMM), Medical Symptom Validity Test (MSVT), Reliable Digit Span (RDS), Word Choice Test (WCT), and California Verbal Learning Test - Forced Choice (CVLT-FC). Participants were 51 adults with bona fide moderate to severe TBI and 58 demographically comparable healthy adults coached to simulate memory impairment. Classification accuracy of individual PVTs was evaluated using logistic regression and receiver operating characteristic (ROC) curves, examining both the dichotomous cutting scores as recommended by the test publishers and continuous scores for the measures. Results demonstrated nearly equivalent discrimination ability of the TOMM, MSVT, and CVLT-FC as individual predictors, all of which markedly outperformed the WCT and RDS. Models of combined PVTs were examined using Bayesian information criterion statistics, with results demonstrating that diagnostic accuracy showed only small to modest growth when the number of tests was increased beyond two. Considering the clinical and pragmatic issues in deriving a parsimonious assessment battery, these findings suggest that using the TOMM and CVLT in conjunction or the MSVT and CVLT in conjunction maximized predictive accuracy as compared to a single index or an assortment of these widely used measures.

Substitution of California Verbal Learning Test, second edition for Verbal Paired Associates on the Wechsler Memory Scale, fourth edition.

Two common measures used to evaluate verbal learning and memory are the Verbal Paired Associates (VPA) subtest from the Wechsler Memory Scales (WMS) and the second edition of the California Verbal Learning Test (CVLT-II). For the fourth edition of the WMS, scores from the CVLT-II can be substituted for VPA; the present study sought to examine the validity of the substitution. For each substitution, paired-samples t tests were conducted between original VPA scaled scores and scaled scores obtained from the CVLT-II substitution to evaluate comparability. Similar comparisons were made at the index score level. At the index score level, substitution resulted in significantly lower scores for the AMI (p = .03; r = .13) but not for the IMI (p = .29) or DMI (p = .09). For the subtest scores, substituted scaled scores for VPA were not significantly different from original scores for the immediate recall condition (p = .20) but were significantly lower at delayed recall (p = .01). These findings offer partial support for the substitution. For both the immediate and delayed conditions, the substitution produced generally lower subtest scores compared to original VPA subtest scores.

Detection of insufficient effort using the advanced clinical solutions for the Wechsler Memory Scale, fourth edition.

This study investigated the ability of the Wechsler Memory Scale-4th Edition (WMS-IV) and the Advanced Clinical Solutions (ACS) package including the new Word Choice test (WCT) to distinguish poor performance due to intentional response bias among simulators of traumatic brain injury (TBI) from poor performance due to actual TBI. Participants were 45 survivors of moderate to severe TBI and 39 healthy adult coached to simulate TBI. Logistic regression indicated that a five-variable model containing all the ACS variables and a single-variable model using only the WCT were statistically reliable. Comparing predictive accuracy of each model found that adding the WCT to the ACS increased predictive accuracy. Diagnostic efficiency for the full ACS model was considered "excellent" according to interpretive guidelines.