Introducing the ImPACT-5: An Empirically Derived Multivariate Validity Composite.

OBJECTIVE: To create novel Immediate Post-Concussion and Cognitive Testing (ImPACT)-based embedded validity indicators (EVIs) and to compare the classification accuracy to 4 existing EVIImPACT. METHOD: The ImPACT was administered to 82 male varsity football players during preseason baseline cognitive testing. The classification accuracy of existing EVIImPACT was compared with a newly developed index (ImPACT-5A and B). The ImPACT-5A represents the number of cutoffs failed on the 5 ImPACT composite scores at a liberal cutoff (0.85 specificity); ImPACT-5B is the sum of failures on conservative cutoffs (≥0.90 specificity). RESULTS: ImPACT-5A ≥1 was sensitive (0.81), but not specific (0.49) to invalid performance, consistent with EVIImPACT developed by independent researchers (0.68 sensitivity at 0.73-0.75 specificity). Conversely, ImPACT-5B ≥3 was highly specific (0.98), but insensitive (0.22), similar to Default EVIImPACT (0.04 sensitivity at 1.00 specificity). ImPACT-5A ≥3 or ImPACT-5B ≥2 met forensic standards of specificity (0.91-0.93) at 0.33 to 0.37 sensitivity. Also, the ImPACT-5s had the strongest linear relationship with clinically meaningful levels of invalid performance of existing EVIImPACT. CONCLUSIONS: The ImPACT-5s were superior to the standard EVIImPACT and comparable to existing aftermarket EVIImPACT, with the flexibility to optimize the detection model for either sensitivity or specificity. The wide range of ImPACT-5 cutoffs allows for a more nuanced clinical interpretation.

Performance Validity in Collegiate Football Athletes at Baseline Neurocognitive Testing.

OBJECTIVE: To assess the prevalence of invalid performance on baseline neurocognitive testing using embedded measures within computerized tests and individually administered neuropsychological measures, and to examine the influence of incentive status and performance validity on neuropsychological test scores. SETTING: Sport-related concussion management program at a regionally accredited university. PARTICIPANTS: A total of 83 collegiate football athletes completing their preseason baseline assessment within the University's concussion management program and a control group of 140 nonathlete students. DESIGN: Cross-sectional design based on differential incentive status: motivated to do poorly to return to play more quickly after sustaining a concussion (athletes) versus motivated to do well due to incentivizing performance (students). MAIN MEASURES: Immediate Post-Concussion and Cognitive Testing (ImPACT), performance validity tests, and measures of cognitive ability. RESULTS: Half of the athletes failed at least 1 embedded validity indicator within ImPACT (51.8%), and the traditional neuropsychological tests (49.4%), with large effects for performance validity on cognitive test scores (d: 0.62-1.35), incentive status (athletes vs students; d: 0.36-1.15), and the combination of both factors (d: 1.07-2.20) on measures of attention and processing speed. CONCLUSION: Invalid performance on baseline assessment is common (50%), consistent across instruments (ImPACT or neuropsychological tests) and settings (one-on-one or group administration), increases as a function of incentive status (risk ratios: 1.3-4.0) and results in gross underestimates of the athletes' true ability level, complicating the clinical interpretation of the postinjury evaluation and potentially leading to premature return to play.

Sleep Biomarkers, Health Comorbidities, and Neurocognition in Obstructive Sleep Apnea.

OBJECTIVES: Obstructive sleep apnea (OSA) is associated with cognitive impairment but the relationships between specific biomarkers and neurocognitive domains remain unclear. The present study examined the influence of common health comorbidities on these relationships. Adults with suspected OSA (N=60; 53% male; M age=52 years; SD=14) underwent neuropsychological evaluation before baseline polysomnography (PSG). Apneic syndrome severity, hypoxic strain, and sleep architecture disturbance were assessed through PSG. METHODS: Depression (Center for Epidemiological Studies Depression Scale, CESD), pain, and medical comorbidity (Charlson Comorbidity Index) were measured via questionnaires. Processing speed, attention, vigilance, memory, executive functioning, and motor dexterity were evaluated with cognitive testing. A winnowing approach identified 9 potential moderation models comprised of a correlated PSG variable, comorbid health factor, and cognitive performance. RESULTS: Regression analyses identified one significant moderation model: average blood oxygen saturation (AVO2) and depression predicting recall memory, accounting for 31% of the performance variance, p<.001. Depression was a significant predictor of recall memory, p<.001, but AVO2 was not a significant predictor. The interaction between depression and AVO2 was significant, accounting for an additional 10% of the variance, p<.001. The relationship between low AVO2 and low recall memory performance emerged when depression severity ratings approached a previously established clinical cutoff score (CESD=16). CONCLUSIONS: This study examined sleep biomarkers with specific neurocognitive functions among individuals with suspected OSA. Findings revealed that depression burden uniquely influence this pathophysiological relationship, which may aid clinical management. (JINS, 2018, 28, 864-875).

Health Outcomes of Traumatic Brain Injury Among Refugee Survivors of Torture.

OBJECTIVE: To compare spontaneous reporting of health complaints in a sample of refugee survivors of torture with a history of moderate/severe traumatic brain injury (TBI) with survivors of torture without TBI and analyze the contribution of posttraumatic stress disorder symptoms to health outcomes. PARTICIPANTS: Treatment-seeking refugee survivors of torture with a moderate/severe TBI (n = 85) and a control group (n = 72) of survivors who suffered a physical injury during their persecution but had no history of a head injury. MEASURES: Health outcomes included a self-report of general physical health (scale 1-5), number of medical visits, and a scaled score of the number of health complaints. The Harvard Trauma Questionnaire (HTQ) was used to measure posttraumatic stress disorder. RESULTS: Moderate/severe TBI was associated with more health complaints but not higher HTQ scores. TBI and HTQ scores are independently associated with a greater number of health complaints, and an interaction between TBI and HTQ scores suggests that the relationship between moderate/severe TBI and the number of health complaints strengthened with increased posttraumatic stress disorder symptom severity. CONCLUSIONS: Health complaints may be a common expression of psychological trauma, and service providers should be certain to explore both medical and psychological contributors when assessing refugee survivors of torture.

Cognitive, Sleep-Arousal, Physical, and Affective Domain Scores on the Post-Concussion Symptom Scale: Added Utility in Detecting Symptom Elevations among Student-Athletes with a Remote History of Concussion.

OBJECTIVE: The evaluation of self-reported symptoms is a standard component of concussion assessment and management. Clinicians typically evaluate a total symptom severity score rather than scores corresponding to specific symptom domains (i.e., cognitive, sleep-arousal, physical, and affective symptoms). This study examined (i) whether elevations in specific symptom domains would be missed when interpreting only the total symptom severity score and (ii) if a single symptom domain elevation was more common than having elevated symptoms across multiple domains. METHOD: Adolescent student-athletes (N = 1,008) with concussion history (i.e., ≥6 months since last concussion) completed the Post-Concussion Symptom Scale (PCSS). The PCSS total score and cognitive, sleep-arousal, physical, and affective domain scores were calculated. To determine if symptoms were elevated, scores were compared to normative data matched on gender and pre-existing conditions, with scores considered elevated if they were ≥84th percentile. The frequency of total and domain score elevations were calculated and stratified by gender and number of prior concussions (i.e., 1 or ≥2 prior concussions). RESULTS: Overall, 26% of student-athletes had an elevated symptom domain score without being elevated on the total score. The most common symptom presentation was to have a single elevated symptom domain (21%), followed by two (11%), three (8%), or four elevated domains (6%). CONCLUSIONS: Interpreting PCSS symptom domains may be beneficial in detecting student-athletes with elevated symptoms following a remote concussion. Roughly a quarter of student-athletes have domain-specific symptom elevations that would be missed by interpreting the total score alone.

Multivariate models provide an effective psychometric solution to the variability in classification accuracy of D-KEFS Stroop performance validity cutoffs.

ObjectiveThe study was designed to expand on the results of previous investigations on the D-KEFS Stroop as a performance validity test (PVT), which produced diverging conclusions. Method The classification accuracy of previously proposed validity cutoffs on the D-KEFS Stroop was computed against four different criterion PVTs in two independent samples: patients with uncomplicated mild TBI (n = 68) and disability benefit applicants (n = 49). Results Age-corrected scaled scores (ACSSs) ≤6 on individual subtests often fell short of specificity standards. Making the cutoffs more conservative improved specificity, but at a significant cost to sensitivity. In contrast, multivariate models (≥3 failures at ACSS ≤6 or ≥2 failures at ACSS ≤5 on the four subtests) produced good combinations of sensitivity (.39-.79) and specificity (.85-1.00), correctly classifying 74.6-90.6% of the sample. A novel validity scale, the D-KEFS Stroop Index correctly classified between 78.7% and 93.3% of the sample. Conclusions A multivariate approach to performance validity assessment provides a methodological safeguard against sample- and instrument-specific fluctuations in classification accuracy, strikes a reasonable balance between sensitivity and specificity, and mitigates the invalid before impaired paradox.

Replicating a Meta-Analysis: The Search for the Optimal Word Choice Test Cutoff Continues.

This study was designed to expand on a recent meta-analysis that identified ≤42 as the optimal cutoff on the Word Choice Test (WCT). We examined the base rate of failure and the classification accuracy of various WCT cutoffs in four independent clinical samples (N = 252) against various psychometrically defined criterion groups. WCT ≤ 47 achieved acceptable combinations of specificity (.86-.89) at .49 to .54 sensitivity. Lowering the cutoff to ≤45 improved specificity (.91-.98) at a reasonable cost to sensitivity (.39-.50). Making the cutoff even more conservative (≤42) disproportionately sacrificed sensitivity (.30-.38) for specificity (.98-1.00), while still classifying 26.7% of patients with genuine and severe deficits as non-credible. Critical item (.23-.45 sensitivity at .89-1.00 specificity) and time-to-completion cutoffs (.48-.71 sensitivity at .87-.96 specificity) were effective alternative/complementary detection methods. Although WCT ≤ 45 produced the best overall classification accuracy, scores in the 43 to 47 range provide comparable objective psychometric evidence of non-credible responding. Results question the need for designating a single cutoff as "optimal," given the heterogeneity of signal detection environments in which individual assessors operate. As meta-analyses often fail to replicate, ongoing research is needed on the classification accuracy of various WCT cutoffs.

The Post-Concussion Symptom Scale: Normative Data for Adolescent Student-Athletes Stratified by Gender and Preexisting Conditions.

BACKGROUND: The Post-Concussion Symptom Scale (PCSS) is a self-report questionnaire measuring symptoms that commonly occur after a concussion; however, these symptoms are nonspecific and can be related to co-occurring orthopaedic injuries (eg, cervical strain) or patient characteristics and preexisting conditions, even in the absence of a recent injury. As such, clinicians may have difficulty determining whether symptom elevations are attributable to a recent concussion as opposed to a confounding injury or a preexisting condition, which may be especially difficult when preinjury baseline symptom data are unavailable. PURPOSE: This study aimed to further validate the 4-factor model of the PCSS (ie, cognitive, sleep-arousal, physical, and affective symptoms) with adolescent student-athletes and provide normative reference data for each factor and the total score, stratified by gender and preexisting health conditions. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Participants were 9358 adolescent student-athletes who completed the PCSS during a preseason baseline evaluation (mean age, 14.9 years; SD, 1.3 years [range, 13-18 years]; 49.3% boys). The 4-factor model of the PCSS was tested for the full sample and separately for boys and girls using confirmatory factor analysis. Symptom severity percentiles were created for the PCSS total score and each factor, stratified by gender and preexisting conditions (ie, attention-deficit/hyperactivity disorder, mental health history, headache/migraine history, learning disability/dyslexia, academic problems, and concussion history). RESULTS: The 4-factor model of the PCSS replicated in the full sample (comparative fit index [CFI] = 0.959) and in both gender groups (boys: CFI = 0.961; girls: CFI = 0.960). The total PCSS score at the 84th percentile varied by preexisting conditions as follows: healthy participants = 8, attention-deficit/hyperactivity disorder = 18, mental health history = 26, headache/migraine history = 18, learning disability = 19, and academic problems = 17. On all PCSS subscales, participants with a mental health history had the highest scores, and high scores were associated with having >1 preexisting condition. Girls had higher scores than boys for each stratification. CONCLUSION: The 4-factor model of the PCSS replicates for adolescent student-athletes. Gender, number of preexisting conditions, and mental health history are important factors to account for when interpreting PCSS symptom severity. The normative data provided herein could assist clinicians in determining whether an adolescent student-athlete is presenting with persistent postconcussion symptoms or a typical symptom experience based on their gender and personal health history.

Inconsistent vs consistent right-handers' performance on an episodic memory task: evidence from the California Verbal Learning Test.

Inconsistent handedness is associated with better memory performance on episodic memory tasks than consistent handedness. The present study further explored this difference in memory related to handedness by administering a measure that is used in clinical settings to assess different aspects of long-term memory. The results indicated that inconsistent right-handed individuals recalled and recognised more words on the California Verbal Learning Test-II than consistent right-handed individuals. Inconsistent right-handers also showed better performance than consistent right-handers on measures of source recognition. The results of this study further extend the effects of handedness on memory to the clinical setting because the CVLT-II is a measure used extensively in clinical neuropsychology.

An updated review of the prevalence of invalid performance on the Immediate Post-Concussion and Cognitive Testing (ImPACT).

Objective: Performance validity assessment is an important component of concussion baseline testing and Immediate Post-Concussion and Cognitive Testing (ImPACT) is the most commonly used test in this setting. A review of invalid performance on ImPACT was published in 2017, focusing largely on the default embedded validity indicator (Default EVI) provided within the test. There has since been a proliferation in research evaluating the classification accuracy of the Default EVI against independently developed, alternative ImPACT-based EVIs, necessitating an updated review. The purpose of this study was to provide an up-to-date review of the prevalence of invalid performance on ImPACT and to examine the relative effectiveness of ImPACT-based EVIs. Method: Literature related to the prevalence of invalid performance on ImPACT and the effectiveness of ImPACT-based EVIs, published between January 2000 and May 2020, was critically reviewed. Results: A total of 23 studies reported prevalence of invalid performance at baseline testing using ImPACT. Six percent of baseline assessments were found to be invalid by the ImPACT's Default EVI, and between 22.31% and 34.99% were flagged by alternative EVIs. Six studies assessed the effectiveness of ImPACT-based EVIs, with the Default EVI correctly identifying experimental malingerers only 60% of the time. Alternative ImPACT-based EVIs identified between 73% and 100% of experimental malingerers. Conclusions: The ImPACT's Default EVI is not sufficiently sensitive, and clinicians should consider alternative indicators when assessing invalid performance. Accordingly, the base rate of invalid performance in athletes at baseline testing is likely well above the 6% previously reported.

Cross-Cultural Performance Validity Testing: Managing False Positives in Examinees with Limited English Proficiency.

Base rates of failure (BRFail) on performance validity tests (PVTs) were examined in university students with limited English proficiency (LEP). BRFail was calculated for several free-standing and embedded PVTs. All free-standing PVTs and certain embedded indicators were robust to LEP. However, LEP was associated with unacceptably high BRFail (20-50%) on several embedded PVTs with high levels of verbal mediation (even multivariate models of PVT could not contain BRFail). In conclusion, failing free-standing/dedicated PVTs cannot be attributed to LEP. However, the elevated BRFail on several embedded PVTs in university students suggest an unacceptably high overall risk of false positives associated with LEP.

Failing Performance Validity Cutoffs on the Boston Naming Test (BNT) Is Specific, but Insensitive to Non-Credible Responding.

This study was designed to examine alternative validity cutoffs on the Boston Naming Test (BNT).Archival data were collected from 206 adults assessed in a medicolegal setting following a motor vehicle collision. Classification accuracy was evaluated against three criterion PVTs.The first cutoff to achieve minimum specificity (.87-.88) was T ≤ 35, at .33-.45 sensitivity. T ≤ 33 improved specificity (.92-.93) at .24-.34 sensitivity. BNT validity cutoffs correctly classified 67-85% of the sample. Failing the BNT was unrelated to self-reported emotional distress. Although constrained by its low sensitivity, the BNT remains a useful embedded PVT.

This will only take a minute: Time cutoffs are superior to accuracy cutoffs on the forced choice recognition trial of the Hopkins Verbal Learning Test - Revised.

OBJECTIVE: This study was designed to evaluate the classification accuracy of the recently introduced forced-choice recognition trial to the Hopkins Verbal Learning Test - Revised (FCRHVLT-R) as a performance validity test (PVT) in a clinical sample. Time-to-completion (T2C) for FCRHVLT-R was also examined. METHOD: Forty-three students were assigned to either the control or the experimental malingering (expMAL) condition. Archival data were collected from 52 adults clinically referred for neuropsychological assessment. Invalid performance was defined using expMAL status, two free-standing PVTs and two validity composites. RESULTS: Among students, FCRHVLT-R ≤11 or T2C ≥45 seconds was specific (0.86-0.93) to invalid performance. Among patients, an FCRHVLT-R ≤11 was specific (0.94-1.00), but relatively insensitive (0.38-0.60) to non-credible responding0. T2C ≥35 s produced notably higher sensitivity (0.71-0.89), but variable specificity (0.83-0.96). The T2C achieved superior overall correct classification (81-86%) compared to the accuracy score (68-77%). The FCRHVLT-R provided incremental utility in performance validity assessment compared to previously introduced validity cutoffs on Recognition Discrimination. CONCLUSIONS: Combined with T2C, the FCRHVLT-R has the potential to function as a quick, inexpensive and effective embedded PVT. The time-cutoff effectively attenuated the low ceiling of the accuracy scores, increasing sensitivity by 19%. Replication in larger and more geographically and demographically diverse samples is needed before the FCRHVLT-R can be endorsed for routine clinical application.

The emotion word fluency test as an embedded performance validity indicator - Alone and in a multivariate validity composite.

OBJECTIVE: This project was designed to cross-validate existing performance validity cutoffs embedded within measures of verbal fluency (FAS and animals) and develop new ones for the Emotion Word Fluency Test (EWFT), a novel measure of category fluency. METHOD: The classification accuracy of the verbal fluency tests was examined in two samples (70 cognitively healthy university students and 52 clinical patients) against psychometrically defined criterion measures. RESULTS: A demographically adjusted T-score of ≤31 on the FAS was specific (.88-.97) to noncredible responding in both samples. Animals T ≤ 29 achieved high specificity (.90-.93) among students at .27-.38 sensitivity. A more conservative cutoff (T ≤ 27) was needed in the patient sample for a similar combination of sensitivity (.24-.45) and specificity (.87-.93). An EWFT raw score ≤5 was highly specific (.94-.97) but insensitive (.10-.18) to invalid performance. Failing multiple cutoffs improved specificity (.90-1.00) at variable sensitivity (.19-.45). CONCLUSIONS: Results help resolve the inconsistency in previous reports, and confirm the overall utility of existing verbal fluency tests as embedded validity indicators. Multivariate models of performance validity assessment are superior to single indicators. The clinical utility and limitations of the EWFT as a novel measure are discussed.

Affective and cognitive correlates of gambling behavior in university students.

The purpose of the following study was to explore certain affective and cognitive components and their relationships to gambling behavior in an undergraduate population. Specifically, the aim was to predict gambling severity using depression scores on the BDI-II, the dependency and self-criticism subscales on the DEQ, emotional awareness scores on the LEAS, cognitive flexibility scores from the STROOP, and a creativity subtests from the TTCT. Participants were 200 undergraduate students and 3.5-7.5% of individuals reported some level of problematic gambling behavior. Multiple regression analysis indicated that self-criticism and creative originality were significant predictors of gambling behavior, explaining 7.6% of the variance. Further analyses reveal a non-linear trend in the creative originality of those who gamble; only the at-risk gamblers were high in creativity whereas abstainers and problematic gamblers display similarly lower levels of creativity. Results are discussed in regards to Blaszczynski and Nower's Addiction 97:487-499 (2002) subtypes of gambling vulnerability.

The V-5 provides quick, accurate and cross-culturally valid measures of psychiatric symptoms.

This study was designed to cross-validate the V-5, a quick psychiatric screener, across administration formats and levels of examinee acculturation. The V-5 was administered twice (once at the beginning and once at the end of the testing session) to three samples (N = 277) with varying levels of symptom severity and English language proficiency, varying type of administration, alongside traditional self-reported symptom inventories as criterion measures. The highest rest-retest reliability was observed on the Depression (.84) and Pain scales (.85). The V-5 was sensitive to the variability in symptom severity. Classification accuracy was driven by the base rate of the target construct, and was invariant across administration format (in-person or online) or level of English proficiency. The V-5 demonstrated promise as a cross-culturally robust screening instrument that is sensitive to change over time, lends itself to online administration, and is suitable for examinees with limited English proficiency.

Introducing a forced choice recognition trial to the Hopkins Verbal Learning Test - Revised.

OBJECTIVE: This study was designed to replicate previous research on embedded validity indicators (EVIs) in the Hopkins Verbal Learning Test - Revised (HVLT-R) and introduce a new forced choice recognition trial (FCR). METHOD: Undergraduate research volunteers were randomly assigned (MAge = 21.7; MEducation = 14.5 years, 85% female) to either the control or experimental malingering condition, and were administered a brief battery of neuropsychological tests. RESULTS: Recognition memory based EVIs (both existing and newly introduced) effectively discriminated credible and non-credible response sets. An FCR ≤11 produced .59 sensitivity and perfect specificity to invalid responding. A Recognition Discrimination (RD) score ≤8 also produced a good combination of sensitivity (.35) and specificity (.96). The FCR trial made unique contributions to performance validity assessment above and beyond previously published EVIs. CONCLUSIONS: RD achieved ≥.90 specificity at higher cutoffs than previously reported. The newly introduced FCR trial has the potential to enhance the existing arsenal of EVIs within the HVLT-R. However, it must demonstrate its ability to differentiate genuine impairment from non-credible responding before it can be recommended for clinical use.

Development of embedded performance validity indicators in the NIH Toolbox Cognitive Battery.

To assess noncredible performance on the NIH Toolbox Cognitive Battery (NIHTB-CB), we developed embedded validity indicators (EVIs). Data were collected from 98 adults (54.1% female) as part of a prospective multicenter cross-sectional study at 4 mild traumatic brain injury (mTBI) specialty clinics. Traditional EVIs and novel item-based EVIs were developed for the NIHTB-CB using the Medical Symptom Validity Test (MSVT) as criterion. The signal detection profile of individual EVIs varied greatly. Multivariate models had superior classification accuracy. Failing ≥4 traditional EVIs at the liberal cutoff or ≥3 at the conservative cutoff produced a good combination of sensitivity (.57 to .61) and specificity (.92 to .94) to MSVT. Combining the traditional and item-based EVIs improved sensitivity (.65 to .70) at comparable specificity (.91 to .95). In conclusion, newly developed EVIs within the NIHTB-CB effectively discriminated between patients who passed versus failed the MSVT. Aggregating EVIs within the same category into validity composites improved signal detection over univariate cutoffs. Item-based EVIs improved classification accuracy over that of traditional EVIs. However, the marginal gains hardly justify the burden of extra calculations. The newly introduced EVIs require cross-validation before wide-spread research or clinical application. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Degree versus direction: a comparison of four handedness classification schemes through the investigation of lateralised semantic priming.

Four classification systems were examined using lateralised semantic priming in order to investigate whether degree or direction of handedness better captures the pattern of lateralised semantic priming. A total of 85 participants completed a lateralised semantic priming task and three handedness questionnaires. The classification systems tested were: (1) the traditional right- vs left-handed (RHs vs LHs); (2) a four-factor model of strong and weak right- and left-handers (SRHs, WRHs, SLHs, WLHs); (3) strong- vs mixed-handed (SHs vs MHs); and (4) a three-factor model of consistent left- (CLHs), inconsistent left- (ILHs), and consistent right-handers (CRHs). Mixed-factorial ANOVAs demonstrated significant visual field (VF) by handedness interactions for all but the third model. Results show that LHs, SLHs, CLHs, and ILHs responded faster to LVF targets, whereas RHs, SRHs, and CRHs responded faster to RVF targets; no significant VF by handedness interaction was found between SHs and MHs. The three-factor model better captures handedness group divergence on lateralised semantic priming by incorporating the direction of handedness as well as the degree. These findings help explain some of the variance in language lateralisation, demonstrating that direction of handedness is as important as degree. The need for greater consideration of handedness subgroups in laterality research is highlighted.

Stronger Together: The Wechsler Adult Intelligence Scale-Fourth Edition as a Multivariate Performance Validity Test in Patients with Traumatic Brain Injury.

OBJECTIVE: This study was designed to evaluate the classification accuracy of a multivariate model of performance validity assessment using embedded validity indicators (EVIs) within the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). METHOD: Archival data were collected from 100 adults with traumatic brain injury (TBI) consecutively referred for neuropsychological assessment in a clinical setting. The classification accuracy of previously published individual EVIs nested within the WAIS-IV and a composite measure based on six independent EVIs were evaluated against psychometrically defined non-credible performance. RESULTS: Univariate validity cutoffs based on age-corrected scaled scores on Coding, Symbol Search, Digit Span, Letter-Number-Sequencing, Vocabulary minus Digit Span, and Coding minus Symbol Search were strong predictors of psychometrically defined non-credible responding. Failing ≥3 of these six EVIs at the liberal cutoff improved specificity (.91-.95) over univariate cutoffs (.78-.93). Conversely, failing ≥2 EVIs at the more conservative cutoff increased and stabilized sensitivity (.43-.67) compared to univariate cutoffs (.11-.63) while maintaining consistently high specificity (.93-.95). CONCLUSIONS: In addition to being a widely used test of cognitive functioning, the WAIS-IV can also function as a measure of performance validity. Consistent with previous research, combining information from multiple EVIs enhanced the classification accuracy of individual cutoffs and provided more stable parameter estimates. If the current findings are replicated in larger, diagnostically and demographically heterogeneous samples, the WAIS-IV has the potential to become a powerful multivariate model of performance validity assessment. BRIEF SUMMARY: Using a combination of multiple performance validity indicators embedded within the subtests of theWechsler Adult Intelligence Scale, the credibility of the response set can be establishedwith a high level of confidence. Multivariatemodels improve classification accuracy over individual tests. Relying on existing test data is a cost-effective approach to performance validity assessment.