Forensic neuropsychological assessment.

With its firm establishment as a neuropsychology subspecialty, forensic neuropsychological assessment is integral to many criminal and civil forensic evaluations. In addition to evaluating cognitive deficits, forensic neuropsychologists can provide reliable information regarding symptom magnification, malingering, and other neurocognitive and psychological issues that may impact the outcome of a particular legal case. This article is an overview and introduction to neuropsychological assessment in the forensic mental health context. Major issues impacting the current practice of forensic neuropsychology are summarized, and several examples from case law are highlighted.

Forensic assessment of somatoform and functional neurological disorders.

Functional neurological disorders (FND) and somatization are common in clinical practice and medicolegal settings. These conditions are frequently disabling and, if arising following an accident, may lead to claims for legal compensation or occupational disability (such as social security disability insurance). However, distinguishing FND and somatization from symptoms that are intentionally produced (i.e., malingered or factitious) may pose a major forensic psychiatric challenge. In this article, we describe how somatoform disorders and FND lie along a spectrum of abnormal illness-related behaviors, including factitious disorder, compensation neurosis, and malingering. We provide a systematic approach to the forensic assessment of FND and conclude by describing common litigation scenarios in which FND may be at issue. Forensic testimony may play an important role in the resolution of such cases.

Importance of validity testing in psychiatric assessment: evidence from a sample of multimorbid post-9/11 veterans.

OBJECTIVE: Performance validity (PVTs) and symptom validity tests (SVTs) are necessary components of neuropsychological testing to identify suboptimal performances and response bias that may impact diagnosis and treatment. The current study examined the clinical and functional characteristics of veterans who failed PVTs and the relationship between PVT and SVT failures. METHOD: Five hundred and sixteen post-9/11 veterans participated in clinical interviews, neuropsychological testing, and several validity measures. RESULTS: Veterans who failed 2+ PVTs performed significantly worse than veterans who failed one PVT in verbal memory (Cohen's d = .60-.69), processing speed (Cohen's d = .68), working memory (Cohen's d = .98), and visual memory (Cohen's d = .88-1.10). Individuals with 2+ PVT failures had greater posttraumatic stress (PTS; ß = 0.16; p = .0002), and worse self-reported depression (ß = 0.17; p = .0001), anxiety (ß = 0.15; p = .0007), sleep (ß = 0.10; p = .0233), and functional outcomes (ß = 0.15; p = .0009) compared to veterans who passed PVTs. 7.8% veterans failed the SVT (Validity-10; ≥19 cutoff); Multiple PVT failures were significantly associated with Validity-10 failure at the ≥19 and ≥23 cutoffs (p's < .0012). The Validity-10 had moderate correspondence in predicting 2+ PVTs failures (AUC = 0.83; 95% CI = 0.76, 0.91). CONCLUSION: PVT failures are associated with psychiatric factors, but not traumatic brain injury (TBI). PVT failures predict SVT failure and vice versa. Standard care should include SVTs and PVTs in all clinical assessments, not just neuropsychological assessments, particularly in clinically complex populations.

Distinguishing clinical and simulated dissociative identity disorder using the Miller Forensic Assessment of Symptoms Test.

BACKGROUND: Individuals with dissociative identity disorder (DID) experience severe and broad-ranging symptoms which can be associated with elevations on measures designed to detect feigning and/or malingering. Research is needed to determine how to distinguish genuine DID from simulated DID on assessment measures and validity scales. OBJECTIVE: This study examined whether the Miller Forensic Assessment of Symptoms Test (M-FAST), a screening measure of malingering, could differentiate between individuals with DID and DID simulators. METHOD: Thirty-five individuals with clinical, validated DID were compared to 88 individuals attempting to simulate DID on the M-FAST. A MANCOVA compared the two groups on total M-FAST score and subscales. Univariate ANCOVA's examined differences between the groups. A series of logistic regressions were conducted to determine whether group status predicted the classification of malingering. Utility statistics evaluated how well the M-FAST discerned clinical and simulated DID. RESULTS: The M-FAST correctly classified 82.9% of individuals with DID as not malingering when using the suggested cut-off score of six. However, utilizing a cut-off score of seven correctly classified 93.6% of all participants and maintained adequate sensitivity (.96) but demonstrated increased specificity (.89). CONCLUSIONS: The M-FAST shows promise in distinguishing genuine DID when the cut-off score is increased to seven. This study adds to the growing body of literature identifying tests that can adequately distinguish clinical from simulated DID. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Performance and symptom validity assessment in attention deficit/hyperactivity disorder: Base rates of invalidity, concordance, and relative impact on cognitive performance.

Objective: Differential diagnosis of attention deficit/hyperactivity disorder (ADHD) is one of the most common referral questions for neuropsychological evaluation but is complicated by the presence of external incentives. Validity assessment is therefore critical in such evaluations, employing symptom validity tests (SVTs) and performance validity tests (PVTs) to assess the validity of reported symptoms and cognitive test performance, respectively. This study aimed to establish the base rate of symptom and performance invalidity in adults referred for ADHD, compare concordance between performance and symptom validity, and assess the impact of each type of validity on cognitive test performance. Method: This consecutive case series included data from 392 demographically-diverse adults who underwent outpatient neuropsychological evaluation for ADHD. All patients were administered the Clinical Assessment of Attention Deficit-Adult (CAT-A) and a uniform cognitive test battery, including seven PVTs. Results: Invalid symptom reporting and PVT performance were found in 22% and 16% of the sample, respectively. Sixty-eight percent had concordantly valid SVTs/PVTs and 6% had invalid SVTs/PVTs, whereas the remaining 26% had either invalid SVTs or PVTs (but not both). Invalid PVT performance resulted in a significant decrease across all cognitive test scores, with generally large effects (ηp2=.01-.18). Invalid symptom reporting had minimal effects on cognitive test performance (ηp2= ≤.04). Conclusions: PVTs and SVTs are dissociable and therefore should not be used interchangeably in the context of adult ADHD evaluations. Rather, symptom and performance validity should continue to be assessed independently as they provide largely non-redundant information.

Structured Interview of Reported Symptoms-2nd Edition (SIRS-2): Use and Admissibility in Forensic Mental Health Assessment.

Assessment of symptom feigning is paramount in forensic psychological and psychiatric assessment. The Structured Interview of Reported Symptoms, 2nd Edition (SIRS-2; Rogers et al., 2010) is a revised edition to the original SIRS (Rogers et al., Structured Interview of Reported Symptoms (SIRS) and professional manual. Psychological Assessment Resources, Inc, 1992) and was developed to assess feigned psychiatric symptoms. The current paper reviews use of the SIRS-2 in forensic assessment, specifically addressing topics such as translations of the instrument, its use in assessing psychiatric and cognitive feigning, and its use in special populations. Empirical foundation and psychometric properties of the SIRS-2 is also covered. The SIRS-2 was revised in part to reduce false positive classifications of feigning. Research suggests that this goal was largely accomplished, albeit at the expense of reduced sensitivity. The paper also provides a review of federal and state appellate cases that mention the SIRS-2. Notably, most cases that cite the SIRS-2 do not actually center on the SIRS-2, and the test's admissibility has never been outrightly challenged. The paper concludes with a discussion of expert testimony concerning the SIRS-2.

Evaluation of Various Detection Strategies in the Assessment of Noncredible Memory Performance: Results of Two Experimental Studies.

OBJECTIVE: This article investigates the accuracy of individual and combined indicators based on different strategies for detecting noncredible performance as part of a new test for the continuous assessment of short-term memory. METHOD: In two independent studies, we assessed three groups of simulators, cognitively impaired patients, and nonimpaired community members with four tasks separated by a distractor. RESULTS: Pairwise comparisons between receiver operating characteristic (ROC) curves revealed significant differences between two clusters of indicators: mean recognition, inconsistent responses in recognition, and false positives (area under the ROC curves > .800) proved more accurate than delayed recall and false negatives (area under the ROC curves < .800) in discriminating simulators from patients. Likewise, both studies revealed that adding the false positives indicator based on cued recall to mean recognition incrementally improved classification accuracy (including sensitivity, positive predictive value, and negative predictive value ) compared with the recognition indicator alone. CONCLUSIONS: Our results support the association of two distinct indicators for the assessment of noncredible performance, of which one should be a forced-choice indicator.

[Validity of the "Structured Inventory of Malingered Symptomatology" [SIMS] in the Assessment of Healthy Individuals and Patients with Psychiatric Disorders Outside the Forensic Context]. / Validität des "Strukturierten Fragebogens Simulierter Symptome" [SIMS] bei gesunden Probanden und Patienten mit psychiatrischen Erkrankungen außerhalb eines forensischen Kontexts.

OBJECTIVE: Assessment of the rate of false-positive results of the Structured Inventory of Malingered Symptomatology (SIMS) in healthy controls and authentic patients outside the forensic or rehabilitative context. METHODS: Beyond the SIMS scores, further variables (PANSS, Hamilton scale, MMSE) were obtained. SIMS scores of healthy individuals were compared with the SIMS scores of the different groups of patients. Additionally, correlations between the SIMS scores and other variables were investigated. RESULTS: Patients with psychotic disorders (n=30) or depressive episodes (n=32) more frequently achieved SIMS scores >16 as compared to healthy controls. In comparison, patients with amnestic disorders (n=15) had inconspicuous SIMS scores. Depressed patients with positive SIMS results were significantly more likely to be diagnosed with another psychiatric disorder and the scores of these patients on the Hamilton scale were correlated with positive results on 2 subscales of the SIMS (NI, AF). CONCLUSION: If this instrument is to applied in clinical practice in the future, further validation of the SIMS is necessary. The specificity of the SIMS seems to be context-related.

Discriminating malingered attention Deficit Hyperactivity Disorder from genuine symptom reporting using novel Personality Assessment Inventory validity measures.

It is now widely understood that ADHD can be feigned easily and convincingly. Despite this, almost no methods exist to assist clinicians in identifying when such behavior occurs. Recently, new validity indicators specific to feigned ADHD were reported for the Personality Assessment Inventory (PAI). Derived from a logistic regression, these algorithms are said to have excellent specificity and good sensitivity in identifying feigned ADHD. However, these authors compared those with genuine ADHD only to nonclinical undergraduate students (asked to respond honestly or asked to simulate ADHD); no criterion group of definite malingerers was included. We therefore investigated these new validity indicators with 331 postsecondary students who underwent assessment for possible ADHD and compared scores of those who were eventually diagnosed with ADHD (n = 111) to those who were not [Clinical controls (66), Definite malingerers (36); No diagnosis (117)]. The two proposed PAI algorithms were found to have poor positive predictive value (.19 and .17). Self-report validity measures from the Connors' Adult Attention Rating Scale, and the Negative Impression Management scale on the PAI returned more positive results. Overall, more research is needed to better identify noncredible ADHD presentation, as the PAI-based methods proposed by Aita et al. appear inadequate as symptom validity measures.

The Divergent Roles of Symptom and Performance Validity in the Assessment of ADHD.

OBJECTIVE: This study examined concordance between symptom and performance validity among clinically-referred patients undergoing neuropsychological evaluation for Attention-Deficit/Hyperactivity Disorder (ADHD). METHOD: Data from 203 patients who completed the WAIS-IV Working Memory Index, the Clinical Assessment of Attention Deficit-Adult (CAT-A), and ≥4 criterion performance validity tests (PVTs) were analyzed. RESULTS: Symptom and performance validity were concordant in 76% of cases, with the majority being valid performance. Of the remaining 24% of cases with divergent validity findings, patients were more likely to exhibit symptom invalidity (15%) than performance invalidity (9%). Patients demonstrating symptom invalidity endorsed significantly more ADHD symptoms than those with credible symptom reporting (ηp2 = .06-.15), but comparable working memory test performance, whereas patients with performance invalidity had significantly worse working memory performance than those with valid PVT performance (ηp2 = .18). CONCLUSION: Symptom and performance invalidity represent dissociable constructs in patients undergoing neuropsychological evaluation of ADHD and should be evaluated independently.

The relationship of cogniphobia to performance validity and symptom validity in neuropsychological assessment.

OBJECTIVE: Emerging research suggests that fear and avoidance are associated with not only physical symptoms, but also cognitive functioning. The concept of cogniphobia describes the fear and avoidance of cognitively effortful tasks to avoid the onset or worsening of symptoms. Extant studies provide preliminary evidence for associations between cogniphobia and validity testing. However, less is known about the subcomponents of cogniphobia. This study investigated the relationship of cogniphobia subcomponents to validity testing and psychological presentations. METHOD: Participants included 171 adults from an archival database who had completed measures of cogniphobia and psychological symptom reports as part of a larger neuropsychological study. The sample was classified as scoring above or below published cutoffs on performance validity tests (PVTs) and symptom validity tests (SVTs), consistent with current research/recommendations. RESULTS: Confirmatory factor analysis (CFA) supported a two-factor model of cogniphobia, with Avoidance and Dangerousness as subcomponents. Logistic regression analyses identified Avoidance as the strongest predictor of scores falling in the invalid range on PVTs and SVTs, as well as the presence of external incentives. After excluding participants who fell in the invalid range on SVTs, only Avoidance significantly predicted report of somatic complaints. CONCLUSIONS: Cogniphobia, especially the avoidance of cognitive exertion component, is associated with performance in the invalid range on both PVTs and SVTs and is also related to report of somatic concerns when controlling for beliefs that cognitive exertion is dangerous. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Delayed matching to sample task 48: assessment of malingering with simulating design.

The results of neuropsychological tests may be distorted by patients who exaggerate cognitive deficits. Eighty-three patients with cognitive deficit [Amnestic Mild Cognitive Impairment (aMCI), n = 53; Alzheimer's disease (AD) dementia, n = 30], 44 healthy older adults (HA), and 30 simulators of AD (s-AD) underwent comprehensive neuropsychological assessment. Receiver Operating Characteristic (ROC) analysis revealed high specificity but low sensitivity of the Delayed Matching to Sample Task (DMS48) in differentiating s-AD from AD dementia (87 and 53%, respectively) and from aMCI (96 and 57%). The sensitivity was considerably increased by using the DMS48/Rey Auditory Verbal Learning Test (RAVLT) ratio (specificity and sensitivity 93% and 93% for AD dementia and 96% and 80% for aMCI). The DMS48 differentiates s-AD from both aMCI and AD dementia with high specificity but low sensitivity. Its predictive value greatly increased when evaluated together with the RAVLT.

Contribution of the neuropsychological assessment in concussion.

INTRODUCTION: The neuropsychological assessment is a cornerstone in the care management of concussion or mild traumatic injury. OBJECTIVE: To present the different stages of an exhaustive neuropsychological assessment exploring cognitive and behavioral domains. METHOD: Description of the value of the main tests available for behavioral and cognitive assessment. The choice of tests is based on the clinical experience and expertise of the authors. RESULTS: Questionnaires are mainly used to explore the behavioral sequelae (depression, anxiety or fatigue) and the impact of these potential difficulties in daily life. Four cognitive abilities could be impaired by concussion: attention, memory, visuospatial functions and executive functions. These abilities could be explored with "paper and pencil" tests or with computerized test batteries. While cognitive sequelae in the context of a moderate or a severe traumatic brain injury are consolidated, in the context of concussion, neuropsychological sequelae tend to resolve in a short time. As a consequence, several neuropsychological assessments could be conducting in a short period involving some methodological considerations. Moreover, as concussion could be reported in a Whiplash injury from a car crash with forensic consequences, it is crucial to propose tests to be sure that the weak performance obtained into the neuropsychological assessment is not explained by poor effort and/or malingering. DISCUSSION/CONCLUSION: This article revises these aspects of a neuropsychological assessment in the specific context of concussion.

[Response distortion or symptom severity? Symptom description by psychiatric patients and sociomedical assessment subjects]. / Antwortverzerrung oder Symptombelastung? Beschwerdeschilderung von psychiatrischen Patienten und sozialmedizinischen Begutachtungsprobanden.

BACKGROUND: Psychiatric disorders are the most frequent cause for premature retirement; however, trying to verify claims of performance deficits due to psychiatric disorders without the actual existence of the latter in sociomedical assessments is problematic. For this reason, differentiation between actual psychiatric disorders with real presence of symptoms and simulated or aggravated symptoms is of importance in sociomedical assessments. In recent years, symptom validity tests (SVT) have been increasingly utilized in psychiatric/psychological assessments; however, knowledge of the validity of these tests and the relation to symptom severity is still lacking. OBJECTIVE: This study aimed to compare the validity of different SVTs depending on symptom severity (Structured Inventory of Malingered Symptomatology (SIMS), Word Memory Test (WMT), Symptom Checklist-90-R (SCL-90­R), Minnesota Multiphasic Personality Inventory­2 (MMPI-2)). MATERIAL AND METHODS: Clinically treated inpatient psychiatric patients (n = 30) were compared with subjects of sociomedical assessments (n = 29) regarding their tendency to simulate or aggravate symptoms. RESULTS: It could be shown that the WMT and the SIMS both failed in the differentiation between psychiatric patients and subjects of sociomedical assessments, regarding description of symptoms or (un)restricted performance motivation. Furthermore, 20% of psychiatric patients were classified as false positive in WMT. The results of the SIMS were significantly related to the severity of psychiatric symptoms in SCL-90­R, therefore the severity of symptoms was assessed rather than the response distortion. CONCLUSION: The results underline the importance of further research on SVTs in sociomedical assessments, especially regarding symptom severity and response distortion.

Specificity and item endorsement rates of personality assessment inventory over-reporting scales across ethnic, gender, and diagnostic groups in a forensic inpatient sample.

The accurate evaluation of response style, particularly with respect to overreporting, is imperative in forensic settings wherein an external incentive to feign exists. Given the high cost of false positive errors in this context, as well as the associated cost of false negative errors, evaluators need to ensure that overreporting methods are effective with the unique patient populations with whom they work. Complicating this issue is that forensic samples often differ in predictable ways from the normative samples upon which typical psychological assessment instruments were normed. The purpose of the present investigation was to evaluate the specificity of the overreporting indices on the Personality Assessment Inventory, one of the most commonly used personality inventories, in a forensic sample with no ostensible incentive to feign. Although item endorsement and configural elevations on the Negative Impression Management (NIM) scale and the Malingering Index (MAL) were associated with genuine psychopathology, results indicated that the overall specificity estimates across groups were generally adequate. Further, and consistent with prior research, Rogers Discriminant Function (RDF) performed poorly in this sample.

Multidimensional Malingering Criteria for Neuropsychological Assessment: A 20-Year Update of the Malingered Neuropsychological Dysfunction Criteria.

OBJECTIVES: Empirically informed neuropsychological opinion is critical for determining whether cognitive deficits and symptoms are legitimate, particularly in settings where there are significant external incentives for successful malingering. The Slick, Sherman, and Iversion (1999) criteria for malingered neurocognitive dysfunction (MND) are considered a major milestone in the field's operationalization of neurocognitive malingering and have strongly influenced the development of malingering detection methods, including serving as the criterion of malingering in the validation of several performance validity tests (PVTs) and symptom validity tests (SVTs) (Slick, D.J., Sherman, E.M.S., & Iverson, G. L. (1999). Diagnostic criteria for malingered neurocognitive dysfunction: Proposed standards for clinical practice and research. The Clinical Neuropsychologist, 13(4), 545-561). However, the MND criteria are long overdue for revision to address advances in malingering research and to address limitations identified by experts in the field. METHOD: The MND criteria were critically reviewed, updated with reference to research on malingering, and expanded to address other forms of malingering pertinent to neuropsychological evaluation such as exaggeration of self-reported somatic and psychiatric symptoms. RESULTS: The new proposed criteria simplify diagnostic categories, expand and clarify external incentives, more clearly define the role of compelling inconsistencies, address issues concerning PVTs and SVTs (i.e., number administered, false positives, and redundancy), better define the role of SVTs and of marked discrepancies indicative of malingering, and most importantly, clearly define exclusionary criteria based on the last two decades of research on malingering in neuropsychology. Lastly, the new criteria provide specifiers to better describe clinical presentations for use in neuropsychological assessment. CONCLUSIONS: The proposed multidimensional malingering criteria that define cognitive, somatic, and psychiatric malingering for use in neuropsychological assessment are presented.

Chance-level hit rates in closed-set, forced-choice audiometry and a novel utility for the significance test-based detection of malingering.

The primary aim of this study was to extend existing theory on the relationship between chance-level performance and the number of alternatives and trials in closed-set, forced-choice speech audiometry and sound localization methods. When calculating chance performance for closed-set, forced-choice experiments with multiple trials, the binomial distribution should be preferred over the simple 1/a probability, as the latter is appropriate only for single trial experiments. The historical use of constant hit rates for determining chance performance has been based upon the assumption that random hits are distributed evenly across multiple trials. For any closed-set, forced-choice task with 2 to 10 alternatives and 2 to 100 trials, we calculated the probability of obtaining any given hit rate due to random guessing alone according to the binomial distribution. Hit rates with probabilities p > 0.05 were interpreted as being likely to occur due to random chance alone, whereas hit rates with probabilities of p ≤ 0.05 were interpreted as being unlikely to occur due to chance alone. For sound localization experiments with speakers at fixed positions, the expected probability of a random hit was also calculated using the binomial distribution. The expected angular root mean square (rms) error in sound localization resulting from the random selection of sound sources was investigated using Monte Carlo simulations. A new aspect in the interpretation of test results was identified for situations in which the observed number of hits is much lower than would be expected due to chance alone. For test methods incorporating a relatively low number of alternatives and a sufficiently high, yet clinically feasible, number of trials, both upper and lower thresholds for chance-level performance could be identified. This lower threshold represents the lowest hit rate which can be expected through random chance alone. Extending interpretation of results to include this lower threshold affords the ability to not only identify performance significantly superior to that of chance, but also that significantly poorer than chance and thereby represents a simple method for the objective detection of malingering.

Racial and Gender Disparities in Diagnosis of Malingering in Clinical Settings.

PURPOSE: A malingering diagnosis can have consequences for patient care in the emergency room, hospital, and outpatient settings. Use of this diagnosis along racial and gender demographics has not been explored in clinical settings. OBJECTIVE: To determine any differences in socio-demographic characteristics among patients diagnosed with malingering in non-psychiatric inpatient hospitals and emergency departments in the USA. METHODS: The National Inpatient Sample (NIS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) databases were utilized to identify a malingering diagnosis from 2003 to 2015. Racial, ethnic, and gender disparities were examined. RESULTS: The malingering diagnosis is prevalent in 0.1% of both settings. The diagnosis is more prevalent in men than women. Among inpatients, malingering diagnosis was twice as prevalent among blacks compared with whites. The adjusted OR showed similar likelihood among blacks and whites with Hispanic men having the lowest likelihood for the diagnosis. Black women were slightly more likely, while Hispanic women were less likely to be diagnosed than white women. In ED settings, whites had the highest prevalence and a higher adjusted OR for malingering diagnosis compared with other races. There was no gender difference. CONCLUSION: The racial demographics of malingering diagnosis differ between clinical settings. Blacks may have a higher risk to receive the diagnosis as inpatients, whereas whites may have a higher risk in EDs. Hispanics have the lowest likelihood of the diagnosis in both settings. This data suggests a complex, multi-layered phenomenon highlighting how patients are diagnosed with malingering.

Malingering and Defensiveness on the Spanish Personality Assessment Inventory: An Initial Investigation with Mostly Spanish-Speaking Outpatients.

Psychological assessments can be essentially invalidated by examinees' intentional response styles, such as feigning (i.e., fabrication or marked overreporting of symptoms/impairment) and defensiveness (i.e., denial or minimization of symptoms/impairment). As a psychometric strength, the Personality Assessment Inventory (PAI) has established validity indicators for identifying both response styles. With the United States' increasing ethnic and cultural diversity, predominantly Spanish-speaking individuals are now estimated in the range of 15 million persons. Unfortunately, very little research has been conducted on the Spanish-translated PAI regarding its effectiveness in clinical populations. Using a between-subjects design, a sample of mostly Spanish-speaking outpatients was randomly assigned to genuine, feigning, or defensive conditions. For feigning, PAI malingering indicators using rare symptoms strategies (i.e., Negative Impression [NIM] and Negative Distortion [NDS] scales) demonstrated moderate to large effect sizes. For defensiveness, the Defensive (DEF) index proved the most effective with a very large effect size (M = 1.68). Different cut scores were examined to increase the clinical utility of the Spanish PAI for determining response styles.

Comparing two models of performance validity assessment in patients with Parkinson's disease who are candidates for deep brain stimulation surgery.

Utility of standalone and embedded performance validity tests (PVTs) as well as the decision-making algorithms used to reach clinical conclusions about credible and noncredible performance can be population specific. To better understand PVT utility in Parkinson's disease candidates for deep brain stimulation (DBS) we present on two aims: 1) establishing the frequency data of below-criterion responding for the Medical Symptom Validity Test and three embedded PVTs in a sample of 47 patients with Parkinson's disease, and 2) comparing the efficacy of two models for clinical-decision making regarding noncredible performance. Consistent with expectations from previous studies and desired specificity values, our retrospective analysis indicated that in this sample of presumably well-motived patients, the rate of below-criterion responding was less than 10% for all PVTs administered. Regarding our model comparison, we compared a typical PVT battery that required administration of a standalone measure in all cases against a recently proposed low risk algorithm that attempts to lower testing burden by relying more heavily on embedded PVTs with administration of a standalone measure only in the event of below-criterion performance on an embedded indicator. Results suggest that for patients with Parkinson's disease judged to be at limited risk for noncredible performance, a low risk PVT model may prove both more efficient and less prone to error than a more typical model. Implications for clinical decision-making are discussed, as are limitations of the study and its generalizability.