Failing more freestanding performance validity tests results in progressive artificial lowering of invalid neuropsychological test scores.

Abstract

Background: Administering multiple performance validity tests (PVTs) is essential throughout neuropsychological evaluations to objectively determine test performance validity, with ≥2 PVT failures generally indicating invalid performance. However, the impact of exceeding this standard invalidity threshold remains unclear. This study explored whether neuropsychological test scores are artificially lowered in a "dose-dependent" manner as the number of freestanding PVT failures increases.

Methods: Cross-sectional analysis was conducted on 358 clinical referrals from an academic medical center who underwent neuropsychological evaluations. All patients were administered 5 freestanding PVTs and a battery of 12 neuropsychological tests, which were also used to compute a neuropsychological test composite score calculated from averaging all 12 individual test scores. Analyses of variance examined differences in mean test scores across PVT failure groups (0,1,2,3, and 4-5 failures).

Results: As the number of PVT failures increased, patients showed significantly more artificial lowering of neuropsychological test scores. The composite T-score had the largest effect size (ηp²=.348), with those failing 4-5 PVTs scoring over 2 standard deviations below the population mean. Higher PVT failure groups (3-5) had elevated rates of external incentives, primary psychiatric diagnoses/attention-deficit/hyperactivity disorder, and lower rates of primary medical/neurologic conditions.

Conclusions: Results support a dose-dependent relationship between freestanding PVT failures and neuropsychological test scores such that additional PVT failures resulted in progressively more pronounced artificial lowering of scores. Findings highlight the importance of considering the number of PVT failures along with binary valid/invalid classification in diagnostic contexts, especially in psychiatric populations, where higher rates of PVT failure are observed.