Determining whether false positive rates increase with performance validity test battery expansion

Objective: Performance validity test (PVT) misclassification is an important concern for neuropsychologists. The present study determined whether expanding PVT analysis from 4-PVTs to 8-PVTs could lead to elevated rates of false positive performance validity misclassifications. Method: Retrospective analysis of 443 patients who underwent a fixed neuropsychological test battery in a mixed clinical and forensic setting. Rates of failing two PVTs were compared to those predicted by Monte Carlo simulations when PVT analysis extended from 4-PVTs to 8-PVTs. Indeterminate performers (IDT; n = 42; those who failed two PVTs only after PVT analysis extended from 4-PVTs to 8-PVTs) were compared to a PVT-Fail group (n = 148; those who failed two PVTs in the 4-PVT battery or failed >2 PVTs). Results: Rate of failing two PVTs remained stable when PVT analysis extended from 4- to 8-PVTs (12.9 to 11.9%) and was significantly lower than those predicted by Monte Carlo simulations. Compared to PVT-Fail, the IDT group was significantly younger, had stronger neuropsychological test performance, and demonstrated comparable rates of forensic referral and conditions with known neurocognitive sequelae (e.g. stroke, moderate-to-severe TBI). Conclusions: Monte Carlo simulations significantly overestimated rates of individuals failing two PVTs as PVT battery length doubled. IDT did not differ from PVT-Fail across variables with known PVT effects (e.g. age, referral context, neurologic diagnoses), lowering concern that this group is comprised entirely of false-positive PVT classifications. More research is needed to determine the effect of PVT battery length on validity classification accuracy.