Lowered cutoffs to reduce false positives on the Word Memory Test

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.