Detecting feigned cognitive impairment using pupillometry on the Warrington Recognition Memory Test for Words.

OBJECTIVE: Pupillometry provides information about physiological and psychological processes related to cognitive load, familiarity, and deception, and it is outside of conscious control. This study examined pupillary dilation patterns during a performance validity test (PVT) among adults with true and feigned impairment of traumatic brain injury (TBI).

PARTICIPANTS AND METHODS: Participants were 214 adults in three groups: adults with bona fide moderate to severe TBI (TBI; n  = 51), healthy comparisons instructed to perform their best (HC; n  = 72), and healthy adults instructed and incentivized to simulate cognitive impairment due to TBI (SIM; n  = 91). The Recognition Memory Test (RMT) was administered in the context of a comprehensive neuropsychological battery. Three pupillary indices were evaluated. Two pure pupil dilation (PD) indices assessed a simple measure of baseline arousal (PD-Baseline) and a nuanced measure of dynamic engagement (PD-Range). A pupillary-behavioral index was also evaluated. Dilation-response inconsistency (DRI) captured the frequency with which examinees displayed a pupillary familiarity response to the correct answer but selected the unfamiliar stimulus (incorrect answer).

RESULTS: All three indices differed significantly among the groups, with medium-to-large effect sizes. PD-Baseline appeared sensitive to oculomotor dysfunction due to TBI; adults with TBI displayed significantly lower chronic arousal as compared to the two groups of healthy adults (SIM, HC). Dynamic engagement (PD-Range) yielded a hierarchical structure such that SIM were more dynamically engaged than TBI followed by HC. As predicted, simulators engaged in DRI significantly more frequently than other groups. Moreover, subgroup analyses indicated that DRI differed significantly for simulators who scored in the invalid range on the RMT ( n  = 45) versus adults with genuine TBI who scored invalidly ( n  = 15).

CONCLUSIONS: The findings support continued research on the application of pupillometry to performance validity assessment: Overall, the findings highlight the promise of biometric indices in multimethod assessments of performance validity.