Detecting Simulated Versus Bona Fide Traumatic Brain Injury Using Pupillometry

• Published in: Neuropsychology Vol. 35; no. 5; pp. 472 - 485
• Main Authors: Patrick, Sarah D., Rapport, Lisa J., Kanser, Robert J., Hanks, Robin A., Bashem, Jesse R.
• Format: Journal Article
• Language: English
• Published: United States American Psychological Association 01-07-2021
• Subjects: Deception; Familiarity; Human; Malingering; Pupil Dilation; Simulation; Traumatic Brain Injury; malingering; pupillometry; traumatic brain injury; performance validity
• ISSN: 0894-4105; 1931-1559
• DOI: 10.1037/neu0000747

Objective:
Pupil dilation patterns are outside of conscious control and provide information regarding neuropsychological processes related to deception, cognitive effort, and familiarity. This study examined the incremental utility of pupillometry on the Test of Memory Malingering (TOMM) in classifying individuals with verified traumatic brain injury (TBI), individuals simulating TBI, and healthy comparisons.
Method:
Participants were 177 adults across three groups: verified TBI (n = 53), feigned cognitive impairment due to TBI (SIM, n = 52), and heathy comparisons (HC, n = 72).
Results:
Logistic regression and ROC curve analyses identified several pupil indices that discriminated the groups. Pupillometry discriminated best for the comparison of greatest clinical interest, verified TBI versus simulators, adding information beyond traditional accuracy scores. Simulators showed evidence of greater cognitive load than both groups instructed to perform at their best ability (HC and TBI). Additionally, the typically robust phenomenon of dilating to familiar stimuli was relatively diminished among TBI simulators compared to TBI and HC. This finding may reflect competing, interfering effects of cognitive effort that are frequently observed in pupillary reactivity during deception. However, the familiarity effect appeared on nearly half the trials for SIM participants. Among those trials evidencing the familiarity response, selection of the unfamiliar stimulus (i.e., dilation-response inconsistency) was associated with a sizeable increase in likelihood of being a simulator.
Conclusions:
Taken together, these findings provide strong support for multimethod assessment: adding unique performance assessments such as biometrics to standard accuracy scores. Continued study of pupillometry will enhance the identification of simulators who are not detected by traditional performance validity test scoring metrics.
Key Points
Question:
Is pupillometry a useful biometric measure for identifying feigned cognitive impairment?
Findings
: Several pupillary indices discriminated feigned impairment from healthy adults and adults with TBI instructed to perform their best, both as independent indicators and beyond traditional TOMM accuracy scores.
Importance:
The findings support the utility of biometric measures, such as pupillometry, in the context of performance validity assessment.
Next Steps:
The examination of pupillometry may enhance the detection of individuals feigning cognitive impairment who are not identified by traditional performance validity tests.