Objective: The present study tested the incremental utility of response time (RT) on the Warrington Recognition Memory Test - Words (RMT-W) in classifying bona fide versus feigned TBI.
Method: Participants were 173 adults: 55 with moderate to severe TBI, 69 healthy comparisons (HC) instructed to perform their best, and 49 healthy adults coached to simulate TBI (SIM). Participants completed a computerized version of the RMT-W in the context of a comprehensive neuropsychological battery. Groups were compared on RT indices including mean RT (overall, correct trials, incorrect trials) and variability, as well as the traditional RMT-W accuracy score.
Results: Several RT indices differed significantly across groups, although RMT-W accuracy predicted group membership more strongly than any individual RT index. SIM showed longer average RT than both TBI and HC. RT variability and RT for incorrect trials distinguished SIM-HC but not SIM-TBI comparisons. In general, results for SIM-TBI comparisons were weaker than SIM-HC results. For SIM-HC comparisons, classification accuracy was excellent for all multivariable models incorporating RMT-W accuracy with one of the RT indices. For SIM-TBI comparisons, classification accuracies for multivariable models ranged from acceptable to excellent discriminability. In addition to mean RT and RT on correct trials, the ratio of RT on correct items to incorrect items showed incremental predictive value to accuracy.
Conclusion: Findings support the growing body of research supporting the value of combining RT with PVTs in discriminating between verified and feigned TBI. The diagnostic accuracy of the RMT-W can be improved by incorporating RT.
Keywords: Malingering; performance validity; response time; traumatic brain injury.