Direct and indirect measures of context in patients with mild-to-severe traumatic brain injury (TBI): The additive contribution of eye tracking.

Introduction: The facilitation of memory for target stimuli due to the similarity of context in the learning and testing phases is known as the "Context-Effect" (CE). Previous studies reported that TBI affects memory for contextual information when tested directly. However, the indirect effect of contextual information on memory of target (i.e., CE) is preserved. Several studies have demonstrated that CE is composed of multiple, distinct cognitive processes. The present study includes four context conditions to enable identification of the exact process affected by TBI. In addition, eye movements were monitored to test three hypotheses: first, that the TBI group's dwell time on target (DTOT) at encoding would be less than that of controls. Second, that DTOT at encoding would be more highly associated with recognition at test for the control group than for the TBI group. Third, that overall DTOT at encoding on new, as compared to old items ("repetition effect"), would be less pronounced for the TBI group as compared to controls. Methods: Twenty-four patients with mild-to-severe TBI and 23 matched controls participated in this study. We presented participants with photographs of male faces shown wearing distinctive, trial-unique hats (yielding specific Target-Context pairing). Eye movements were recorded throughout the test task. Results: Memory for faces following TBI is impaired compared to that of controls. The magnitude and pattern of CE are the same for both groups. The TBI group has a lower DTOT compared to that of controls. However, the relative length of DTOT in the various conditions is similar in both groups. Conclusions: Behavioral results indicate that although the TBI group has impaired memory for faces, the CE pattern is similar to that of controls. Similarly, in terms of eye movements, although the TBI group focuses less on target, relations between the various conditions are similar in both groups.