ABSTRACT Trauma triage predisposes to diagnostic errors because of the need for decision making under conditions of uncertainty and time-pressure. Diagnostic errors increase mortality, disability, pain, and loss of independence. Elderly patients are particularly vulnerable because they not only disproportionately experience these errors but also lack the resilience to tolerate sub-optimal care. The absence of interventions to improve the diagnostic process is a critical barrier to alleviating the burden that injury imposes on patients. In prior work, our team developed two customized, theoretically-based video games to improve the recognition of severely injured patients. The games had moderate efficacy in the laboratory, despite only variable success at engaging participants in the task. Our overarching hypothesis is that by increasing engagement we can amplify the potency of the interventions. The objective of this R21 proposal is to test the feasibility of using deliberate practice – goal-oriented training in the presence of a coach who can provide personalized, immediate feedback – to increase engagement. The research design involves recruitment of a national convenience sample of board-certified emergency physicians who will serve as trainees (n=30), pairing of the trainees with a coach, delivery of three 30-minute coaching sessions using the existing games as the training task, and assessment of the effect of the combined intervention on performance in the laboratory. The specific aims of the R21 are: 1. To assess the fidelity of intervention delivery by measuring coaching skill acquisition, coaching skill drift and protocol adherence. 2. To assess the potential effect size of the intervention by comparing trainee performance on a validated virtual simulation with a control group of physicians (n=30). 3. To assess the acceptability of the intervention by using a mixture of validated instruments and semi- structured debriefing interviews with trainees to assess their engagement with the intervention. Results will inform a future trial to compare the efficacy of different behavioral interventions in reducing diagnostic error in trauma triage, and in the long-term should help to mitigate the burden imposed by trauma on the health and independence of the aging.