Introduction/Background A core element of simulation-based trainings is the debriefing after the simulation scenario.1 Yet, evidence as to how such debriefings should be guided by the instructor so that trainees benefit most effectively is just beginning to emerge.2 In particular, indepth analyses of the functions of different interventions of the debriefers are rare.3 Understanding what debriefers actually do during debriefings and how these actions might impact the learner’sreflections could help debriefers facilitate effectively and simulation faculty development programs target debriefing techniques more accurately. Methods We videotaped and qualitatively analyzed seven 45-60 minute debriefings conducted during Anesthesia Crisis Resource Management Courses. Debriefers and learners communications were coded independently. Debriefers statements and inquiries were coded based on current debriefing concepts (e.g., regarding type of advocacy, type of inquiry).1,4 Learners reactions were coded based on Gibbs reflective cycle.3,5 Results Forty two anesthesia residents and nurses and three debriefers participated. We found that debriefers asked various types of questions (e.g., regarding emotions, cognitions, ideas, circular), stated a variety of advocacies (e.g., observations, ’pseudo-observations’ [e.g., “Here you were thinking that …”], opinions, appreciations) and used further intervention techniques such as previewing, paraphrasing, medical and psychological input. Overall, the amount of inquiries was twice as low than the amount of other communication types. We also found that learners communications consisted mostly of descriptions, explanations and Conclusions whereas indepth reflections such as mental models were rare. Performing a lag sequential analysis - a method for analyzing temporal patterns in sequentially coded interactions to detect whether behavior sequences emerge above chance, we analyzed what types of debriefer communications were followed by learners revealing mental models.6 We found that learners revealed mental models after the debriefers asked for ideas (Z=3.59; p < 0.001), made implicit suggestions (e.g., “So, here you were not sure what to do, right?”) (Z= 2.13; p < 0.05), asked a systemic questions (e.g., “What would you have needed from here to speak up?”) (Z=3.59; p < 0.001), and paraphrased learners statements (Z=3.17; p < 0.001). Other types of debriefer interventions did not elicit learners’ mental models. Conclusion We found that debriefers used a broad spectrum of micro-level debriefing techniques but that only some of them elicited the revealing of mental models by learners. This is an important finding as it provides ideas on how to detect and address learners mental models more efficiently during the debriefing. We also found that debriefers used more ’telling’ than ’inquiring’. Further research should investigate the optimal balance of these two very different kinds of communication.7