"We Know What We Don't Know" a reflexive synthesis of research and lay knowledge regarding group decision-making in mountaineering.

Groups navigating dynamic and hazardous mountain environments must continuously engage in collective decision-making. However, the assumption that groups naturally make better decisions than individuals is misleading. Groupthink, group polarization, and other social dynamics can impair judgement and lead to sub-optimal or even dangerous outcomes, making group decision-making a critical factor for safety in mountaineering. This scoping review maps the existing research on group decision-making in mountaineering using a systematic literature search complemented by reflexive thematic analysis. From 107 identified articles, we derived 14 themes, subsumed within six layers of influence, including factors benefitting group-decision making, authenticity, social influence, external pressure, expertise and contextual dynamics. Together, these themes underscore the complexity of group decision-making in the high-stakes environment. Our findings highlight its central role in mountaineering and provide useful directions for future research and practice.