Replication Data for: Hawkish Biases and Group Decision-Making

How do cognitive biases relevant to foreign policy decision-making aggregate in groups? Many tendencies identified in the behavioral decision-making literature – such as reactive devaluation, intentionality bias, and risk-seeking in the domain of losses – have all been linked to hawkishness in foreign policy choices, potentially increasing the risk of conflict, but the way in which these “hawkish biases" operate in the small group contexts in which foreign policy decisions are often made is unknown. We field three large-scale group experiments to test how these biases aggregate in groups. We find that groups are just as susceptible to these canonical biases as individuals, with neither hierarchical nor horizontal group decision-making structures significantly attenuating the magnitude of bias. Moreover, diverse groups perform similarly to more homogeneous ones, exhibiting similar degrees of bias and marginally increased risk of dissension. These results suggest that at least with these types of biases, the “aggregation problem" may be less problematic for psychological theories in IR than some critics have argued. This has important implications for understanding foreign policy decision-making, the role of group processes, and the behavioral revolution in IR.