Promoting cooperation between different groups remains one of society's biggest challenges. We examine whether such intergroup cooperation can be fostered through in-group observation, using a lab-in-the-field experiment in Papua New Guinea. Our main result is that observation by a key in-group member increases the share of people who cooperate with members of other communities from 17 percent to 70 percent, thereby eliminating the in-group bias in cooperation. We relate this to a shared understanding among participants that intergroup cooperation is socially desirable. Our findings suggest that policymakers, communities, and organizations may leverage in-group observation to improve intergroup cooperation.
In many countries, partisans have become increasingly biased in how they evaluate others based on political affiliation. We suggest that this increase in affective polarization may in part be caused by changes in the global power distribution which caused many countries to experience a long period without external (military) threats. To study the importance of external threats, we conduct a priming experiment to examine how making Russia's full-scale invasion of Ukraine in 2022 salient causally influences affective polarization and collaboration in the U.S. We find that priming Americans with Russia's military aggression leads to a modest reduction in affective polarization and an increase in cooperativeness as measured by behavior in an incentivized coordination game. Surprisingly, the effect of making Russia's invasion salient does not depend on perceived cross-party disagreement about the conflict. These results suggest that researchers should also consider international relations to understand within-country polarization and willingness to collaborate.