Experimental Evidence on Stress and In-group Preference

Knowing whether acute stress results in stronger in-group preference is important for policymakers inside and outside of Africa. This research project provides evidence for whether ethnic tensions are likely to be heightened if a society experiences acute stressors, such as economic, social, or environmental shocks. Examples of these might be natural disasters, droughts, political conflicts, riots, and protests. These findings are also important for a better understanding of the importance of groups, which are a fundamental aspect of human behavior. The new knowledge should also be important for helping governments understand how best to alleviate inter-group conflict in the face of macroeconomic shocks that increase acute stress.

The research project aims to better understand the determinants of ethnic preferences within the African context; specifically, how they are affected by acute stress. It is hypothesized that in-group preferences might become stronger during times of heightened stress. The study tests this by examining the consequences of acute stress induced by the provision of hydrocortisone pills to experiment participants. For a randomly chosen treatment group, the researchers directly increase levels of the stress hormone cortisol by pharmacologically administering its physiological precursor, hydrocortisone. A randomly chosen control group receives an identical-looking placebo pill. Participants in both conditions then undertake standard behavioral games that test whether there is greater trust, trustworthiness, altruism, or generosity towards coethnics. By comparing the behaviors of those in the stress condition versus those in the control condition the research team can assess whether stronger coethnic preferences arise during episodes of heightened stress. The structure of the experiment also allows the research team to test whether acute stress affects other forms of in-group preferences such as own-age or own-gender preference.