According to a study that evaluated how prejudice can be reduced when rival groups come together, having Muslim teammates caused Christian players in Iraq to change their behavior for the better toward their Muslim counterparts. However, the preregistered study - which sought to rigorously analyze the policy-relevant "contact hypothesis," which has been studied for years and serves to inform funding of social programming - also revealed this hypothesis's limitations; behavioral improvements developed in the soccer league did not generalize to broader non-soccer settings, the study showed. In a related Perspective, Elizabeth Levy Paluck and Chelsey S. Clark write that while some may classify this research as an application of a well-known finding, this would be inaccurate. "Previous research [on the contact hypothesis] has not demonstrated cause and effect with real-world interventions," they write. They say this makes the new study more similar to basic science that makes progress toward fundamental evidence.
The contact hypothesis - a widely recognized theory that suggests the social prejudices between groups can be eased through meaningful intergroup cooperation - often serves as the basis for real-world strategies designed to facilitate peace. Based in part on this idea, billions of dollars are spent globally on peacebuilding programs focused on exposure to outgroups. However, empirical studies that critically evaluate the theory's suppositions are almost non-existent. In a field experiment designed to assess whether intergroup contact can build social cohesion after war, Salma Mousa intervened in an amateur soccer league where ISIS-displaced Iraqi Christian players were randomly assigned to either an all-Christian team or a team mixed with three Muslim players. After league play, Mousa measured the behaviors of players, as well as a set of outcomes focused on attitudes, and discovered that that having a mixed team caused Christian players to change their behaviors towards their Muslim peers, but only in ways that related to soccer. In mixed teams, Christian players became more likely to give Muslim players sportsmanship awards and to continue to play and train with them after league play. Thus, they showed changes in behavior, though not attitude, according to survey results. However, according to Mousa, the observed behavioral changes did not extend into other social contexts with Muslim strangers, such as attending a Muslim restaurant or mixed social event with strangers. In the Perspective, Paluck and Clark suggest one reason the positive behavioral effects may not have generalized out of the soccer league context is because they were limited to behaviors, not attitudes - a finding consistent with other recent prejudice reduction research. They write, "Future work can...disentangle whether attitudes are simply more difficult to change [than behaviors] or whether current research is not measuring the correct attitudes." The findings of the study by Mousa highlight the value and potential limits of using intergroup interventions for achieving post-war peace. Future work, she says, should explore the extent to which localized cohesion can shield related communities from, for example, resurgences in ethnic violence.