The Network Dynamics of Anti-Prejudice Norms: A Field Experiment Testing Anti-Prejudice Interventions in Real Groups

Individuals’ attitudes towards members of ethnic and national outgroups can be shaped by peer norms within their social networks. However, little is known about the interplay between such spontaneous normative influence processes within social networks and more formalised top-down norms communicated by institutions (e.g., schools). To test this impact, we conducted a longitudinal four-wave field experiment employing social-network analysis among real groups. Students enrolled in Dutch and international psychology bachelor programmes at a Dutch university were assigned to mentoring groups (N = 288 across 50 groups in the last wave). As the institutional intervention, they watched an online diversity training video (vs. not, between participants) at the beginning of data collection (T1), and attended a diversity and inclusion session (within-participants) before T2. At each timepoint, participants reported attitudes towards outgroup members and (ingroup and outgroup) friendships with students enrolled in the same programme. We examined how peer norms (i.e., friends’ intergroup attitudes) and institutional interventions shape intergroup attitudes, finding that our institutional intervention improved intergroup attitudes and facilitated the spread of positive peer norms within networks over time.