This article reviews 418 experiments (conducted between 2007-2019) on reducing prejudice (based on race, ability, nationality, and other factors).
It builds on an earlier (2009) review by the same authors.
This new review highlights seven interventions that seem to work (many experiments testing the intervention done, showing sizeable effects on reducing prejudice):
Antibias, multicultural, and moral education (e.g. teaching health care providers strategies to combat mental illness stigma). Still, more field experiments may be needed.
Cognitive and emotional training. Including cognitive conditioning (e.g. pairing representations of stigmatised groups with positive stimuli); cognitive-emotional interventions (e.g. training to reduce negative emotions when encountering situations related to outgroups); and perspective taking (e.g. taking the "perspective of the elderly by climbing up a staircase while wearing restrictive knee pads").
Peer influence, discussion, and dialogue (e.g. using peers as messengers for a cause). Experiments show slightly smaller effects than other interventions.
Social categorization (e.g. modifying existing boundaries between groups, by asking research participants to list characteristics shared between groups).
Entertainment (e.g. incorporating "educational messages about prejudice into an entertaining storyline of a soap opera or film").
Face-to-face contact (e.g. assigning soldiers of minority group and majority group to room with one another during basic training).
Extended and imagined contact (e.g. reading children stories in which able-bodied children befriend children with disabilities). But larger experiments show much smaller effects (in reducing prejudice).
The review also highlights two interventions with mixed evidence / need more evidence:
Diversity training (programmes that "self-identify as a diversity training" or related e.g. sensitivity / cultural competence). Among the studies, only a small number of experiments conducted. Further, experiments with larger sample sizes find quite small effects (i.e. diversity training reduces prejudice very slightly).
Value consistency and self-worth (e.g. reminding someone of their (or their group’s) egalitarian preferences). Many lab and online experiments have shown sizeable effects (in reducing prejudice). But no field experiments have been done.
The review emphasises three overall limitations in the body of research (the 418 experiments it reviewed).
The majority (76%) of the studies only evaluate light touch interventions, for which the long-term impact remains unclear.
Publication bias may be exaggerating effects. The review found that experiments with larger sample sizes systematically showed larger effects (in reducing prejudice), compared to experiments with smaller sample sizes (which suggests small sample size experiments showing smaller effects have not been published).
Landmark studies often find limited effects (in reducing prejudice).