While there is a significant body of research on diversity training dating back decades, many studies rely on surveys that ask how participants felt about the training or assess what they’ve learned, while relatively few try to determine whether the training changed how people behave.

Few of the studies use randomized controlled trials, considered the gold standard to measure the effectiveness of treatments and interventions.

The studies that do exist have found mixed results. Some show that participants learn about people from other backgrounds and that training can have an effect on beliefs and behaviors (although the latter fades over time). Others show that diversity-training programs can trigger negative feelings in participants and even harm the very groups they’re intended to help.