Forced to face the truth: A meta-analysis on the effectiveness of moral reminders

Moral reminders, also referred to as moral appeals or moral nudges, are widely used by governments, companies, and NGOs to promote pro-social behavior. These appeals function by either increasing the salience of moral concerns or the cost of diverting attention away from relevant information on payoffs or social norms. Drawing on over 400 studies across psychology, sociology, management and economics, we present a meta-analysis of their effects. Our findings reveal that, on average, moral reminders are effective, with an effect size (Hedge's g) of 0.24 in a random-effects model, but with significant backfiring occurring in 12% of studies. We identify sources of heterogeneity based on disciplinary focus and design choices. Crucially, we introduce a taxonomy of moral reminders: we distinguish those that provide information on consequences, those that highlight descriptive or injunctive norms, and those that prime moral awareness. Our analysis shows that all of these instruments are effective, particularly those providing information on consequences, whereas information on injunctive norms is more likely to backfire.