Why Opt-Out Defaults Diminish Living Organ Donations

Opt-out defaults can motivate people towards more pro-social behavior and many countries have adopted opt-out policies to increase organ donation, energy conservation, or childhood vaccination. While opt-out defaults target specific cooperative behaviors (e.g., deceased organ donations), we present evidence that they can have negative spillover effects on related cooperative behaviors (e.g., living organ donations). Across three studies, we show that this effect is due to enhanced trust in organ supply under opt-out. This interpretative change reduces living organ donations by (i) undermining reputation effects and (ii) making people less willing to donate to others low in genetic relatedness and emotional closeness (e.g., stranger). Notably, these effects are larger for people with stronger pure altruistic tendencies. The findings provide initial understanding of when and why opt-out defaults have negative spillover effects and offer valuable implications for policymakers and marketers.