Does Promoting One Healthy Behavior Detract from Others? Evidence from a Field Experiment

Impact evaluations of behavioral interventions typically focus on target outcomes. Might interventions induce negative spillovers on other behaviors? I run a large field experiment in which individuals receive combinations of messages and incentives promoting two healthy behaviors, meditation and meal logging. I find that the interventions reduce completion rates of the opposite behavior by 19–29 percent. I find that interventions with larger target effects do not necessarily generate larger negative spillovers, and demonstrate implications for cost-effectiveness analysis. I investigate the mechanisms behind the observed spillovers.