Does asking people about their future behavior increase or decrease the likelihood that they will repeat their past behavior? In two laboratory and two field experiments, we find that behavior prediction strengthens behavior repetition, making people more likely to do what they normally do, when personal norms regarding engaging in a behavior are weak or not easily accessible. However, when personal norms are strong or made accessible at the time of the prediction request, behavior prediction weakens behavior repetition and increases the likelihood that people do what they think they should do-even if it's not what they normally would do. These findings provide new tools for influencing behavior repetition, reconcile some seemingly contradictory past findings, and contribute to the debate regarding the relative importance of habits and intentions in guiding behavior. T he repetition of unhealthy behaviors (such as overeating) and the lack of repetition of healthy behaviors (such as exercising) are leading contributors to preventable deaths in developed countrie
