Regret is the prototypical decision related emotion. It is felt when the outcome of a non-chosen alternative is better than the outcomes obtained. Regret is a functional emotion that helps people to correct mistakes. It is also functional because people can anticipate regret beforehand, then choose in such a way as to avoid regret from happening. Researchers in economics proposed regret theory, an alternative to rational choice theory, which takes into account the anticipation of regret and its influence in choice. Researchers in psychology studied how anticipations of regret influence decision making in a variety of domains, including health behaviors. The findings suggest that interventions can be developed that are based on the idea that people are regret averse.