Regret (emotion)

Overview
Regret is an intelligent (and/or emotional) dislike for personal past acts and behaviors. Regret is often felt when someone feels sadness, shame, embarassment or guilt after committing an action or actions that the person later wishes that he or she had not done. Regret is distinct from guilt, which is a deeply emotional form of regret — one which may be difficult to comprehend in an objective or conceptual way. In this regard, the concept of regret is subordinate to guilt in terms of its "emotional power." By comparison, shame typically refers to the social (rather than personal) aspect of guilt or (in minor context) regret as imposed by the society or culture (enforcement of ethics, morality), which has substantial bearing in matters of (personal and social) honor.

Regret can describe not only the dislike for an action that has been committed, but also, importantly, regret of inaction. Many people find themselves wishing that they had done something in a past situation.

Models
There are extremely specific models of regret mostly in economics and finance. Of these, the most clearly emotional is buyer's remorse, also called buyer's regret.

A much less emotional formulation is investor's regret which is a risk measure. Financial theorist Ron Dembo equates these and claims that regret, modified by a risk aversion factor, is the only reliable indicator of risk shared among all investors.