What Is Regret Theory?

Regret Theory is a decision-making model in behavioral economics and finance that incorporates the emotional response of regret into the evaluation of choices under uncertainty. Unlike traditional models based solely on expected utility, Regret Theory acknowledges that individuals not only consider potential outcomes but also how those outcomes compare to what could have occurred had they made different choices. This theory was developed to better explain choices that appear inconsistent with standard utility maximization, particularly when individuals face uncertainty and irreversible outcomes.

The central idea behind Regret Theory is that people anticipate the regret they might feel if they make a suboptimal decision and that this anticipation affects their preferences and actions. The theory suggests that minimizing potential future regret, rather than maximizing utility alone, often drives behavior in economic and financial contexts.

Origins and Development

Regret Theory emerged as part of the broader movement challenging the assumptions of expected utility theory, particularly its inability to account for real-world behavior. The formalization of Regret Theory is commonly attributed to the work of Graham Loomes and Robert Sugden in the early 1980s. Their research provided a mathematical model in which the utility of a choice includes not just its direct payoff but also a regret or rejoicing term, reflecting how the outcome compares with alternatives.

This theoretical framework builds on earlier critiques of rational choice models by integrating psychology into economic decision-making. It aligns with a broader class of non-expected utility theories that seek to describe how people actually make choices, rather than how they should make choices under assumptions of rationality.

How It Works

Under Regret Theory, the utility of an outcome is influenced by both the absolute result and a comparison to what could have been achieved with a different decision. If the chosen option results in a worse outcome than an unchosen alternative, the individual experiences regret. Conversely, if the outcome is better than that of the alternative, the person may feel a sense of rejoicing. This contrast effect alters the perceived attractiveness of choices.

Formally, the regret-adjusted utility of a particular action depends on:

• The outcome of the action chosen.
• The outcomes of alternative actions that were not chosen.
• A regret function that assigns a disutility value based on the difference between the actual and foregone outcomes.

This model implies that decision-makers are not only sensitive to outcomes but also to the foregone alternatives, particularly when feedback is available after the decision. When individuals expect to receive information about unchosen outcomes, they may act more conservatively to avoid possible regret. When no feedback is expected, regret plays a smaller role.

Applications in Finance

Regret Theory is particularly useful in explaining behavior in financial decision-making contexts where feedback about missed opportunities is common. This includes:

Investment Decisions: Investors may avoid risky assets not only due to risk aversion but also because they fear regretting losses more than they value potential gains. Regret aversion may cause investors to hold underperforming stocks to avoid admitting a mistake (the disposition effect) or to follow herd behavior to avoid being the only one who made a wrong call.

Portfolio Choice: Traditional mean-variance optimization assumes rational utility maximization. Regret Theory suggests that investors might prefer portfolios that reduce the likelihood of underperforming a benchmark or peer group, even at the expense of expected returns.

Behavioral Biases: Regret aversion has been used to explain anomalies such as excessive trading, under-diversification, and the tendency to prefer familiar assets. These behaviors can be viewed as strategies to avoid future self-recrimination or social regret.

Insurance and Retirement Planning: Consumers may over-insure or adopt overly conservative strategies in retirement to prevent regret from unforeseen adverse events, even if those strategies are suboptimal in expected value terms.

Criticism and Limitations

While Regret Theory offers important insights into actual behavior, it also faces some challenges. Critics argue that the theory lacks predictive precision because the regret function is often unspecified or difficult to quantify. Additionally, it requires assumptions about how individuals forecast and weigh hypothetical outcomes, which can vary widely.

Empirical testing of Regret Theory is also more complex than that of traditional utility models because it requires data on counterfactual outcomes. Furthermore, the inclusion of psychological factors increases the descriptive power of the model but reduces its normative clarity, making it harder to prescribe optimal behavior.

The Bottom Line

Regret Theory is a behavioral model that incorporates the emotional response of regret into economic decision-making. It explains deviations from expected utility theory by suggesting that people seek to minimize anticipated regret rather than maximize calculated utility. This theory has significant relevance in finance, particularly in understanding investor behavior, portfolio construction, and behavioral biases. While it enriches the analysis of decision-making under uncertainty, its subjective and sometimes imprecise nature limits its use as a strict predictive tool.