Disappointment theory
We feel choices not just by their outcomes but by how they fall short of, or beat, our expectations.
What it means
Disappointment theory is a model of decision-making under risk in which the utility of an outcome depends not only on the outcome itself but on how it compares with a prior expectation, typically the expected value of the chosen gamble. Outcomes that fall below the expectation generate disappointment, which subtracts from utility, while outcomes that exceed it produce elation, which adds to it, and these emotional adjustments are anticipated and factored into the original choice. Because people foresee how let down or thrilled they will feel, they may avoid gambles with a high chance of falling short of a tempting prospect, even at some cost in expected value. The theory was developed to explain systematic violations of expected-utility theory—such as certain risk attitudes and the appeal of long shots and sure things—using a reference point set by expectations rather than, as in prospect theory, by the status quo. It is a sibling of regret theory, with disappointment keyed to the outcomes one's own choice could have produced rather than to forgone alternatives. It matters for understanding how anticipated emotion shapes risky choice.
How the model is built
Bell's 1985 version splits the value of a risky outcome into two parts: the basic utility of the money itself, and a disappointment term that depends on the gap between that outcome and a prior expectation, usually the gamble's expected value. Below the reference point the gap subtracts utility; above it, the same gap adds elation. Because the reference is the mean, a gamble with one large prize and many small ones sets a high bar that most outcomes fall under, so the small prizes sting. A decision-maker who anticipates this discounts such gambles in advance, paying an expected-value premium to avoid the foreseeable letdown. The emotion is priced into the choice, not merely felt afterward.
From Bell to disappointment aversion
Loomes and Sugden gave the idea an economic form in 1986; Gul axiomatized a leaner version in 1991. Gul's model adds a single parameter to expected utility and, crucially, makes the reference point endogenous: it is the certainty equivalent of the gamble itself, solved simultaneously with the valuation rather than fixed beforehand. A positive parameter means outcomes below that self-referential benchmark are down-weighted, which reproduces Allais-paradox choices and a taste for certainty. This tractability is why disappointment aversion, unlike its wordier cousins, has been imported into macro-finance, where it helps models generate the large historical equity premium that standard expected-utility investors would never demand.
What the evidence shows
Direct tests are scarce because disappointment is hard to isolate. Loomes and Sugden's 1987 experiment was purpose-built to separate it from regret, using paired gambles whose outcomes were revealed in ways that switched each emotion on or off. They found systematic choice patterns consistent with both effects, but modest in size and entangled, so no clean verdict favoring one over the other emerged. Later work by Delquié and Cillo (2006) argued the standard setup is too restrictive: drop the single prior expectation and let disappointment arise from comparison with any outcome the gamble could have delivered, and the model unifies with rank-dependent and risk-value theories. The behavioral core is well supported; the specific functional form is not settled.
Related but distinct
Disappointment is easily confused with two neighbors. Regret theory keys emotion to the outcome of the option you rejected: you feel bad because a foregone alternative would have paid more. Disappointment needs no counterfactual choice at all; the reference is what your own chosen gamble led you to expect. Prospect theory also uses a reference point, but sets it at the status quo or a framed target rather than at the mean of the very lottery being evaluated. The practical tell is where the sting comes from. Learning a different choice would have won points to regret; feeling a win was smaller than the gamble promised points to disappointment. Real decisions often carry both, which is exactly why experiments struggle to pull them apart.
Examples
Someone declines a gamble that would probably pay out modestly but might pay a fortune, partly to avoid the sting of the likely 'small win' feeling like a letdown against the dreamed-of jackpot.
Part of a lottery ticket's appeal is that no outcome can disappoint: you expect nothing, so losing costs no feeling at all and the improbable win is pure elation.
Holidaymakers rebook the reliable resort instead of the exotic trip that might be magical. Picturing the magical version in advance would make any merely pleasant week feel like a letdown.
After weeks of reading rave reviews, a buyer feels let down by a genuinely good phone: the coverage inflated their expectations so far that a solid device now lands below the flawless one they had come to picture.
A manager deliberately gives the board a conservative forecast, so a merely good quarter lands as a pleasant surprise rather than as a miss against a number everyone had already started counting on.
First described in Graham Loomes & Robert Sugden; David Bell (1985).
Key references
- Delquié, P., & Cillo, A. (2006). Disappointment without prior expectation: a unifying perspective on decision under risk. Journal of Risk and Uncertainty, 33(3), 197-215. doi.org/10.1007/s11166-006-0499-4
- Gul, F. (1991). A theory of disappointment aversion. Econometrica, 59(3), 667-686. www.jstor.org/stable/2938223
- Loomes, G., & Sugden, R. (1987). Testing for regret and disappointment in choice under uncertainty. The Economic Journal, 97(Supplement), 118-129. academic.oup.com/ej/article-abstract/97/Supplement/118/5190198
- Loomes, G., & Sugden, R. (1986). Disappointment and dynamic consistency in choice under uncertainty. The Review of Economic Studies, 53(2), 271-282. academic.oup.com/restud/article-abstract/53/2/271/1578590
- Bell, D. E. (1985). Disappointment in decision making under uncertainty. Operations Research, 33(1), 1-27. doi.org/10.1287/opre.33.1.1