Enrico Diecidue

Aspiration Level, Probability of Success and Failure, and Expected Utility

Aspiration levels are a relevant aspect of decision making. We develop a model that includes the overall probabilities of success and failure relative to the aspiration level into an expected utility representation. This turns out to be equivalent to expected utility with a discontinuous utility function. We give a behavioral foundation to the proposed model and provide conditions to determine the relative weights of the overall probabilities of success and failure. An aspiration level reinforces loss aversion, can account for simultaneous risk-averse and risk-seeking behavior, and can explain choices violating the mean-variance approach.

A Quantitative Measurement of Regret Theory

This paper introduces a method to measure regret theory, a popular theory of decision under uncertainty. Regret theory allows for violations of transitivity, and it may seem paradoxical to quantitatively measure an intransitive theory. We adopt the trade-off method and show that it is robust to violations of transitivity. Our method makes no assumptions about the shape of the functions reflecting utility and regret. It can be performed at the individual level, taking account of preference heterogeneity. Our data support the main assumption of regret theory, that people are disproportionately averse to large regrets, even when event-splitting effects are controlled for. The findings are robust: similar results were obtained in two measurements using different stimuli. The data support the reliability of the trade-off method: its measurements could be replicated using different stimuli and were not susceptible to strategic responding.

The Utility of Gambling Reconsidered

The utility of gambling, which entails an intrinsic utility or disutility of risk, has been alluded to in the economics literature for over a century. This paper demonstrates that any utility of gambling almost unavoidably implies a violation of fundamental rationality properties, such as transitivity or stochastic dominance, for static choices between gambles. This result may explain why the utility of gambling, a phenomenon so widely discussed, has never been formalized in the economics literature. The model of this paper accommodates well-known deviations from expected utility, such as the Allais paradox and the coexistence of gambling and insurance, while minimally deviating from expected utility.

Parametric Weighting Functions

This paper provides preference foundations for parametric weighting functions under rank-dependent utility. This is achieved by decomposing the independence axiom of expected utility into separate meaningful properties. These conditions allow us to characterize rank-dependent utility with power and exponential weighting functions. Moreover, by allowing probabilistic risk attitudes to vary within the probability interval, a preference foundation for rank-dependent utility with parametric inverse-S shaped weighting function is obtained.

Coherence without additivity

The Dutch book argument is a coherence condition for the existence of subjective probabilities. This paper gives a general framework of analysis for this argument in a nonadditive probability setting. Particular cases are given by comonotonic and affinely related Dutch books that lead to Choquet expectation and Min expectations.

Risk Preferences at Different Time Periods: An Experimental Investigation

Intertemporal decision making under risk involves two dimensions: time preferences and risk preferences. This paper focuses on the impact of time on risk preferences, independent of the intertemporal trade-off of outcomes, i.e., time preferences. It reports the results of an experimental study that examines how delayed resolution and payment of risky options influence individual choice. We used a simple experimental design based on the comparison of two-outcome monetary lotteries with the same delay. Raw data clearly reveal that subjects become more risk tolerant for delayed lotteries. Assuming a prospect theory--like model under risk, we analyze the impact of time on utility and decision weights, independent of time preferences. We show that the subjective treatment of outcomes (i.e., utility) is not significantly affected by time. In fact, the impact of time is completely absorbed by the probability weighting function. The effect of time on risk preferences was found to generate probabilistic optimism resulting in a higher risk tolerance for delayed lotteries. This paper was accepted by Teck Ho, decision analysis.

Dutch books: avoiding strategic and dynamic complications, and a comonotonic extension

Abstract This paper formalizes de Finetti’s book-making principle as a static individual preference condition. It thus avoids the confounding strategic and dynamic effects of modern formulations that consider games with sequential moves between a bookmaker and a bettor. This paper next shows that the book-making principle, commonly used to justify additive subjective probabilities, can be modified to agree with nonadditive probabilities. The principle is simply restricted to comonotonic subsets which, as usual, leads to an axiomatization of rank-dependent utility theory. Typical features of rank-dependence such as hedging, ambiguity aversion, and pessimism and optimism can be accommodated. The model leads to suggestions for a simplified empirical measurement of nonadditive probabilities.

Group Decisions Under Ambiguity: Convergence to Neutrality

This paper focuses on decisions under ambiguity. Participants in a laboratory experiment made decisions in three different settings: (a) individually, (b) individually after discussing the decisions with two others, and (c) in groups of three. We show that groups are more likely to make ambiguity-neutral decisions than individuals, and that individuals make more ambiguity-neutral decisions after discussing the decisions with others. This shift toward higher ambiguity neutrality in groups and after a group discussion is associated with a reduction in the rates of both ambiguity aversion and ambiguity seeking. We suggest that the results might be driven by effective and persuasive communication that takes place in groups.

Dynamic Purchase Decisions Under Regret: Price and Availability

We model a dynamic purchase context in which a consumer is uncertain about the products valuation. The consumer has two purchase opportunities for the product: forward purchase in Period 1 or spot purchase in Period 2. Two forms of regret are considered: buyers regret over the money paid in excess of his valuation of the product when buying forward and hesitaters regret for the lost opportunity of an increased surplus when not buying forward. We illustrate how regrets affect the purchase decision: a consumer is more likely to buy forward when more averse to hesitaters regret but more likely to delay the decision when more averse to buyers regret. We also consider alternative consumer types to characterize how regret affects their spot purchase decisions as well as what triggers the regret. We show that type inconsistency---that is, a consumers incorrect anticipation of his future type---induces an inferior Period 1 purchase decision and thereby reduces the consumers expected surplus.

Aspiration Levels and Preference for Skewness in Choice Under Risk

This paper describes an experiment designed to study the effect of aspiration levels on individual choices under risk.We observe preferences for prospects that offer various probabilities of achieving aspiration levels; the resulting choice patterns characterize a heuristic for reducing the complexity of risky decisions.In cases where aspiration levels are not predictive, choices can be explained by preferences for positive skewness. Our results confirm the efficacy of a two-pronged approach that includes both compensatory and simplifying strategies for choosing among risky prospects. Of the former strategies, cumulative prospect theory best fits our experimental data.