Status Quo Bias, Multiple Priors and Uncertainty Aversion

Motivated by the extensive evidence about the relevance of status quo bias both in experiments and in real markets, we study this phenomenon from a decision-theoretic prospective, focusing on the case of preferences under uncertainty. We develop an axiomatic framework that takes as a primitive the preferences of the agent for each possible status quo option, and provide a characterization according to which the agent prefers her status quo act if nothing better is feasible for a given set of possible priors. We then show that, in this framework, the very presence of a status quo induces the agent to be more uncertainty averse than she would be without a status quo option. Finally, we apply the model to a financial choice problem and show that the presence of status quo bias as modeled here might induce the presence of a risk premium even with risk neutral agents.Status quo bias, Ambiguity Aversion, Endowment Effect, Risk Premium

The Price of Flexibility: Towards a Theory of Thinking Aversion

The goal of this paper is to model an agent who dislikes large choice sets because of the "cost of thinking" involved in choosing from them. We take as a primitive a preference relation over lotteries of menus and impose novel axioms that allow us to separately identify the genuine preference over the content of menus, and the cost of choosing from them. Using this, we formally define the notion of thinking aversion, much in line with the definitions of risk or ambiguity aversion. We represent such preference as the difference between a monotone and affine evaluation of the content of the set and an anticipated thinking cost function that assigns to each set a thinking cost. We further extend this characterization to the case of monotonicity of the genuine rank and introduce a measure of comparative thinking aversion. Finally, we propose behavioral axioms that guarantee that the cost of thinking can be represented as the sum of the cost to find the optimal choice in a set and the cost to find out which is the optimal choice.Cost of Thinking, Contemplation Cost, Bounded Rationality, Preference Over Menus, Preference for Flexibility, Choice overload

Modeling the Change of Paradigm: Non-Bayesian Reactions to Unexpected News

Bayes' rule has two well-known limitations: 1) it does not model the reaction to zero-probability events; 2) a sizable empirical evidence documents systematic violations of it. We characterize axiomatically an alternative updating rule, the Hypothesis Testing model. According to it, the agent follows Bayes' rule if she receives information to which she assigned a probability above a threshold. Otherwise, she looks at a prior over priors, updates it using Bayes' rule for second-order priors, and chooses the prior to which the updated prior over priors assigns the highest likelihood. We also present an application to equilibrium refinement in game theory

A variation on Ellsberg

Ellsberg's experiment involved a gamble with no ambiguity (N) and a gamble where the prize that could be won is objectively known, but the winning probability depends on the (ambiguous) urn's composition (P). We extend this by including a gamble where the winning probability is objectively known, but the prize depends on the urn's composition (C), and also gambles where both the probability and the prize depend on the urn's composition, and can either be correlated positively (D) or negatively (M). Among transitive subjects who prefer N to P, 40% prefer D to N, 74% prefer D to P, 97% prefer D to M, and the modal ranking (about 39%) satisfies D<N<P,C. We show that this behavior is compatible with the Max-Min Expected Utility model if every prior in the set of priors has a high enough variance, a property that we call skeptical pessimism

Aspirations and growth: a model where the income of others acts as a reference point

We study an OLG model in which the average income of the society acts as a reference point for the agents’ utility on consumption. To model this we use the functional form developed in behavioral economics to study reference-dependence: prospect theory. We then assume that: 1) the utility function is convex in an interval before the reference point; 2) the utility function is not differentiable at the reference point, and it is steeper below than above the reference point. We argue that this reference-dependence causes the economy to admit multiple equilibria, and we show that in any of these equilibria in finite time the wealth distribution will become, and remain, either polarized or of perfect equality. We then study growth rates and show that, if we look at the equilibria with the highest growth, then the society that grows the most is the one that starts with perfect equality. If we look at the equilibria with the lowest growth for each economy, however, then the society with a small amount of initial inequality is the one that grows (strictly) the most, while a society with perfect equality is the one that grows the least. All of these growth rates are weakly higher than the growth rate of a corresponding economy without reference-dependence

Stochastic Choice and Preferences for Randomization

We conduct an experiment in which subjects face the same questions repeated multiple times, with repetitions of two types: (1) following the literature, the repetitions are distant from each other; (2) in a novel treatment, the repetitions are in a row, and subjects are told that the questions will be repeated. We find that a large majority of subjects exhibit stochastic choice in both cases. We discuss the implications for models of stochastic choice

Are conservatives overconfident?

Recent studies suggest psychological differences between conservatives and liberals, including that conservatives are more overconfident. We use a behavioral political economy model to show that while this is undoubtedly true for election years in the current era, there is no reason to believe that conservative ideologies are intrinsically linked to overconfidence. Indeed, it appears that in 1980 and before, conservatives and liberals were equally overconfident

Allais, Ellsberg, and preferences for hedging

Two of the most well known regularities observed in preferences under risk and uncertainty are ambiguity aversion and the Allais paradox. We study the behavior of an agent who can display both tendencies simultaneously. We introduce a novel notion of preference for hedging that applies to both objective lotteries and uncertain acts. We show that this axiom, together with other standard ones, is equivalent to a representation in which the agent (i) evaluates ambiguity using multiple priors, as in the model of Gilboa and Schmeidler, 1989, and (ii) evaluates objective lotteries by distorting probabilities, as in the rank dependent utility model, but using the worst from a set of distortions. We show that a preference for hedging is not sufficient to guarantee Ellsberg-like behavior if the agent violates expected utility for objective lotteries; we provide a novel axiom that characterizes this case, linking the distortions for objective and subjective bets

Objective Lotteries as Ambiguous Objects: Allais, Ellsberg, and Hedging

We derive axiomatically a model in which the Decision Maker can exhibit simultaneously both the Allais and the Ellsberg paradoxes in the standard setup of Anscombe and Aumann (1963). Using the notion of ‘subjective’, or ‘outcome’ mixture of Ghirardato et al. (2003), we define a novel form of hedging for objective lotteries, and introduce a novel axiom which is a generalized form of preferences for hedging. We show that this axiom, together with other standard ones, is equivalent to a represen- tation in which the agent reacts to ambiguity using multiple priors like the MaxMin Expected Utility model of Gilboa and Schmeidler (1989), generating an Ellsberg-like behavior, while at the same time, she treats also objective lotteries as ‘ambiguous objects,’ and use a fixed (and unique) set of priors to evaluate them – generating an Allais-like behavior. We show that this representation is equivalent to one in which the agent evaluates lotteries using a set of concave rank-dependent utility functionals. A comparative notion of preference for hedging is also introduced

Stochastic Choice and Preferences for Randomization

We conduct an experiment to investigate the origin of stochastic choice and to differentiate between the three main classes of models that account for it: Random Expected Utility; Mistakes; and Deliberate Randomization. Subjects face the same questions multiple times in two ways: 1) following the literature, with repetitions distant from each other; 2) in a novel treatment, with repetitions in a row, telling subjects that questions will be repeated. A large majority of subjects exhibited stochastic choice in both cases, and stochasticity is strongly correlated in the two cases. Our results support the class of models of Deliberate Randomization