When confronted with uncertain prospects, people often exhibit both choice deferral and Ellsberg-type ambiguity aversion. This paper obtains a joint representation for these behavioral phenomena. The decision maker as portrayed by my model is willing to choose an uncertain prospect f over g...

This paper discusses models of choice under imprecise objective probabilistic information featuring beliefs about beliefs -- second order beliefs. A new model, called Second Order Dual Expected Utility (SODEU) featuring non-additive second order beliefs is introduced, axiomatized and...

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...

We investigate what it means for one act to be more ambiguous than another. The question is evidently analogous to asking what makes one prospect riskier than another, but beliefs are neither objective nor representable by a unique probability. Our starting point is an abstract class of...

In two experiments, decision makers chose between risky and ambiguous gambles under conditions of both single (unrepeated) and multiply repeated choices. The gambles were presented either as modified Ellsberg urn choices or as marketing strategy decisions. In both experiments, decision makers...

We conduct a bibliometric analysis and review the literature of the last six decades on ambiguity aversion. Comparing trends in theoretical, experimental, and empirical contributions, our study presents the main aspects that are discussed in this literature. We show the increasing relevance of...

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...

We study the relation between ambiguity aversion and the Allais paradox. To this end, we introduce a novel definition of hedging which applies to objective lotteries as well as to uncertain acts, and we use it to define a novel axiom that captures a preference for hedging which generalizes the...

The standard Bayesian model implies that information can never have a negative value. We put this implication to the proof. Our paper provides the first test of the value (positive or negative) of information under uncertainty. We show that the "Bayesian implication" stands in conflict with the...