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...

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

This paper discusses models of choice under imprecise objective proba- bilistic 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 systemati-...

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...

This paper reports the results of experiments testing prevalence of non-neutral ambiguity attitudes and how these attitudes change as a result of interpersonal interactions. To address the first question we conducted experiments involving individual choice between betting on ambiguous and...

Experimental results on the Ellsberg paradox typically reveal behavior that is commonly interpreted as ambiguity aversion. The experiments reported in the current paper find the objective probabilities for drawing a red ball that make subjects indifferent between various risky and uncertain...

We consider two plausible and even natural examples of ambiguity aversion: the classical Ellsberg (1961) two-color paradox and a variant of the Machina (2009) reflection example. We extend the results of Baillon et al. (2011) and demonstrate that these two examples challenge the descriptive...

We axiomatize a model of decision under objective ambiguity or imprecise risk. The decision maker forms a subjective (non necessarily additive) belief aboutthe likelihood of probability distributions and computes the average expected utility of a given act with respect to this second order...