to obtain an ambiguity threshold. Alternating experiments on urns and games had the dual aim of erasing the short term memory of subjects, and providing an independent measure of subjects' ambiguity-attitudes. It was found that R is chosen quite frequently by subjects. While the Row Player randomises 50:50 between her strategies, the Column Player shows a marked preference for avoiding ambiguity and choosing his ambiguity-safe strategy. Thus, the results provide evidence that ambiguity influences behaviour in the games. One surprising feature of the results was that the links between choices in the single person decision and those in the games was not strong. Subjects appeared to perceive a greater level of ambiguity in a two-person coordination game, than a single person decision problem. More generally the results suggested that perceptions of ambiguity and even attitudes to ambiguity depend on context. Hence it may not be possible to measure ambiguity-attitude in one context and use it to predict behaviour in another. Ambiguity and learning Given the salience of ambiguity in economic and financial research, it is natural to wonder about its relation with learning and its persistence over time. The long-run persistence of ambiguity clearly depends on the way the inter-temporal ambiguity is modeled. If the decision-maker incorporate new information according to a natural generalization of Bayes' rule entailing a set of priors (rather than a unique prior) on a given prior support; then Massari-Newton (2020) and Massari-Marinacci (2019) show that long-run ambiguity is not a possible outcome of the multiple prior-learning models with convex prior support (i.e., positive Lebegue measure) and provide sufficient conditions for ambiguity to fade away when the prior support is not convex, respectively. See also Ambiguity effect Ambiguity tolerance Choquet expected utility David Schmeidler Knightian uncertainty Precautionary principle Uncertainty Uncertainty avoidance References \\ Alary, D., Gollier, C. G., & Treich, N. (2010, March 15). The effect of ambiguity aversion on risk reduction and insurance demand. Retrieved from http://www.economics.unsw.edu.au/contribute2/Economics/news/documents/NicolasApri10.pdf Borghanst, L., Golstey, B. H. H., Heckman, J. J., & Meijer, H. (2009, January). Gender differences in risk aversion and ambiguity aversion. Retrieved from http://ftp.iza.org/dp3985.pdf Ghirardato, P., & Marinacci, M. (2001). Risk, Ambiguity, and the Separation of Utility and Beliefs. Mathematics of Operations Research, 26(4), 864-890. Retrieved from https://www.jstor.org/stable/3690687 Game theory Expected utility