I work on decision making under ambiguity, that is I study behaviour of decision makers whose preferences cannot be modelled within Savage’s subjective expected utility theory. In one of my projects “Hierarchy of Ambiguity Aversion” I aim to unify two leading definitions of ambiguity aversion. A by-product is the axiomatization of so called exact capacities. In another project “A Definition of Perceived Ambiguity” I propose a new way of measuring perceived ambiguity in the multiple prior model and I apply my theory to normal-form games.