This collaborative proposal explores the effects of replacing standard probabilities or chance lotteries by uncertain beliefs in the definition of the prospects. The comparison of attitudes about prospects in which outcomes are determined by chance or by the decision maker's knowledge will provide information about the role of personal responsibility in choice. Second the project investigates cumulative decision making, that is, a series of choices in which outcomes accumulate in the course of the session. A new experimental paradigm will be developed and applied to study effects of the amount at stake, mental accounting, previous success and failures and other issues, in the context of cumulative decision making. By introducing genuine uncertainty and multiple decisions, as well as learning and feedback, this project aims to bring decision research closer to the actual practice of decisions, which typically innvolve unquantified uncertainty and are generally made in the context of other decisions.