Modelling decision making using immediate probabilities

In this paper we provide a model of how a decision maker incorporates payoffs, event probabilities, and his level of optimism to select an alternative. We present a new decision making method that combines decision making under uncertainty with decision making under risk. We introduce a new concept of immediate probabilities for use by decision makers in selecting alternatives. We discuss the role of the decision maker's level of optimism in transforming probabilities into immediate probabilities to be used for a decision. We show how the Ordered Weighted Averaging (OWA) operators play a central role in this modification. We also provide a procedure to learn OWA structures and the decision maker's level of confidence from previous decisions and we show how this information can be used for new decisions.