Decision making behavior in a two-choice uncertain outcome situation.

The predictions people make when placed in a two-choice uncertain outcome situation have received considerable attention in recent years. In the classical situation, as first used by Humphreys (1939), S is asked to predict which of two events (e.g., illumination or nonillumination of a light) will occur after a signal stimulus. The two events occur with fixed but unequal probabilities, say TI and 7T2, in a random sequence for a number of trials, and the occurrence of either is not contingent on S's behavior. The S is instructed to do his best to predict which will occur. He is allowed to witness the event, and thus to determine for himself the correctness or incorrectness of his prediction. There are two theoretical models of interest here which yield predictions about S's behavior in a situation of this sort. One is Estes' (1950, 1954; Estes & Burke, 1953) statistical learning model which yields the prediction that Ss will learn to match their response ratios (the relative frequencies with which they predict each of the events) to the actual probabilities of occurrence of the events. The same prediction is yielded by the Bush-Mosteller (1955) model when certain restrictions are applied to the parameters of that model. A number of studies report findings in support of this prediction (Estes & Straughan,