Results of experiments designed to test the claim of psychologists that expected utility theory does not provide a good descriptive model are reported. The deviation from tested theory is that, in revising beliefs, individuals ignore prior or base-rate information contrary to Bayes rule. Flaws in the evidence in the psychological literature are noted, an experiment avoiding these difficulties is designed and carried out, and the psychologists' predictions are stated in terms of a more general model. The psychologists' predictions are confirmed for inexperienced or financially unmotivated subjects, but for others the evidence is less clear.

A wide variety of economic models include as explanatory variables either expectational variables or variables representing the result of some decision-making process. The first category includes both expectations about the future values of variables, e.g., next period's sales, the level of unemployment two quarters ahead, etc. and other subjective variables such as permanent income or the "normal" level of prices and interest rates. Examples of the second type are "desired" capital stock, planned production, or inventory accumulation, and so on.

A social choice function is said to be implementable if and only if there exists a game form such that for all preference profiles an equilibrium strategy n-tuple exists and any equilibrium strategy n-tuples of the game yield outcomes in the social choice set. A social choice function is defined to be minimally democratic if and only if whenever there exists an alternative which is ranked first by n − 1 voters and is no lower than second for the last voter, then the social choice must be uniquely that alternative. No constraints are placed on the social choice function for other preference profiles. Using the classical definitions of equilibria for n-person games—namely Nash and strong equilibria, it is shown here that over unrestricted preference domains, as long as there are at least as many alternatives as individuals, no minimally democratic social choice function is implementable. A similar result holds in certain restricted domains of the type assumed by economists over public goods spaces. We then show that a different notion of equilibrium—namely that of sophisticated equilibrium—allows for implementation of democratic social choice functions also having further appealing properties.

This paper contains a generalization of the General Possibility Theorem to situations where choice over two-element (more generally, “small”) sets is not possible. The analysis is developed in terms of the social choice function formulation rather than the social welfare function approach. In this formulation, assumptions concerning the size of sets of feasible alternatives are explicit, allowing the role of these assumptions in inducing impossibility results to be explored.

This paper reports experimental tests of three search equilibrium models. These models which differ only in the search strategies available to the buyers have qualitatively different predictions, that is, equilibria: price distributions, single price equilibria at the competitive price and at the monopoly price and two price equilibria. The experimental outcomes generally were consistent with the models' predictions. This suggests that debate on the utility of this class of models should shift to the realism of the models' assumptions rather than focus on their ability to characterize market outcomes. Also, since the basic models have been validated, the project of analysing experimentally the results of relaxing some of their assumptions seems worthwhile.

John A. Ferejohn, David M. Grether, Steven A. Matthews, Edward W. Packel; Continuous-Valued Binary Decision Procedures, The Review of Economic Studies, Vol