This paper reports an experimental test of how individuals learn from the behavior of others. By using techniques only available in the laboratory, we elicit subjects' beliefs. This allows us to distinguish informational cascades from herd behavior. By adding a setup with continuous signal and discrete action, we enrich the ball-and-urn observational learning experiments paradigm of Anderson and Holt (1997). We attempt to understand subjects' behavior by estimating a model that allows for the possibility of errors in earlier decisions. (JEL C92, D8).

The analysis explores Bayes-rational sequential decision making in a game with pure information externalities, where each decision maker observes only her predecessor's binary action. Under perfect information the martingale property of the stochastic learning process is used to establish convergence of beliefs and actions. Under imperfect information, in contrast, beliefs and actions cycle forever. However, despite the instability, over time the private information is ignored and decision makers become increasingly likely to imitate their predecessors. Consequently, we observe longer and longer periods of uniform behavior, punctuated by increasingly rare switches. These results suggest that imperfect information premise provides a better theoretical description of fads and fashions. (JEL D82, D83). * We are grateful to Douglas Gale for his guidance, to an Associate Editor and an anonymous referee for their comments and to William J. Baumol who read carefully through the manuscript, and made invaluable suggestions on exposition. We also acknowledge helpful discussions of Jean

Social learning describes any situation in which individuals learn by observing the behavior of others. In the real world, however, individuals learn not just by observing the actions of others but also from seeking advice. This paper introduces advice giving into the standard social-learning experiment of Çelen and Kariv (Çelen, B., S. Kariv. 2005. An experimental test of observational learning under imperfect information. Econom. Theory 26(3) 677-699). The experiments are designed so that both pieces of information--action and advice--are equally informative (in fact, identical) in equilibrium. Despite the informational equivalence of advice and actions, we find that subjects in a laboratory social-learning situation appear to be more willing to follow the advice given to them by their predecessor than to copy their action, and that the presence of advice increases subjects' welfare.experiment, naïve advice, social learning, word-of-mouth learning

Nearly all observational learning models assume that individuals can observe all the decisions that have previously been made. In reality, such perfect information is rarely available. To explore the difference between observational learning under perfect and imperfect information, this paper takes an experimental look at a situation in which individuals learn by observing the behavior of their immediate predecessors. Our experimental design uses the procedures of Çelen and Kariv [9] and is based on the theory of Çelen and Kariv [10]. We find that imitation is much less frequent when subjects have imperfect information, even less frequent than the theory predicts. Further, while we find strong evidence that under perfect information a form of generalized Bayesian behavior adequately explains behavior in the laboratory, under imperfect information behavior is not consistent even with this generalization of Bayesian behavior. Copyright Springer-Verlag Berlin/Heidelberg 2005Asymmetric information, Herd behavior, Informational cascades, Imperfect information, Experimental economics.,

This paper analyzes the incentive implications of executive hedge markets. The manager can promise the return from his shares to third parties in exchange for a fixed payment-swap contracts-and/or he can trade a customized security correlated with his firm-specific risk. The customized security improves incentives by diversifying the manager's firm-specific risk. However, unless they are exclusive, swap contracts lead to a complete unraveling of incentives. When security customization is sufficiently high, the manager only trades the customized security-but not any nonexclusive swap contracts, and incentives improve. Access to highly customized hedge securities and/or exclusive swap contracts increases the manager's pay-performance sensitivity.