Working Papers

Making the Gambler's Fallacy Disappear: The Role of Experience

Published:October 16, 2008
Paper Released:September 2008
Authors:Gregory M. Barron and Stephen Leider

Executive Summary:

The Gambler's Fallacy refers to the belief that chance is a self correcting process. The longer the random run of one outcome, the stronger the belief that the opposite outcome is due to appear. This paper asks whether the way we acquire information, by sequential experience or by simultaneous description, plays a critical role in the emergence of the bias in a binary prediction task (betting on red or black roulette outcomes, for example). The results show that the fallacy only occurs when decision makers experience outcomes over time and not when past outcomes are revealed all at once. The question is interesting since several recent papers on decisions from experience and descriptions suggest that the way people acquire information can have a significant effect on behavior. Key concepts include:

  • This paper's main contribution is in delineating a boundary condition for the emergence of a well-known cognitive bias.
  • Taken together, results suggest that qualitatively different processes are engaged when people encounter information sequentially over time.

About Faculty in this Article:

HBS Faculty Member Gregory M. Barron

Gregory M. Barron is an assistant professor in the Negotiation, Organizations and Markets unit at Harvard Business School.

Abstract

Recent papers have demonstrated that the way people acquire information about a decision problem, by experience or by abstract description, can affect their behavior. We examine the role of experience over time in the emergence of the Gambler's Fallacy in binary prediction tasks. Theories of the Gambler's Fallacy and models of binary prediction suggest that recency bias, elicited by experience over time, may be necessary for the fallacy to emerge. Experiment 1 compares a condition where participants sequentially predict the colored outcomes of a roulette wheel with a condition where the wheel's past outcomes are presented all at once. Subjects are yoked so that the same history of outcomes is observed in both conditions. The results reveals a tendency towards negative recency when outcomes are experienced that disappears when the same outcomes are presented all at once. Experiment 2 examines a boundary condition where outcomes are presented sequentially in an automatic fashion without intervening predictions. Here too, the Gambler's Fallacy emerges suggesting that it is the mere presentation of information over time that gives rise to the bias. Implications are discussed.

Paper Information