Behavioral and Brain Sciences

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Base-rate respect: From ecological rationality to dual processes

Aron K. Barbeya1 and Steven A. Slomana2

a1 Cognitive Neuroscience Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892-1440,

a2 Cognitive and Linguistics Science, Brown University, Providence, RI 02912,


The phenomenon of base-rate neglect has elicited much debate. One arena of debate concerns how people make judgments under conditions of uncertainty. Another more controversial arena concerns human rationality. In this target article, we attempt to unpack the perspectives in the literature on both kinds of issues and evaluate their ability to explain existing data and their conceptual coherence. From this evaluation we conclude that the best account of the data should be framed in terms of a dual-process model of judgment, which attributes base-rate neglect to associative judgment strategies that fail to adequately represent the set structure of the problem. Base-rate neglect is reduced when problems are presented in a format that affords accurate representation in terms of nested sets of individuals.

Aron Barbey is a doctoral student of Lawrence W. Barsalou in the Cognition and Development Program at Emory University. His research addresses the cognitive and neural bases of human learning and inference. Upon graduation, he will join the Cognitive Neuroscience Section of the National Institute of Neurological Disorders and Stroke as a post-doctoral fellow under the supervision of Jordan Grafman.

Steven Sloman is Professor of Cognitive and Linguistic Sciences at Brown University. He is the author of Causal Models: How People Think About the World and Its Alternatives (Oxford University Press, 2005). He has also authored numerous publications in the areas of reasoning, categorization, judgment, and decision making.