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Author Notes:
Correspondence: Gregory S. Berns, Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 101 Woodruff Circle, Suite 4000, Atlanta, GA 30322; Phone: 404-727-2556; Fax: 404-727-3233; Email: gberns@emory.edu
Acknowledgments: We are grateful to Giuseppe Pagnoni and Whitney Herron for assistance and input throughout this experiment.
Subjects:
Research Funding:
Supported by grants from the National Institute on Drug Abuse (DA016434 and DA20116).
Nonlinear Neurobiological Probability Weighting Functions For Aversive Outcomes
Abstract:
While mainstream economic models assume that individuals treat probabilities objectively, many people tend to overestimate the likelihood of improbable events and underestimate the likelihood of probable events. However, a biological account for why probabilities would be treated this way does not yet exist. While undergoing fMRI, we presented individuals with a series of lotteries, defined by the voltage of an impending cutaneous electric shock and the probability with which the shock would be received. During the prospect phase, neural activity that tracked the probability of the expected outcome was observed in a circumscribed network of brain regions that included the anterior cingulate, visual, parietal, and temporal cortices. Most of these regions displayed responses to probabilities consistent with nonlinear probability weighting. The neural responses to passive lotteries predicted 79% of subsequent decisions when individuals were offered choices between different lotteries, and exceeded that predicted by behavior alone near the indifference point.
Copyright information:
© 2007 Elsevier Inc. All rights reserved.
This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported License (http://creativecommons.org/licenses/by-nc-nd/3.0/).
