Neuronal Distortions of Reward Probability without Choice
Reward probability crucially determines the value of outcomes. A basic phenomenon, defying explanation by traditional decision theories, is that people often overweigh small and underweigh large probabilities in choices under uncertainty. However, the neuronal basis of such reward probability distortions and their position in the decision process are largely unknown. We assessed individual probability distortions with behavioral pleasantness ratings and brain imaging in the absence of choice. Dorsolateral frontal cortex regions showed experience dependent overweighting of small, and underweighting of large, probabilities whereas ventral frontal regions showed the opposite pattern. These results demonstrate distorted neuronal coding of reward probabilities in the absence of choice, stress the importance of experience with probabilistic outcomes and contrast with linear probability coding in the striatum. Input of the distorted probability estimations to decision-making mechanisms are likely to contribute to well known inconsistencies in preferences formalized in theories of behavioral economics.
Additional Information© 2008 Society for Neuroscience. Received June 23, 2008; revised Aug. 21, 2008; accepted Sept. 29, 2008. This work was supported by the Wellcome Trust, the Swiss National Science Foundation, the Roche Research Foundation, and the Greek Government Scholarship Foundation. R.J.D. and W.S. are supported by Wellcome Trust Programme grants and W.S. by a Wellcome Trust Principal Research Fellowship. We thank Chris Burke and Martin Kocher for comments.
Published - TOBjns08.pdf
Supplemental Material - TOBjns08suppfig.pdf
Supplemental Material - TOBjnssupp1.pdf