Rapid changes in risk attitudes originate from Bayesian inference on parietal magnitude representations

Risk attitudes—the willingness to accept uncertainty for larger potential rewards—are often treated as a stable individual trait, yet people’s risky choices change markedly across contexts and even across repetitions of identical decisions. Here we show, using modelling and neuroimaging, that such rapid changes emerge from Bayesian inference on noisy magnitude representations in parietal cortex. Participants underwent fMRI while choosing between safe and risky options that are either held in working memory or shown on screen.

Options held in working memory are noisier and more prone to central-tendency biases, so relatively small payoffs are overestimated and large payoffs underestimated, shifting choices between risk-seeking and risk aversion. A computational model of payoff perception captures these effects mechanistically. Numerical population-receptive-field modelling shows that when intraparietal payoff representations are noisier, choices are less consistent and less risk-neutral.

Thus, risk attitudes and their contextual variability can be rooted in perceptual inference on parietal magnitude representations. Moisa at the Zurich Center for Neuroeconomics and Roger Lüchinger at the IBT for their excellent assistance in scanning, recruitment and participant facilitation. C.C.R. received funding from the University Research Priority Program ‘Adaptive Brain Circuits in Development and Learning’ at the University of Zurich and the Swiss National Science Foundation SNSF (grants no. 100019L−173248 and 10.006.863).

G.d.H. was funded by the Dutch Research Council NWO (Rubicon grant no. 019.183SG.017) and the University of Zurich (Forschungskredit grant no. Open access funding provided by University of Zurich. Zurich Center for Neuroeconomics, Department of Economics, University of Zurich, Zurich, Switzerland Gilles de Hollander, Marcus Grueschow & Christian C.

Ruff University Research Priority Program (URPP), Adaptive Brain Circuits in Development and Learning, University of Zurich, Zurich, Switzerland UZH Healthy Longevity Center, University of Zurich, Zurich, Switzerland Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland Faculty of Medicine, University of Zurich, Zurich, Switzerland Correspondence to Gilles de Hollander or Christian C. The authors declare no competing interests. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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