Neural mechanism underlying risk attitude and probability distortion: One two-stage model of valuation and choice

摘要

Although the neural mechanism underlying risk decision has been extensively investigated, the neural origination of risk attitude and probability distortion need to be further elucidated. In this study, the Rescorla-Wagner model with learning rates a,/a_ upon gain/loss evaluates the risky outcome and forms the subjective values of risky options through the learning process, and the softmax function of subjective values produces the choice probability between options. Our model demonstrates that risk attitude is determined by the undervaluation/overvaluation of risky outcome, the standard deviation of the subjective value, and the discrimination ability between subjective value. Our model further displays that overweighting/underweighting of small probabilities results from asymmetric learning rates and the discrimination ability between subjective value. These findings suggest that risk attitude and probability distortion share a common neural mechanism. (C) 2019 The Author(s). Published by Elsevier B.V.