Neuronal signals for reward risk and formal economic utility
Department of Physiology, Development & Neuroscience, University of Cambridge, UK
In behavioural studies on monkeys, we establish nonlinear utility functions that predict independent attitudes to different types of mathematically defined risk. The animals' stochastic choices are meaningful in following transitivity and first, second and third order stochastic dominance of the tested gambles, thus confirming rational choice behaviour governed by value, symmetric (variance) risk and skewness risk, respectively. The dopamine prediction error response codes economic utility and satisfies first- and second-order stochastic dominance. These data unite concepts from animal learning theory and economic decision theory at the level of single reward neurons.