Morality recruits neural reward circuitry to shape economic decision making

Abstract

The present study combined a novel hypothetical investment game with functional magnetic resonance imaging systemtically examined how morality modulates economic decision making in decision phase and outcome phase. We manipulated the morality of the investments by choosing each investment project based on subjective ratings on their moral valence and social benefits. There were three categories of investment morality: Green (moral), Red (immoral), and Neutral. The behavioral and neural responses during the investment decision and outcome phases were recorded and compared. Results showed that: behaviorally, people are willing to invest a larger amount of money into a moral project that may benefit society than they are into an immoral project that they think will harm society. They also rate gains in moral investments as more pleasant and losses as the most unpleasant. In the brain, we found that the reward system, especially the bilateral striatum, was involved in modulating functional connectivity during both phases, but in different ways. During decision making, the functional connectivity between fusiform gyrus and striatum might underlie the observed investing bias (Green over Red projects), while the covariation of BOLD signals in bilateral striatum with the behavioral tendency might explain the effect observed during the outcome evaluations. Our study provides evidence that morality modulates both the decision making and the outcome evaluation in economic situations.