Neurocomputational mechanisms at play when weighing concerns for extrinsic rewards, moral values, and social image

• Published in: PLoS biology 2019-06, Vol.17 (6), p.e3000283-e3000283
• Main Authors: Qu, Chen, Météreau, Elise, Butera, Luigi, Villeval, Marie Claire, Dreher, Jean-Claude
• Format: Article
• Language: English
• Subjects: Altruism; Animal cognition; Bernard, Claude (1813-78); Biology and Life Sciences; Brain; Brain Mapping - methods; Brain research; Computer and Information Sciences; Computer Simulation; Cortex (cingulate); Costs; Decision making; Decision Making - ethics; Decision Making - physiology; Economics; Economics and Finance; Functional magnetic resonance imaging; Gender differences; Humanities and Social Sciences; Humans; Magnetic Resonance Imaging - methods; Male; Medical imaging; Medicine and Health Sciences; Moral Obligations; Morality; Morals; Motivation; Nerve Net - physiology; Neural circuitry; Neuroimaging - methods; Neurosciences; Norms; Physiological aspects; Prefrontal cortex; Prefrontal Cortex - physiology; Putamen; Putamen - physiology; Research and Analysis Methods; Reward; Self image; Self interest; Social Sciences; Values; Weighing; Young Adult
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.3000283

Humans not only value extrinsic monetary rewards but also their own morality and their image in the eyes of others. Yet violating moral norms is frequent, especially when people know that they are not under scrutiny. When moral values and monetary payoffs are at odds, how does the brain weigh the benefits and costs of moral and monetary payoffs? Here, using a neurocomputational model of decision value (DV) and functional (f)MRI, we investigated whether different brain systems are engaged when deciding whether to earn money by contributing to a "bad cause" and when deciding whether to sacrifice money to contribute to a "good cause," both when such choices were made privately or in public. Although similar principles of DV computations were used to solve these dilemmas, they engaged 2 distinct valuation systems. When weighing monetary benefits and moral costs, people were willing to trade their moral values in exchange for money, an effect accompanied by DV computation engaging the anterior insula and the lateral prefrontal cortex (PFC). In contrast, weighing monetary costs against compliance with one's moral values engaged the ventral putamen. Moreover, regardless of the type of dilemma, a brain network including the anterior cingulate cortex (ACC), anterior insula, and the right temporoparietal junction (TJP) was more engaged in public than in private settings. Together, these findings identify how the brain processes three sources of motivation: extrinsic rewards, moral values, and concerns for image.