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

Abstract

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.

Endogenous testosterone is associated with increased striatal response to audience effects during prosocial choices

“…This design allows us to investigate whether testosterone is involved in guiding prosocial vs. selfish decisions induced by the presence of an audience when participants face a moral dilemma. Because weighing monetary costs against compliance with one's moral values (Qu et al, 2019) and perceiving one's good reputation (Izuma et al, 2008(Izuma et al, , 2010 have been reported to result in striatal activity, we hypothesize a positive correlation between testosterone levels and striatal activation while making prosocial decisions in reaction to the presence of an audience.…”

“…We summarize in this section the experimental design, all the details being developed in Qu et al (2019). Twenty-four healthy male participants, aged 22.47±2.62 years, with no history of neurological or psychiatric illness participated in the fMRI experiment.…”

“…This includes the striatum, anterior cingulate cortex (ACC), ventromedial prefrontal cortex (vmPFC) and temporo-parietal junction (TPJ). This network is recruited when expecting social rewards as well as when weighing monetary costs against compliance with one's moral values, or when helping choices are made (Cutler and Campbell-Meiklejohn, 2019;Qu et al, 2019). Yet, how the aforementioned network is regulated by sex hormone is unknown, although an increasing effort has been devoted to exploring how other hormones such as estrogen and oxytocin modulate prosocial behavior (Kemp and Guastella, 2010;Zethraeus et al, 2009).…”

“…Here, we explored the relationship between endogenous testosterone levels and the neural mechanisms underlying prosocial behavior in reaction to the presence or absence of an audience. To address this question, we used the behavioral data from a donation experiment published by Qu et al (2019). In this experiment, participants had to decide whether to accept or reject monetary transfers to two organizations (one positively evaluated, and the other negatively evaluated).…”

Morality recruits neural reward circuitry to shape economic decision making

“…Another recent study exploring how the brain solves the conflict between moral value and monetary value reported that the insula and lateral prefrontal cortex engage in weighing monetary benefits and moral costs while the putamen engages in weighing monetary costs against compliance with one’s moral values. Thus, the authors suggested that reward-related regions, especially the striatum, are involved in processing both moral and economic values, and that these representations interact with each other (Qu et al, 2019). These findings indicate that reward circuitry might play a significant role in resolving the conflict between morality and economic interests.…”