Social signals of safety and risk confer utility and have asymmetric effects on observers' choices

Abstract

Individuals’ risk attitudes are known to guide choices about uncertain options. However, in the presence of others’ decisions, these choices can be swayed and manifest as riskier or safer behavior than one would express alone. To test the mechanisms underlying effective social ‘nudges’ in human decision-making, we used functional neuroimaging and a task in which participants made choices about gambles alone and after observing others’ selections. Against three alternative explanations, we found that observing others’ choices of gambles increased the subjective value (utility) of those gambles for the observer. This ‘other-conferred utility’ was encoded in ventromedial prefrontal cortex, and these neural signals predicted conformity. We further identified a parametric interaction with individual risk preferences in anterior cingulate cortex and insula. These data provide a neuromechanistic account of how information from others is integrated with individual preferences that may explain preference-congruent susceptibility to social signals of safety and risk.

Behavioral contagion during learning about another agent’s risk-preferences acts on the neural representation of decision-risk

“…S5B and the legend for details). Moreover, we found that, consistent with a previous study (16), mPFC and other regions tracked the utility signal incorporating the change in risk-preference across trials, but the neural effects were not associated with the behavioral shift across sessions (P > 0.05 for all of the activated clusters; Fig. S5C).…”

“…The analysis revealed that the first model provided the better fit, indicating that the behavioral shift was better explained by a change in riskpreference. Similar analyses also revealed that it is unlikely that participants simply biased utility (16) or choice probability (24) of gambling options, possibly by copying the observee's tendency to take a gamble, without changing their own risk-preference (SI Text 3 and SI Text 4). These behavioral results together suggest that decision-making under risk can be altered by observing others' decisions through the change of one's own risk-preference.…”

“…For instance, an individual's decision-making, including risk-related choice, can be changed by observing other peoples' behavior (14-18), and the behavioral shift is reflected in value-related neural activity (16,17,19). However, little is known about the computational mechanisms underlying the contagion effect.…”

The integration of social influence and reward: Computational approaches and neural evidence

“…A recent paper by Chung et al also found increased activity in the dACC when the choices of other group members were incongruent with the participant's own choice (Chung et al, 2015): this would be analogous to competing influences by the reward-based and socially-based components in our model. Here, we augment our understanding of the dACC's role in processing conflict by adding a third conflicting component: the participant's own choice history.…”

“…7) was selected: the vmPFC. This region was not revealed by our source conflict analysis, but has been implicated by previous studies to be involved in the prediction of outcomes based upon integration of multiple sources of information Boorman et al, 2013;Chung et al, 2015). Repeated measures ANOVA examined the relationship between activity in the vmPFC and the number of disagreeing sources according to the model above: the results of this analysis are shown in Supplementary Fig.…”