Risky decision making for others is ubiquitous in our societies. Whereas financial decision making for oneself induces strong concern about the worst outcome (maximin concern) as well as the expected value, behavioral and neural characteristics of decision making for others are less well understood. We conducted behavioral and functional magnetic resonance imaging (fMRI) experiments to examine the neurocognitive underpinnings of risky decisions for an anonymous other, using decisions for self as a benchmark. We show that, although the maximin concern affected both types of decisions equally strongly, decision making for others recruited a more risk-neutral computational mechanism than decision making for self. Specifically, participants exhibited more balanced information search when choosing a risky option for others. Activity of right temporoparietal junction (rTPJ, associated with cognitive perspective taking) was parametrically modulated by options’ expected values in decisions for others, and by the minimum amounts in decisions for self. Furthermore, individual differences in self-reported empathic concern modified these attentional and neural processes. Overall, these results indicate that the typical maximin concern is attenuated in a risk-neutral direction in decisions for others as compared to self. We conjecture that, given others’ diverse preferences, deciding as a neutral party may cognitively recruit such risk-neutrality.

Charitable giving represents a unique cooperative characteristic of humans. In today's environment with social media, our charitable decisions seem to be influenced by social information such as a project's popularity. Here we report three experiments that examined people's reactions to social information about a charitable endeavor and their psychophysiological underpinnings. Participants were first solicited to make donations to either the Africa or Syria project of UNICEF. Then participants were provided an opportunity to learn social information (i.e., how much each project had raised from previous participants) and change their decision if desired. Contrary to expectation, participants who learned that their initial preferences were consistent with the majority of previous participants' choices exhibited a sizable tendency to switch to the less popular project in their final choices. This anti-conformity pattern was robust across the three experiments. Eye-tracking data (gaze bias and pupil dilation) indicated that these "Changers" were more physiologically aroused and formed more differential valuations between the two charity projects, compared to "Keepers" who retained their initial preferences after viewing the social information. These results suggest that social information about relative popularity may evoke empathic concern for the worse-off target, in line with the human tendency to avoid unequal distributions.

How much inequality should be tolerated? How should the poorest be treated? Though sometimes conflated, concerns about inequality and the fate of the poorest involve different allocation principles with different sociopolitical implications. We tested whether deliberation—the core of democracy—influences reasoning about distributive principles. 322 participants faced allocation decisions for others between egalitarian (low variance in allocation), utilitarian (high total amount), and maximin (maximizing the welfare of the poorest) options. After their initial decisions, participants either reflected upon similar decisions solely or discussed them in pairs before facing the same choices again individually. Social, but not solitary, deliberation led to more maximin and fewer egalitarian choices, and this change lasted at least 5 months after the experiment. Conversation analyses of approximately 7,500 utterances suggest that some participants initially made egalitarian choices heuristically, when in fact they mostly cared about the poorest, and dialogue promoted more internally coherent maximin preferences.

Humans dislike unequal allocations. Although often conflated, such ‘inequality-averse’ preferences are separable into two elements: egalitarian concern about the variance and maximin concern about the poorest (maximizing the minimum). Recent research has shown that the maximin concern operates more robustly in allocation decisions than the egalitarian concern. However, the real-time cognitive dynamics of allocation decisions are still unknown. Here, we examined participants' choice behaviour with high temporal resolution using a mouse-tracking technique. Participants made a series of allocation choices for others between two options: a ‘non-Utilitarian option’ with both smaller variance and higher minimum pay-off (but a smaller total) compared with the other ‘Utilitarian option’. Choice data confirmed that participants had strong inequality-averse preferences, and when choosing non-utilitarian allocations, participants' mouse movements prior to choices were more strongly determined by the minimum elements of the non-Utilitarian options than the variance elements. Furthermore, a time-series analysis revealed that this dominance emerged at a very early stage of decision making (around 500 ms after the stimulus onset), suggesting that the maximin concern operated as a strong cognitive anchor almost instantaneously. Our results provide the first temporally fine-scale evidence that people weigh the maximin concern over the egalitarian concern in distributive judgements.