The right temporo-parietal junction (rTPJ) is thought to be closely related to theory of mind (ToM) and cognitive empathy. In the present study, we investigated whether these socio-cognitive abilities could be modulated with non-invasive transcranial direct current stimulation (tDCS) of the rTPJ. Participants received anodal (excitatory), cathodal (inhibitory), or sham stimulation before performing a social cognitive task which included inferring other’s intention (the ToM condition) and inferring other’s emotion (the cognitive empathy condition). Our results showed that the accuracy of both ToM and cognitive empathy decreased after receiving the cathodal stimulation, suggesting that altering the cortical excitability in the rTPJ could influence human’s socio-cognitive abilities. The results of this study emphasize the critical role of the rTPJ in ToM and cognitive empathy and demonstrate that these socio-cognitive abilities could be modulated by the tDCS.

Social value orientation (SVO) is a stable personality trait that reflects how people evaluate interdependent outcomes for themselves and others in social environments. Generally, people can be classified into two types: proselfs and prosocials. The present study examined how SVO affects the processing of outcome evaluation temporally using the event-related potential (ERP). Young adults with two different SVO types participated in a simple gambling task in which they received outcome distributions for themselves and others. The results showed that for the self outcomes, the feedback-related negativity (FRN) was more negative for self-loss than self-gain, and the P3 and late positive component (LPC) was larger for self-gain than self-loss in both prosocial and proself groups. For the other outcomes, however, the FRN, P3 and LPC were sensitive to other’s gain and loss only in the prosocial group but not in the proself group. These findings suggest that outcomes for oneself and others are processed differently at different stages of evaluation processing in the brains of individuals with distinct SVOs.

Social value orientation (SVO) characterizes stable individual differences by an inherent sense of fairness in outcome allocations. Using the event-related potential (ERP), this study investigated differences in fairness decision-making behavior and neural bases between individuals with prosocial and proself orientations using the Ultimatum Game (UG). Behavioral results indicated that prosocials were more prone to rejecting unfair offers with stronger negative emotional reactions compared with proselfs. ERP results revealed that prosocials showed a larger P2 when receiving fair offers than unfair ones in a very early processing stage, whereas such effect was absent in proselfs. In later processing stages, although both groups were sensitive to fairness as reflected by an enhanced medial frontal negativity (MFN) for unfair offers and a larger P3 for fair offers, prosocials exhibited a stronger fairness effect on these ERP components relative to proselfs. Furthermore, the fairness effect on the MFN mediated the SVO effect on rejecting unfair offers. Findings regarding emotional experiences, behavioral patterns, and ERPs provide compelling evidence that SVO modulates fairness processing in social decision-making, whereas differences in neural responses to unfair vs. fair offers as evidenced by the MFN appear to play important roles in the SVO effect on behavioral responses to unfairness.

Neural responses to others' decision-making outcomes can be modulated by many social factors. Using the event-related potential (ERP) technique, we explored the neural mechanisms of empathic concern modulating evaluative processing of others' outcomes. Participants were asked to perform a gambling task for three beneficiaries: themselves and two strangers. One stranger was an economically underprivileged student requiring help (high-empathy condition); the other stranger was a student with no upsetting information to induce empathic concern (low-empathy condition). ERP results showed that the valence effect of the feedback-related negativity (FRN) was larger when participants exhibited high empathic concern than when they did not. The FRN responses to strangers' outcomes in the high-empathy condition were as strong as those to their own outcomes. The P300 showed no differences between the low-and high-empathy conditions. These findings indicate that empathic concern could modulate the early stage of outcome processing, implying empathic emotional/altruistic motivational impacts of others' outcomes.

Empathy plays a central role in social decisions involving psychological conflict, such as whether to help another person at the cost of one’s own interests. Using the event-related potential (ERP) technique, the current study explored the neural mechanisms underlying the empathic effect on the evaluation processing of outcomes in conflict-of-interest situations, in which the gain of others resulted in the performer’s loss. In the high-empathy condition, the beneficiaries were underprivileged students who were living in distress (stranger in need). In the low-empathy condition, the beneficiaries were general students without miserable information (stranger not in need). ERP results showed that the FRN was more negative-going for self no-gain than self gain, but showed reversed pattern for other’s outcome (i.e., more negative for gain than no-gain) in the low-empathy condition, indicating that participants interpreted the gain of others as the loss of themselves. However, the reversed FRN pattern was not observed in the high-empathy condition, suggesting that the neural responses to one’s own loss are buffered by empathy. In addition, the P3 valence effect was observed only in the self condition, but not in the two stranger conditions, indicating that the P3 is more sensitive to self-relevant information. Moreover, the results of subjective rating showed that more empathic concern and altruistic motivation were elicited in the high-empathy condition than in the low-empathy condition, and these scores had negative linear correlations only with the FRN, but not with the P3. These findings suggest that when outcomes following altruistic decisions involve conflict of interest, the early stage of the processing of outcome evaluation could be modulated by the empathic level.