The impact of social distance on the processing of social evaluation: evidence from brain potentials and neural oscillations.

Previous research indicates that social distance can influence people's social evaluations of others. Individuals tend to evaluate intimate others more positively than distant others. The present study investigates the modulating effect of social distance on the time course underlying individuals' evaluation processes of others using adequate electroencephalography methods. The results reveal that in the initial processing stage, the P2 component is larger when friends are negatively evaluated, whereas this pattern is the opposite for strangers. In the second stage, medial frontal negativity and early mid-frontal theta band activity is enhanced for negative evaluations of friends, whereas this effect is absent in social evaluations of strangers. At the late stage, the P3 is larger for positive evaluations of friends but insensitive to social evaluations of strangers, and the late mid-frontal theta is also modulated by social distance. These findings provide direct and powerful evidence that social distance modulates individuals' evaluations of others with different levels of intimacy throughout all processing stages.

Effects of transcranial direct current stimulation over the right dorsolateral prefrontal cortex on fairness-related decision-making.

Neuroimaging studies suggest that the right dorsolateral prefrontal cortex (rDLPFC) is an important brain area involved in fairness-related decision-making. In the present study, we used transcranial direct current stimulation (tDCS) over the rDLPFC to investigate the effects of changed cortical excitability on fairness norm enforcement in social decision-making. Participants received anodal, cathodal or sham stimulation before performing a modified ultimatum game task, in which participants were asked to accept or reject the proposer's offer and self-rate the intensity of their anger at offers on a 7-point scale. The results showed that the rejection rate of unfair offers and anger level were higher in the anodal compared to the sham and cathodal groups and that the level of anger at unfair offers can predict the rejection rate. Furthermore, the fairness effect of RTs was more prominent in the anodal group than in the sham and cathodal groups. Our findings validate the causal role of the rDLPFC in fairness-related decision-making through tDCS, suggesting that strengthening the rDLPFC increases individuals' reciprocal fairness in social decision-making, both in subjective rating and behaviors.

Social value orientation modulates fairness processing during social decision-making: evidence from behavior and brain potentials.

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.

Social distance modulates outcome processing when comparing abilities with others.

Social comparison occurs when individuals evaluate themselves in comparison with others. Social distance can influence the effect of social comparison. Using event-related potentials, this study examined how social distance affects the time course of outcome processing when individuals compare themselves with others in terms of ability. Participants were asked to perform a dot estimation task with a friend and a stranger. The results showed the effect of social distance on the N1, feedback-related negativity (FRN), and P300, such that the N1 and P300 were greater for the outcome when pairing with the stranger than when pairing with the friend, whereas the FRN was more negative for the outcome when pairing with the friend than when pairing with the stranger, suggesting that participants allocated more attention resources to the stranger's outcome during the early, automatic (the N1) and later, controlled processing stage (the P300). In addition, the FRN was sensitive to the valence of both self- and other-outcomes, and the FRN valence effect of self-outcome was modulated by friends' outcomes but not by strangers' outcomes, indicating that at the semi-automatic processing stage, closer social distance increases the likelihood of individuals being affected by the comparison targets. These results suggest that when comparing with others in the ability dimension, social distance plays a different role in different stages of outcome processing. At the primary stage of outcome processing, individuals are more likely to compare with close others in the ability dimension.

Your losses are mine: The influence of empathic concern on evaluative processing of others' outcomes.

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.

Increasing the Difference in Decision Making for Oneself and for Others by Stimulating the Right Temporoparietal Junction.

The right temporoparietal junction (rTPJ) has been thought to be associated with the difference in self-other decision making. In the present study, using noninvasive transcranial direct current stimulation (tDCS), we examined whether stimulating the rTPJ could modulate the self-other decision-making difference. We found that after receiving anodal stimulation of the rTPJ, participants were more likely to choose a high-value item for others than for themselves in the situations where the win probability of the high-value item was equal to or greater than that of a low-value item, indicating that elevating the cortical excitability of the rTPJ might increase the self-other decision-making difference in certain decision contexts. Our results suggest that decision making for others depends on neural activity in the rTPJ and regulation of the excitability of the rTPJ can influence the self-other decision-making difference.

The impact of trust decision-making on outcome processing: Evidence from brain potentials and neural oscillations.

It may be beneficial, although risky, to decide to trust others during social interactions in daily life. The current study explored the time course of the effect of trust decisions on outcome evaluation processing using electroencephalographic (EEG) techniques. Twenty-two healthy young adults made trust or distrust decisions regarding a message they received from a stranger in a card game. The results showed that at the early stage of outcome processing, feedback-related negativity (FRN) was more negative for losses than for gains, and more importantly, this valence effect of FRN was greater for outcomes following trust decisions than distrust decisions. At the later stage, the P3 was larger for gains than for losses and for outcomes following trust decisions than distrust decisions. In addition, at both the early and late stages, differences in the mid-frontal theta power between losses and gains were also greater in the trust condition than in the distrust condition. These findings indicate that trust decisions could effectively modulate the processing of outcome evaluation at different stages. The trust effect at the early stage of outcome processing suggests that compared to distrust decisions, trust decisions result in greater motivation and expectancy to obtain positive outcomes. While the trust effect on the later stage of outcome processing suggests that individuals pay more attention and feel stronger emotional experience to the outcomes following trust decisions. This study sheds light on the neural mechanisms of trust decisions modulating outcome processing.

Empathy Modulates the Evaluation Processing of Altruistic 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.

Social value orientation modulates the processing of outcome evaluation involving others.

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.

Using tDCS to Explore the Role of the Right Temporo-Parietal Junction in Theory of Mind and Cognitive Empathy.

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.