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

Proposer's moral identity modulates fairness processing in the ultimatum game: Evidence from behavior and brain potentials

Economic decision-making is pivotal to both human private interests and the national economy. People pursue fairness in economic decision-making, but a proposer's moral identity can influence fairness processing. Previous ERP studies have revealed that moral identity has an effect on fairness considerations in the Ultimatum Game (UG), but the findings are inconsistent. To address the issue, we revised the moral-related sentences and used the ERP technique to measure the corresponding neural mechanism. We have observed that the fairness effect in UG can be mirrored in both MFN and P300 changes, whereas the moral identity effect on fairness in UG can be reflected by MFN but not P300 changes. These findings indicate that the moral identity of the proposer can modulate fairness processing in UG. The current study opens new avenues for clarifying the temporal course of the relationship between the proposer's moral identity and fairness in economic decision-making, which is beneficial for understanding the influencing mechanism of fairness processing and fair allocations in complex social contexts.

Belief Updating during Social Interactions: Neural Dynamics and Causal Role of Dorsomedial Prefrontal Cortex

In competitive interactions, humans have to flexibly update their beliefs about another person's intentions in order to adjust their own choice strategy, such as when believing that the other may exploit their cooperativeness. Here we investigate both the neural dynamics and the causal neural substrate of belief updating processes in humans. We used an adapted prisoner's dilemma game in which participants explicitly predicted the coplayer's actions, which allowed us to quantify the prediction error between expected and actual behavior. First, in an EEG experiment, we found a stronger medial frontal negativity (MFN) for negative than positive prediction errors, suggesting that this medial frontal ERP component may encode unexpected defection of the coplayer. The MFN also predicted subsequent belief updating after negative prediction errors. In a second experiment, we used transcranial magnetic stimulation (TMS) to investigate whether the dorsomedial prefrontal cortex (dmPFC) causally implements belief updating after unexpected outcomes. Our results show that dmPFC TMS impaired belief updating and strategic behavioral adjustments after negative prediction errors. Taken together, our findings reveal the time course of the use of prediction errors in social decisions and suggest that the dmPFC plays a crucial role in updating mental representations of others' intentions.

Observing heroic behavior and its influencing factors in immersive virtual environments

Studying heroism in controlled settings presents challenges and ethical controversies due to its association with physical risk. Leveraging virtual reality (VR) technology, we conducted a three-study series with 397 participants from China to investigate heroic actions. Participants unexpectedly witnessed a criminal event in a simulated scenario, allowing observation of their tendency to physically intercept a thief. We examined situational factors (voluntariness, authority, and risk) and personal variables [gender, impulsivity, empathy, and social value orientation (SVO)] that may influence heroism. Also, the potential association between heroism and social conformity was explored. In terms of situational variables, voluntariness modulated participants' tendency to intercept the escaping thief, while perceived risk demonstrated its impact by interacting with gender. That is, in study 3 where the perceived risk was expected to be higher (as supported by an online study 5), males exhibited a greater inclination toward heroic behavior compared to females. Regarding other personal variables, the tendency to engage in heroic behavior decreased as empathy levels rose among males, whereas the opposite trend was observed for females. SVO influenced heroic behavior but without a gender interaction. Finally, an inverse relationship between heroism and social conformity was observed. The robustness of these findings was partly supported by the Chinese sample (but not the international sample) of an online study 4 that provided written descriptions of VR scenarios, indicating cultural variations. These results advance insights into motivational factors influencing heroism in the context of restoring order and highlight the power of VR technology in examining social psychological hypotheses beyond ethical constraints.

Impact of Empathic Concern on Prosocial Behavior in Gain and Loss Contexts: Evidence from Event-Related Potential

This study employs event-related potential (ERP) to examine the impact of empathic concern on prosocial decision-making with costs in both gain and loss contexts. In this experiment, participants can choose between two types of lottery tickets and pay lottery money to help the target person gain more money or lose less money. The behavioral results showed that regardless of the context of the decision (financial loss or gain), participants tended to help individuals who had induced high empathic concern. ERP results show that compared to the low-empathic-concern condition, the high-empathic-concern condition induced greater P3 amplitude in the gain context. However, this change in P3 amplitude caused by empathic concern did not occur in the context of loss. These findings indicate that empathic concern has different psychological mechanisms that moderate prosocial behavior in gain and loss contexts.

Same allocation proposed by an individual or a group elicits distinct responses: Evidence from event-related potentials and neural oscillation

People tend to perceive the same information differently depending on whether it is expressed in an individual or a group frame. It has also been found that the individual (vs. group) frame of expression tends to lead to more charitable giving and greater tolerance of wealth inequality. However, little is known about whether the same resource allocation in social interactions elicits distinct responses depending on proposer type. Using the second-party punishment task, this study examined whether the same allocation from different proposers (individual vs. group) leads to differences in recipient behavior and the neural mechanisms. Behavioral results showed that reaction times were longer in the unfair (vs. fair) condition, and this difference was more pronounced when the proposer was the individual (vs. group). Neural results showed that proposer type (individual vs. group) influenced early automatic processing (indicated by AN1, P2, and central alpha band), middle processing (indicated by MFN and right frontal theta band), and late elaborative processing (indicated by P3 and parietal alpha band) of fairness in resource allocation. These results revealed more attentional resources were captured by the group proposer in the early stage of fairness processing, and more cognitive resources were consumed by processing group-proposed unfair allocations in the late stage, possibly because group proposers are less identifiable than individual proposers. The findings provide behavioral and neural evidence for the effects of "individual/group" framing leading to cognitive differences. They also deliver insights into social governance issues, such as punishing individual and/or group violations.

Context Modulates Perceived Fairness in Altruistic Punishment: Neural Signatures from ERPs and EEG Oscillations

Social norms and altruistic punitive behaviours are both based on the integration of information from multiple contexts. Individual behavioural performance can be altered by loss and gain contexts, which produce different mental states and subjective perceptions. In this study, we used event-related potential and time-frequency techniques to examine performance on a third-party punishment task and to explore the neural mechanisms underlying context-dependent differences in punishment decisions. The results indicated that individuals were more likely to reject unfairness in the context of loss (vs. gain) and to increase punishment as unfairness increased. In contrast, fairness appeared to cause an early increase in cognitive control signal enhancement, as indicated by the P2 amplitude and theta oscillations, and a later increase in emotional and motivational salience during decision-making in gain vs. loss contexts, as indicated by the medial frontal negativity and beta oscillations. In summary, individuals were more willing to sanction violations of social norms in the loss context than in the gain context and rejecting unfair losses induced more equity-related cognitive conflict than accepting unfair gains, highlighting the importance of context (i.e., gain vs. loss) in equity-related social decision-making processes.

The impact of social hierarchies on neural response to feedback evaluations after advice giving

Advisors generally evaluate advisee-relevant feedback after advice giving. The response to these feedback-(1) whether the advice is accepted and (2) whether the advice is optimal-usually involves prestige. Prior literature has found that prestige is the basis by which individuals attain a superior status in the social hierarchy. However, whether advisors are motivated to attain a superior status when engaging in advice giving remains uncharacterized. Using event-related potentials, this study investigates how advisors evaluate feedback after giving advice to superior (vs. inferior) status advisees. A social hierarchy was first established based on two advisees (one was ranked as superior status and another as inferior status) as well as participants' performance in a dot-estimation task in which all participants were ranked as medium status. Participants then engaged in a game in which they were assigned roles as advisors to a superior or inferior status advisee. Afterward, the participants received feedback in two phases. In Phase 1, participants were told whether the advisees accepted the advice provided. In Phase 2, the participants were informed whether the advice they provided was correct. In these two phases, when the advisee was of superior status, participants exhibited stronger feedback-related negativity and P300 difference in response to (1) whether their advice was accepted, and (2) whether their advice was correct. Moreover, the P300 was notably larger when the participants' correct advice led to a gain for a superior-status advisee. In the context of advice giving, advisors are particularly motivated to attain a superior status when the feedback involving social hierarchies, which is reflected in higher sensitivity to feedback associated with superior status advisees at earlier and later stages during feedback evaluations in brains.

The influence of altruistic personality, interpersonal distance and social observation on prosocial behavior: An event-related potential (ERP) study

The psychological mechanisms that high and low altruists exhibit in different contexts remain unknown. This study examined the underlying mechanisms of the effect of altruistic personality, social observation, and interpersonal distance on prosocial behavior using event-related potentials (ERPs). Participants with high and low altruism were asked to make prosocial or non-prosocial choices toward different interpersonal distances (friends, acquaintances, or strangers) under the (non)observer condition. The electrophysiological responses to the choice stimuli were simultaneously recorded. The behavioral results demonstrated that high altruists had more prosocial choices, and these choices were unaffected by interpersonal distance and social observation. However, low altruists made more prosocial choices toward friends and acquaintances under the observer than nonobserver conditions, whereas their prosocial choices toward strangers showed no difference. The ERP results demonstrated that low altruists showed more negative N2 when the choice stimuli were toward strangers and acquaintances or under the nonobserver condition. Furthermore, low altruists showed larger P3 under the observer than nonobserver conditions when the choice stimuli were toward friends and acquaintances, while this difference was absent when the choice stimuli were toward strangers. However, for high altruists, no effect of interpersonal distance and social observation was observed in N2 and P3. These results suggest that the prosocial behavior of low altruists is mainly driven by reputational incentives, whereas high altruists are primarily motivated by concern about the well-being of others. Our findings provide insights into the prosocial behavior of high and low altruists in different contexts and support the empathy-altruism hypothesis.

The role of procedural justice and risk preference-based mechanisms in acceptance of public policy

The current study examines the relationship between procedural justice and acceptance of public policy, the mediating effect of uncertainty as well as the moderating effect of risk preference in this relationship. Study 1 conducted a questionnaire survey on 154 residents from Beijing. The results showed that risk preference moderated the effect of procedural justice on acceptance of public policy. Accordingly, Study 2 conducted a scenario experiment on 136 college students from Beijing to examine the mediating role of uncertainty, while retesting the moderating mechanism of risk preference in more detail. Results showed that risk preference significantly moderated the effect of procedural justice on acceptance of public policy. Specifically, uncertainty was more negatively associated with acceptance of public policy among the risk-averse individuals than risk-seeking individuals. Risk preference indirectly moderated the relationship between procedural justice and acceptance of public policy by moderating the relationship between uncertainty and acceptance of public policy.

Which is More Important, Proposer Identity or Allocation Motive? Event-Related Potential in Economic Decision-Making

Purpose

Most studies have supported the view that individuals prefer to reward the in-group and discriminate against the out-group in response to unfair offers in the Ultimatum Game. However, the current study advanced a different view, that is, the "black sheep effect", in which in-group members were punished more severely compared with out-group members. This study aimed to incorporate proposer identity and allocation motive as possible explanations for offer rejection.

Methods

In the current study, the in-group and out-group identities were distinguished by their health condition, and the allocation motive was defined according to its benefit maximization. With a total of 89 healthy college student participants, a mixed design of 2 (proposer identity: out-group vs in-group) × 2 (allocation motive: selfish vs random) × 2 (offer type: unfair vs fair) was used in the Ultimatum Game. Event-related potential (ERP) technology was used, and ERPs were recorded while participants processed the task.

Results

The behavioral result showed that the "black sheep effect" was found on the fair offer when a random allocation motive was used. Our ERP result suggested that feedback-related negativity (FRN) and P300 were modulated by proposer identity but not by allocation motive. However, the allocation motive interacted with proposer identity affecting FRN and P300 when the fair offer was proposed.

Conclusion

These findings demonstrated that the "black sheep effect" was related to the experience of the out-group member, such as disadvantage or distress, but it was also modulated by allocation motive. Meanwhile, the out-group (depressed college students) captured more attention because they violated individual expectations, according to the P300. This finding plays an integral role in understanding the mechanism of response to the "black sheep effect".

Social preferences trump emotions in human responses to unfair offers

People commonly reject unfair offers even if this leaves them worse off. Some explain this as a rational response based on social preferences. Others argue that emotions override self-interest in the determination of rejection behavior. We conducted an experiment in which we measured responders' biophysical reactions (EEG and EMG) to fair and unfair offers. We measured biophysical trait anger using resting-state EEG (frontal alpha-asymmetry), state anger using facial expressions, offer expectancy processing using event-related EEG (medial-frontal negativity; MFN) and self-reported emotions. We systematically varied whether rejections led proposers to lose their share (Ultimatum Game; UG) or not (Impunity Game; IG). Results favor preference-based accounts: Impunity minimizes rejection despite increasing subjectively reported anger. Unfair offers evoke frowning responses, but frowning does not predict rejection. Prosocial responders reject unfair UG offers more often after unmet fairness expectations. These results suggest that responders do not reject unfairness out of anger. Rather, people seem motivated to reject unfair offers when they violate their behavioral code but only when rejection has payoff consequences for the proposer, allowing them to reciprocate and restore equity. Thus, social preferences trump emotions when responding to unfair offers.

Distinct inter-brain synchronization patterns underlying group decision-making under uncertainty with partners in different interpersonal relationships

Humans may behave in different manners when making decisions with friends and strangers. Whether the interpersonal relationship and the characteristics of the individuals in the group affected the group decision-making under uncertainty in the real-time interaction remains unknown. Using the turn-based Balloon Analogue Risk Task (BART), the present study examined the group decision-making propensity under uncertainty with partners in different interpersonal relationships and interpersonal orientations. Corresponding inter-brain synchronization (IBS) patterns at the prefrontal cortex (PFC) were also uncovered with the fNIRS-based hyperscanning approach. Behavioral results identified that dyads in the friend group exhibited the uncertainty-averse propensity when comparing with the stranger group. The fNIRS results reported that feedback-related IBS at the left inferior frontal gyrus (l-IFG) and medial frontopolar cortex (mFPC) during different feedbacks was modulated by interpersonal relationships. The IBS at all channels in the PFC during the positive and negative feedbacks, respectively, predicted the decision-making propensity under uncertainty in the stranger and friend groups based on the support vector machine (SVM) algorithm. The moderating role of the social value orientation (SVO) was also verified in the mediation effect of the dyad closeness on the decision-making propensity under uncertainty via the IBS at the right lateral frontopolar cortex (r-FPC). These findings demonstrated disparate behavioral responses and inter-brain synchronization patterns underlying group decision-making under uncertainty with partners in different interpersonal relationships.

Role of right temporoparietal junction for counterfactual evaluation of partner's decision in ultimatum game

Humans assess the distributions of resources based on their aversion to unfairness. If a partner distributes in an unfair manner even though the partner had a less unfair distribution option, a recipient will believe that the partner should have chosen the counterfactual option. In this study, we investigated the neural basis for fairness evaluation of actual and counterfactual options in the ultimatum game. In this task, a partner chose one distribution option out of two options, and a participant accepted or rejected the option. The behavioral results showed that the acceptance rate was influenced by counterfactual evaluation (CE), among others, as defined by the difference of monetary amount between the actual and counterfactual options. The functional magnetic resonance imaging results showed that CE was associated with the right ventral angular gyrus (vAG) that provided one of convergent inputs to the supramarginal gyrus related to decision utility, which reflects gross preferences for the distribution options. Furthermore, inhibitory repetitive transcranial magnetic stimulation administered to the right vAG reduced the behavioral component associated with CE. These results suggest that our acceptance/rejection of distribution options relies on multiple processes (monetary amount, disadvantageous inequity, and CE) and that the right vAG causally contributes to CE.

Moral transgression modulates fairness considerations in the ultimatum game: Evidence from ERP and EEG data

People tend to dislike and punish unfair behaviors in social interactions, and this disposition may be moderated by the characteristics of their interaction partner. We used a modified ultimatum game (UG) to investigate players' responses to fair and unfair offers from proposers described as having performed either a moral transgression or a neutral behavior, and recorded an electroencephalogram. The participants' behavior in the UG suggests that people quickly demand more fairness from proposers who have committed moral transgressions rather than neutral behavior. Event-related potentials (ERPs) revealed a significant effect of offer type and of proposer type on P300 activity. The prestimulus α-oscillation power in the neutral behavior condition was significantly lower than that in the moral transgression condition. The post-stimulus β-event-related synchronization (β-ERS) was larger for the moral transgression condition than the neutral behavior condition in response to the least fair offers, and larger for neutral behavior than the moral transgression condition in response to the fairest offers. In summary, β-ERS was influenced by both proposer type and offer type, which revealed different neural responses to the offer from either a morally transgressive or a neutral behavior proposer.

Social distance modulates the influence of social observation on pro-environmental behavior: An event-related potential (ERP) study

Pro-environmental behavior benefits the environment but is individually costly. Therefore, understanding the neural processes of pro-environmental behavior can advance our knowledge of its implicit cost-benefit calculations and mechanisms. Previous studies have focused separately on the effects of social distance and social observation on explicit pro-environmental behavior responses, yet the underlying neurophysiological mechanism remains unknown. Using the event-related potentials (ERPs), we investigated the neural responses to the effects of social distance and social observation on pro-environmental behavior. Participants were instructed to decide between self-interest and pro-environmental choices towards different social distance targets (family members, acquaintances, or strangers) under observable and non-observable conditions. The behavioral results demonstrated that the rate of pro-environmental choices towards acquaintances and strangers was higher under the observable condition than under the non-observable condition. Nonetheless, the rate of pro-environmental choices was higher-unaffected by social observation-towards family members than towards acquaintances and strangers. The ERP results showed that the P2 and P3 amplitudes were smaller under the observable than under the non-observable condition when the potential bearers of environmental decisions were acquaintances and strangers. However, this difference did not emerge when the potential bearers of environmental decisions were family members. The ERP findings of smaller P2 and P3 amplitudes suggest that social observation may reduce the deliberate calculation of personal costs, thereby promoting individuals' pro-environmental behaviors towards acquaintances and strangers.

Interpersonal relationships modulate subjective ratings and electrophysiological responses of moral evaluations

This study explored how interpersonal relationships modulate moral evaluations in moral dilemmas. Participants rated moral acceptability in response to altruistic (prescriptive) and selfish (proscriptive) behavior conducted by allocators (i.e., a friend or stranger), toward the participants themselves or another stranger in a modified Dictator Game (Experiments 1 and 2). Event-related potential (ERP) data were recorded as participants observed the allocators' behavior (Experiment 2). Moral acceptability ratings showed that when the allocator was a friend, participants evaluated the friend's altruistic and selfish behavior toward another stranger as being less morally acceptable than when their friend showed the respective behavior toward the participants themselves. The ERP results showed that participants exhibited more negative medial frontal negativity (MFN) amplitude whether observing a friend's altruistic or selfish behavior toward a stranger (vs. participant oneself), indicating that friends' altruistic and selfish behaviors toward strangers (vs. participants) were processed as being less acceptable at the earlier and semi-automatic processing stage in brains. However, this effect did not emerge when the allocator was a stranger in subjective ratings and MFN results. In the later-occurring P3 component, no interpersonal relationship modulation occurred in moral evaluations. These findings suggest that interpersonal relationships affect moral evaluations from the second-party perspective.

Intuitive thinking impedes cooperation by decreasing cooperative expectations for pro-self but not for pro-social individuals

This study conducted two experiments to explore the effects of intuitive thinking and social value orientation (SVO) on cooperative behavior and assess the mediating effect of cooperative expectations. It manipulated intuitive thinking by increasing the participants' need for cognitive closure, classified SVO using the triple-dominance measure, measured cooperative behavior using the prisoner's dilemma game, and considered cooperative expectations based on participants' assessments of the cooperativeness of their counterparts. Both experiments showed that intuitive thinking increased and decreased the cooperation of pro-social and pro-self individuals, respectively. In pro-self individuals, cooperative expectations mediated the effect of intuitive thinking on cooperation.

The Role of Social Value Orientation in Chinese Adolescents' Moral Emotion Attribution

Previous studies have explored the role of cognitive factors and sympathy in children's development of moral emotion attribution, but the effect of personal dispositional factors on adolescents' moral emotion expectancy has been neglected. In this study, we address this issue by testing adolescents' moral emotion attribution with different social value orientation (SVO). Eight hundred and eighty Chinese adolescents were classified into proselfs, prosocials and mixed types in SVO and asked to indicate their moral emotions in four moral contexts (prosocial, antisocial, failing to act prosocially (FAP) and resisting antisocial impulse (RAI)). The findings revealed an obvious contextual effect in adolescents' moral emotion attribution and the effect depends on SVO. Prosocials evaluated more positively than proselfs and mixed types in the prosocial and RAI contexts, but proselfs evaluated more positively than prosocials and mixed types in the antisocial and FAP contexts. The findings indicate that individual differences of adolescents' moral emotion attribution have roots in their social value orientation, and suggest the role of dispositional factors in the processing of moral emotion.

The impact of social comparison and (un)fairness on upstream indirect reciprocity: Evidence from ERP

Event-related potential (ERP) technology and the dictator game paradigm are used to explore the formation mechanism of upstream indirect reciprocity behaviors. We design a within subject experiment of 3 (social comparison: upward versus parallel versus downward) × 2 (treatment: fair versus unfair) involving 49 subjects. In the first round of allocations, subjects are forced to accept a monetary amount allocated to them by another player. In the second round, subjects assume the role of allocator and divide a monetary amount between themselves and a third party. Our results show the following: 1) Having received fair treatment from someone else, individuals engaged in downward comparison are more inclined to reciprocate the fairness they had received to a third party compared to individuals in parallel and upward comparison conditions. If individuals receive unfair treatment, they tend to repeat this behavior to a third party regardless of which social comparison condition they are in; 2) Under the condition of upward comparison, individuals receiving unfair treatment exhibit greater FRN amplitude and less P300 amplitude, but in parallel and downward comparison conditions, there is no significance in FRN and P300 amplitude between individuals receiving fair and unfair treatment.

I am entitled to it! Social power and context modulate disadvantageous inequity aversion

Previous research consistently indicated that social power influences one's fairness consideration. However, it is unclear how social power and context jointly affect inequity aversion and whether these processes would be manifested in brain activities. In this study, participants were randomly assigned into either high or low power condition and then took part in a modified ultimatum game (UG) as responders in both gain and loss contexts, with their event-related potentials (ERPs) recorded. Behavioral results showed that powerful participants were more likely to reject unfair offers in both contexts compared with powerless ones. In addition, powerful participants showed a more negative feedback-related negativity (FRN) loss-win difference wave (d-FRN) upon presentation of proposed offers compared with powerless participants only in the gain context. Interestingly, in a later time window, differences of P300 responses to proposed offers were modulated by social power in both gain and loss contexts. These results suggested that powerful people were more sensitive to fairness levels and FRN may manifest fairness consideration in a gain context, but not in a loss context. Meanwhile, P300 is sensitive to fairness considerations in both gain and loss contexts.

Self-interest is intuitive during opportunity (in)equity: Evidence from multivariate pattern analysis of electroencephalography data

Fairness is a remarkable preference for human society, involving both outcome and opportunity equity. Most previous studies have explored whether fairness itself or self-interest is intuitive during outcome (in)equity. However, intuition during outcome (in)equity can be affected by both fairness level and actual payoff. Since opportunity (in)equity is only affected by the fairness level, we explored only intuition during fairness by measuring event-related potential responses to opportunity (in)equity. Participants played a social non-competitive two-person choice game with advantage opportunity inequity (AI), opportunity equity (OE), and disadvantage opportunity inequity (DI). The behavioral results suggested an opportunity inequity bias, with greater feelings of fairness and pleasantness during OE than during AI and DI. However, multivariate pattern analysis of the event-related potential (ERP) data suggested that AI, OE, and DI can be significantly distinguished from each other in relatively early windows overlapping with early positive negativity (EPN), and AI and DI can be significantly further distinguished during a relatively late window overlapping with late positive potential (LPP). Moreover, the conventional ERP analysis found that EPN amplitudes were more negative for AI than for OE and DI, as well as for OE than for DI, suggesting a pleasure bias for increased self-interest. LPP amplitudes were greater for DI than for AI and OE, suggesting enhanced sensitivity to DI. These results suggest that self-interest is intuitive during opportunity (in)equity.

The rewarding compensatory mechanism of music enhances the sense of fairness

Whether music can influence moral judgment is controversial in the aesthetics and philosophy of music. Aesthetic Autonomy pointed out that music had a morally educational function because of its lyrics or a particular context. The key to resolving the divergence is to select absolute music without lyrics or specific context as the eliciting material. In this study, 84 participants were recruited and randomly divided into three groups to complete the Ultimatum Game (UG) after listening to different stimuli: absolute music, white noise, and no sound. Behavioral results indicated that the participants’ acceptance of unfair offers was significantly lower in the music group. Also, participants in the music group have a shorter reaction time for rejecting an unfair offer than other unfair conditions. However, ERP comparison showed no significant difference in medial frontal negativity (MFN) amplitude, which reflects fairness levels, between the music group and the no sound group for either accepting or rejecting the moderately unfair offer. Brain network analyses revealed that participants in the music group showed stronger activation of rewarding circuits, including the ventral striatum, during the decision-making process of rejecting unfair offers, before the decision especially, compared to the no sound group. These results suggest that absolute music can influence fair decision-making. The reward activated by music compensates participants vicariously for the reward they receive for choosing self-interest in an unfair offer, participants no longer have to choose between self-interest and fairness norms, so the participants reject the unfair offer due to the negative emotions induced by the unfair offer.

Prosociality moderates outcome evaluation in competition tasks

The current study investigated the effect of prosociality on outcome evaluation without involving social comparison and reward processing in face-to-face competition tasks. The results showed that when faced with medium and large outcome feedback, the feedback-related negativity (FRN) amplitude induced in high-prosocial individuals was significantly more negative than that of low-prosocial individuals. In addition, the P300 amplitude induced in high-prosocial individuals was smaller than that in low-prosocial individuals in the face of large outcome feedback; hence, the prosociality score was significantly correlated with FRN amplitude. However, there was no significant difference in FRN between high-and low-prosocial individuals in the face of small outcome feedback. It was concluded that individual prosocial traits can moderate outcome evaluation.

Neural sensitivity to helping outcome predicts helping decision in real life

Prosocial helping behavior is a highly valued social practice across societies, but the willingness to help others varies among persons. In our opinion, that willingness should be associated with the sensitivity to helping outcome at the individual level - that is, increasing as a function of positive outcome sensitivity but decreasing as a function of negative outcome sensitivity. To examine this possibility, we asked participants to make helping decisions in a series of hypothetical scenarios, which provided outcome feedback (positive/negative) of those decisions. Event-related potential (ERP) response to helping outcome was recorded, such that the feedback-related negativity (FRN) and P300 were supposed to reflect the sensitivity to negative outcome and positive outcome, respectively. After the formal task, participants were asked if they would like to donate money to a charity. Consistent with our hypothesis, we found that compared to those who were not willing to donate, the participants who donated money (22 of 41 individuals) showed a smaller FRN but a larger P300. Among these participants, the amount of donation was negatively correlated with FRN response to negative outcome, but positively correlated with P300 response to positive outcome. These findings support the importance of helping outcome sensitivity to prosocial behavior.

The Relation Between Belief in a Just World and Early Processing of Deserved and Undeserved Outcomes: An ERP Study

We used event-related potentials (ERPs) to examine how quickly people in general, and certain people in particular, process deservingness-relevant information. Female university students completed individual difference measures, including individual differences in the belief in a just world (BJW), a belief that people get what they deserve. They then read stories in which an outcome was deserved, undeserved, or neither deserved nor undeserved (i.e., "neutral") while their ERPs were recorded with scalp electrodes. We found no overall differentiation between early ERP responses (< 300 ms post stimulus onset) to deserved, undeserved, and neutral outcomes. However, BJW correlated with the difference between early ERP responses to these forms of information (rs from |.44| to |.61|; ps from .018 to < .001). The early nature of our effects (e.g., 96 ms after stimulus onset) suggests individual differences in socially-relevant information processing that begins before conscious evaluation of the stimuli. Potential underlying processes include automatic attention to schema-relevant information and to unexpected (and therefore salient) information and automatic processing of belief-consistent information. Our research underscores the importance of the concept of deservingness in human information processing as well as the utility of ERP technology and robust statistical analyses in investigations of complex social stimuli.

You are excusable! Neural correlates of economic neediness on empathic concern and fairness perception

There is ample experimental evidence showing that the proposers' social role is related to individuals' fairness perception in the Ultimatum Game (UG). However, various social roles, e.g., degree of economic neediness, have different influences on fairness perception, yet it has not been well studied. In this study, we adapted the UG paradigm and recorded electroencephalography (EEG) to probe the neural signatures of whether and how the degree of neediness influences fairness perception. Behavioral results showed that responders are prone to accept unfair offers from proposers in need more than those who are not in need. At the brain level, MFN (medial frontal negativity) was more negative-going in response to unfair than fair offers for not-in-need proposers. In contrast, we found a reversed MFN difference response to unfair and fair offers for in-need proposers, showing a strongly pure altruistic phenomenon. Moreover, we found smaller P300 amplitude was induced in the proposer-in-need condition, compared with its counterpart, while a negative correlation between empathy rating and P300 amplitude in the proposer-in-need condition regardless of the offers' fairness. The current results indicate that the degree of neediness might reduce fairness perception by promoting the empathic concern toward the in-need proposers rather than decreasing the empathic concern for the not-in-need proposers.

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 (UG) 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.

The choice levels modulate outcome processing during outcome independent of behavior selection: Evidence from event-related potentials

Having a choice is a basic demand to influence human behavior. However, how various choice levels modulate outcome processing when the outcome is independent of the choices remains unclear. In this event-related potential (ERP) study, thirty-seven participants were instructed to perform a one-person choice task in which they were required to choose one card from 1 (no-choice level), 2 (medium-choice level), and 8 cards (high-choice level) to win a reward, with a 50% chance. Behavioral results indicated that pleasure and perceived control rating scores were linearly promoted with increased choice levels. ERP results revealed that having choices (medium- and high-choice level) elicited greater original-RewP and PCA-RewP amplitudes than having no choice (no-choice level), suggesting the amplification of the reward prediction error by quickly detecting whether there is a choice or not. Moreover, ERP results revealed that the original-P300 amplitudes were linearly enhanced with increased choice levels, suggesting the increased attentional allocation based on the motivational and emotional significance, due to advanced processing of the value of choice levels. Therefore, these results suggest that choice levels can modulate outcome processing, even when the outcome is independent of the choices, and provide further evidence to support the intrinsic value of having choices.