Dissociation between medial frontal negativity and cardiac responses in the ultimatum game: Effects of offer size and fairness

A premium for positive social interest and attractive voices in the acceptability of unfair offers? An ERP study

Although the attractiveness of voices plays an important role in social interactions, it is unclear how voice attractiveness and social interest influence social decision-making. Here, we combined the ultimatum game with recording event-related brain potentials (ERPs) and examined the effect of attractive versus unattractive voices of the proposers, expressing positive versus negative social interest ("I like you" vs. "I don't like you"), on the acceptance of the proposal. Overall, fair offers were accepted at significantly higher rates than unfair offers, and high voice attractiveness increased acceptance rates for all proposals. In ERPs in response to the voices, their attractiveness and expressed social interests yielded early additive effects in the N1 component, followed by interactions in the subsequent P2, P3 and N400 components. More importantly, unfair offers elicited a larger Medial Frontal Negativity (MFN) than fair offers but only when the proposer's voice was unattractive or when the voice carried positive social interest. These results suggest that both voice attractiveness and social interest moderate social decision-making and there is a similar "beauty premium" for voices as for faces.

The impact of facial attractiveness and alleged personality traits on fairness decisions in the ultimatum game: Evidence from ERPs

In the mind of the beholder the personality and facial attractiveness of others are interrelated. However, how these specific properties are processed in the neurocognitive system and interact with each other while economic decisions are made is not well understood. Here, we combined the ultimatum game with EEG technology, to investigate how alleged personality traits and the perceived facial attractiveness of proposers of fair and unfair offers influence their acceptance by the responders. As expected, acceptance rate was higher for fair than unfair allocations. Overall, responders were more likely to accept proposals from individuals with higher facial attractiveness and with more positive personality traits. In ERPs, words denoting negative personality traits elicited larger P2 components than positive trait words, and more attractive faces elicited larger LPC amplitudes. Replicating previous findings, FRN amplitudes were larger to unfair than to fair allocations. This effect was diminished if the proposer's faces were attractive or associated with positive personality traits. Hence, facial attractiveness and the valence of personality traits seem to be evaluated independently and at different time points. Subsequent decision making about unfair offers is similarly influenced by high attractiveness and positive personality of the proposer, diminishing the negative response normally elicited by "unfair" proposals, possibly due a "reward" effect. In the ERPs to the proposals the effect of positive personality and attractiveness were seen in the FRN and P300 components but for positive personality traits the effect even preceded the FRN effect. Altogether, the present results indicate that both high facial attractiveness and alleged positive personality mitigate the effects of unfair proposals, with temporally overlapping but independent neurocognitive correlates.

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.

Electrophysiological correlates of third-party punishment: ERP study

Human societies benefit from social norms that increase cooperation and support social order. Hence, the understanding of effective mechanisms enforcing norms is crucial. One of such mechanisms is "third-party punishment" (TPP) - a form of social punishment that could be delivered by a third-party, not directly affected by the actions of the norm violator. Previous electrophysiological studies (ERP) reported that perceived violations of norms evoked the medial frontal negativity in third-parties. The current study further probed the link between the medial frontal negativity (MFN) and actual TPP of norm violation, as it was not shown directly before. Participants played a dictator game as third-parties, being able to select different levels of punishment of an unfair violator's decisions. We replicated previous findings and showed the amplitude of the MFN correlated with the intensity of TPP (Fz, r = -0.516, p = 0.034, FCz, r = -0.509; p = 0.037). Overall, our findings further support the direct link between the MFN and the intensity of TPP.

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.

Electrophysiological Markers of Fairness and Selfishness Revealed by a Combination of Dictator and Ultimatum Games

Individual behavior during financial decision making is motivated by fairness, but an unanswered question from previous studies is whether particular patterns of brain activity correspond to different profiles of fairness. Event Related Potentials (ERPs) were recorded from 39 participants who played the role of allocators in a Dictator Game (DG) and responders in an Ultimatum Game (UG). Two very homogeneous groups were formed by fair and selfish individuals. At fronto-central cortical sites, the latency of ERP early negativity (N1) was 10 ms shorter in selfish participants than in fair participants. In fair DG players, the subsequent positive wave P2 suggested that more cognitive resources were required when they allocated the least gains to the other party. P2 latency and amplitude in the selfish group supported the hypothesis that these participants tended to maximize their profit. During UG, we observed that medial frontal negativity (MFN) occurred earlier and with greater amplitude when selfish participants rejected less favorable endowment shares. In this case, all players received zero payoffs, which showed that MFN in selfish participants was associated with a spiteful punishment. At posterior-parietal sites, we found that the greater the selfishness, the greater the amplitude of the late positive component (LPC). Our results bring new evidence to the existence of specific somatic markers associated with the activation of distinct cerebral circuits by the evaluation of fair and unfair proposals in participants characterized by different expressions of perceived fairness, thus suggesting that a particular brain dynamics could be associated with moral decisions.

Cardiac deceleration following positive and negative feedback is influenced by competence-based social status

Previous studies indicate that neurophysiological signatures of feedback processing might be enhanced when participants are assigned a low-status position. Error commission and negative feedback can evoke responses in the peripheral (autonomic) nervous system including heart rate deceleration. We conducted an exploratory study to investigate whether such activity can be modulated by the participant's social status in a competence-based hierarchy. Participants were engaged in a cooperative time estimation task with two same-gender confederates. On each trial, they were provided with positive or negative feedback depending on their time estimation performance. Their social status varied during the task, so that they were either at the top (high-status) or at the bottom (low-status) of the hierarchy in different blocks. Results showed that cardiac deceleration was significantly modulated by feedback valence in the high-status but not in the low-status condition. We interpret this result as an increased activation of the performance monitoring system elicited by the desire to maintain a high-status position in an unstable hierarchy. In this vein, negative feedback might be processed as an aversive stimulus that signals a threat to the acquired status.

The Role of Leadership Level in College Students' Decision-Making: Evidence From Event-Related Potential Analysis

Although risk decision-making plays an important role in leadership practice, the distinction in behavior between humans with differing levels of leadership, as well as the underlying neurocognitive mechanisms involved, remain unclear. In this study, the Ultimatum Game (UG) was utilized in concert with electroencephalograms (EEG) to investigate the temporal course of cognitive and emotional processes involved in economic decision-making between high and low leadership level college students. Behavioral results from this study found that the acceptance rates in an economic transaction, when the partner was a computer under unfair/sub unfair condition, were significantly higher than in transactions with real human partners for the low leadership group, while there was no significant difference in acceptance rates for the high leadership group. Results from Event-Related Potentials (ERP) analysis further indicated that there was a larger P3 amplitude in the low leadership group than in the high leadership group. We concluded that the difference between high and low leadership groups was at least partly due to their different emotional management abilities.

Ranking status differentially affects rejection sensitivity in adolescence: An event-related potential study

Adolescents are sensitive to peer rejection but this may be dependent on their status. This study examined the role of ranking status on rejection sensitivity in adolescence using an experimental bargaining design. To manipulate ranking status, participants between ages 9-22-years (final sample n = 102) performed a reaction time task with two peers to induce high and low status. Next, participants played an iterative Ultimatum Game as high or low status proposer with an opposite status responder. Rejection of fair offers was associated with larger Medial Frontal Negativity (MFN) compared to acceptance of fair offers. An interaction between age and status group revealed that after rejection of fair offers, mid-adolescents showed a larger MFN when having a low status and smaller MFN when having a high status, relative to children and adults. These findings suggest that the MFN reacts as a neural alarm system to social prediction errors, signaling a need for vigilance to deviations from the norm, which is influenced by ranking status especially during mid-adolescence.

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.

The semiotics of the message and the messenger: How nonverbal communication affects fairness perception

Nonverbal communication determines much of how we perceive explicit, verbal messages. Facial expressions and social touch, for example, influence affinity and conformity. To understand the interaction between nonverbal and verbal information, we studied how the psychophysiological time-course of semiotics—the decoding of the meaning of a message—is altered by interpersonal touch and facial expressions. A virtual-reality-based economic decision-making game, ultimatum, was used to investigate how participants perceived, and responded to, financial offers of variable levels of fairness. In line with previous studies, unfair offers evoked medial frontal negativity (MFN) within the N2 time window, which has been interpreted as reflecting an emotional reaction to violated social norms. Contrary to this emotional interpretation of the MFN, however, nonverbal signals did not modulate the MFN component, only affecting fairness perception during the P3 component. This suggests that the nonverbal context affects the late, but not the early, stage of fairness perception. We discuss the implications of the semiotics of the message and the messenger as a process by which parallel information sources of “who says what” are integrated in reverse order: of the message, then the messenger.

I'll make you an offer you can refuse: How socially sensitive is the MFN?

Medial frontal negativity (MFN) is an event-related potential thought to originate in the anterior cingulate cortex. It is evoked by outcomes being worse than expected, such as when presented with unfair economic proposals during the Ultimatum Game (UG). This could mean the MFN indexes a social-emotional response, as commonly suggested in accounts that relate it to a violation of a social norm of fairness. To examine the link between MFN and norm violation, we designed an EEG experiment with participants acting as representatives in an UG. Participants responded either as themselves, or as representatives of two charities. Of these, a norm-compatible charity conformed to the participant's values, while the norm-incompatible charity contrasted to them. The behavioral results showed that norm-incompatible representation reversed behavior, with almost all fair offers being declined. The MFN, however, was unaffected by the norm representation, with unfair offers consistently evoking MFNs across conditions. We furthermore replicated the curious finding that unexpectedly generous offers evoke as much MFN as unfair offers. Thus, the MFN is not nearly as sensitive to higher-order social-emotional processes as commonly assumed. Instead, the perceived inequality that drives the MFN likely reflects a rational, probabilistic process.

Behavioral and electrophysiological responses to fairness norm violations in antisocial offenders

Antisocial personality disorder is characterized by a stable, lifelong pattern of disregard for and violation of others' rights. Disruptions in the representation of fairness norms may represent a key mechanism in the development and maintenance of this disorder. Here, we investigated fairness norm considerations and reactions to their violations. To examine electrophysiological correlates, we assessed the medial frontal negativity (MFN), an event-related potential previously linked to violations of social expectancy and norms. Incarcerated antisocial violent offenders (AVOs, n = 25) and healthy controls (CTLs, n = 24) acted as proposers in the dictator game (DG) and ultimatum game (UG) and received fair vs. unfair UG offers from either another human (social context) or a computer (non-social context). Results showed that AVOs made lower offers in the DG but not the UG, indicating more rational and strategic behavior. Most importantly, when acting as recipients in the UG, acceptance rates were modulated by social context in CTLs, while AVOs generally accepted more offers. Correspondingly, ERP data indicated pronounced MFN amplitudes following human offers in CTLs, whereas MFN amplitudes in AVOs were generally reduced. The current data suggest intact fairness norm representations but altered reactions to their violation in antisocial personality disorder.

The neural correlate of mid-value offers in ultimatum game

In the ultimatum game (UG), mid-value offers are unfair but not so unreasonable as to be rejected immediately. As a consequence, they are difficult for responders to evaluate because of the conflict that arises between two key processes, namely inequity aversion and self-interests. Since there is no clear consensus in the literature on event-related potential (ERP) as to how mid-value offers are processed, we designed an experiment to explore how the ability to reject offers influences key ERP signatures. By manipulating the right to reject offers based on game type (ultimatum game, UG or dictator game, DG), our study explored how ERPs were influenced by three types of offers available to participants (fair, unfair and mid-value). We recorded the electroencephalogram results of 28 participants while they responded to the three kinds of offers in the UG and the DG. We observed that mid-value offers in the UG elicited more negative feedback-related negativity and N400 than did the unfair offers. However, these ERP patterns were specific to the UG. Furthermore, we interpreted these results as further electrophysiological evidence of the interaction between the two processing systems during the UG.

Money for me and money for friend: An ERP study of social reward processing in adolescents and adults

Peer relations during adolescence contribute significantly to the development of socio-cognitive skills and pro-sociality. The current study probed the characteristics of adolescent socio-cognitive processing through a card game where they earn money for self and friend. We investigated the choice preference and temporal dynamics of information processing by measuring ERP responses to wins or losses (valence) directed toward self and friend (recipient). Choice data showed that despite adults and adolescents earning equivalent amounts across recipients combined, adults won significantly more for self than a friend; no such difference was found in adolescents. The ERPs in response to choice outcomes showed that the valence information was processed earlier (at P2) in adults, while it was processed later (at P3) in adolescents. Furthermore, a strong effect of recipient was present in adults later in the time course (at P3), while such an effect was weak in adolescents; if any, adolescents showed sensitivity to recipient information earlier at P2. These ERP data suggest a relatively equal allocation of the P3-mediated attentional process to both self and friend's outcomes in adolescents, which parallels the choice behavior. Collectively our results characterize adolescent pro-sociality toward friends, reflecting the importance of peer relationship during this unique developmental period.

Social hierarchies in third-party punishment: A behavioral and ERP study

Third-party punishment refers to the punishment imposed by a party whose benefit is not directly affected by any norm violations. The present study using a modified Dictator Game explored how social statuses of the involved parties modulate punishment decisions of a third-party. Systematic manipulation of the dictators' and recipients' status revealed that: higher recipient status correlated with more severe punishment, but no effect of the dictator's. We further focused on the neural underlying of this effect using ERPs. An interaction of recipient's status × fairness was observed on MFN such that only for a high-status recipient, larger amplitude was triggered by unfair offers comparing to fair offers. On LPC, the largest amplitude was observed when the offer was fair and the recipient had medium-status. These findings suggested: participants consider unfair offers proposed to high-status recipients as more norm-violating and they may evaluate the offers from the perspective of the recipient.

Hello handsome! Male's facial attractiveness gives rise to female's fairness bias in Ultimatum Game scenarios-An ERP study

The current study delineated how male proposers’ facial attractiveness affect female responders’ fairness considerations and their subsequent decision outcome during the Ultimatum Game (UG). Event Related Potentials (ERPs) were recorded from 17 female subjects, who played the role as responders and had to decide whether to accept offers from either attractive or unattractive male proposers. Behavioral data (Acceptance Ratio and Response time) revealed that, more offers were accepted from attractive-face conditions; subjects typically responded quicker to unfair offers from unattractive proposers as compared with slower to unfair offers from attractive proposers. The ERP data demonstrated similar N2 amplitudes elicited by both attractive and unattractive faces, and a larger early frontal LPP elicited by the attractive faces compared with unattractive ones, but no significant differences of both late posterior LPP and typical parietal LPP amplitudes were observed between these two face conditions, which was different from our previous study with similar paradigm but male participants. The results suggest that, in comparison to males, females might not experience the potential attention bias towards unattractive opposite-sex faces and are less likely to possess an enhanced processing and evaluation of those faces. This phenomenon might be explained by endogenous gender differences in mate preference. The feedback-related negativity (FRN) and P300 responses during an offer presentation were further measured in both attractive-face and unattractive-face conditions and the results demonstrated that the amplitudes elicited by fair and unfair offers were not statistically different in the former condition, but were different in the latter condition. More specifically, unfair offers generated larger FRN and smaller P300 than fair ones in the unattractive-face condition. Findings suggest that, although females tend to possess less salient evaluation of male’s facial attractiveness, the attractiveness of male proposers would still attenuate female responders’ fairness consideration during the UG.

Be Strong Enough to Say No: Self-Affirmation Increases Rejection to Unfair Offers

We propose that self-affirmation may endow people more psychological resources to buffer against the negative influence of rejecting unfair offers in the classic ultimatum game (UG) and further lead to a stronger tendency to reject those offers. We tested this possibility by conducting an event-related potential (ERP) study about the UG, with the ERP component P3 as an indirect indicator of psychological resources. Participants were randomly assigned to the affirmation or control condition and then completed the UG through electrophysiological recording. As expected, the behavioral data indicated that compared with unaffirmed ones, affirmed participants were more likely to reject unfair UG offers; the electrophysiological data indicated that compared to the unaffirmed, affirmed participants showed a greater P3 in response to the presentation of an offer. These findings suggest that psychological resources may play a role in rejecting others beyond the fairness concern, and additionally shed light on the neural mechanisms underlying self-affirmation.

Behavioral and neuronal determinants of negative reciprocity in the ultimatum game

The rejection of unfair offers in the ultimatum game (UG) indicates negative reciprocity. The model of strong reciprocity claims that negative reciprocity reflects prosociality because the rejecting individual is sacrificing resources in order to punish unfair behavior. However, a recent study found that the rejection rate of unfair offers is linked to assertiveness (status defense model). To pursue the question what drives negative reciprocity, the present study investigated individual differences in the rejection of unfair offers along with their behavioral and neuronal determinants. We measured fairness preferences and event-related potentials (ERP) in 200 healthy participants playing a computerized version of the UG with pictures of unfair and fair proposers. Structural equation modeling (SEM) on the behavioral data corroborated both the strong reciprocity and the status defense models of human cooperation: Not only more prosocial but also more assertive individuals were more likely to show negative reciprocity by rejecting unfair offers. Experimental ERP results confirmed the feedback negativity (FN) as a neural signature of fairness processing. Multilevel SEM of brain-behavior relationships revealed that negative reciprocity was significantly associated with individual differences in FN amplitudes in response to proposers. Our results confirm stable individual differences in fairness processing at the behavioral and neuronal level.

Medial frontal negativity reflects advantageous inequality aversion of proposers in the ultimatum game: An ERP study

Inequality aversion is a typical form of fairness preferences, which can explain the behaviors in many social exchange situations such as the ultimatum game (UG). There are two kinds of inequality aversion-disadvantageous inequality aversion of responders and advantageous inequality aversion of proposers in the ultimatum game. Although neuroscience research has reported neural correlates of disadvantageous inequality aversion, there are still debates about advantageous inequality aversion of proposers. In this paper, we developed a variant of ultimatum game in which participants played the UG as proposers. On each trial, first, the offer was randomly presented, then, participants as proposers decided whether to choose this offer; next, responders decided whether to accept or not. Offers that responders got 1-20% of the pie are defined as advantageous unfair offers of proposers, whereas offers that responders got 31-50% are defined as fair offers. Event-related brain potentials recorded from the participants showed that more negative-going medial frontal negativity (MFN) was elicited by advantageous unfair offers compared to fair offers in the early time window (250-350ms), which suggested that proposers were averse to advantageous inequality.

Rejection in Bargaining Situations: An Event-Related Potential Study in Adolescents and Adults

The neural correlates of rejection in bargaining situations when proposing a fair or unfair offer are not yet well understood. We measured neural responses to rejection and acceptance of monetary offers with event-related potentials (ERPs) in mid-adolescents (14-17 years) and early adults (19-24 years). Participants played multiple rounds of the Ultimatum Game as proposers, dividing coins between themselves and a second player (responder) by making a choice between an unfair distribution (7 coins for proposer and 3 for responder; 7/3) and one of two alternatives: a fair distribution (5/5) or a hyperfair distribution (3/7). Participants mostly made fair offers (5/5) when the alternative was unfair (7/3), but made mostly unfair offers (7/3) when the alternative was hyperfair (3/7). When participants' fair offers (5/5; alternative was 7/3) were rejected this was associated with a larger Medial Frontal Negativity (MFN) compared to acceptance of fair offers and rejection of unfair offers (7/3; alternative was 3/7). Also, the MFN was smaller after acceptance of unfair offers (7/3) compared to rejection. These neural responses did not differ between adults and mid-adolescents, suggesting that the MFN reacts as a neural alarm system to social prediction errors which is already prevalent during adolescence.

The effect of altruistic tendency on fairness in third-party punishment

Third-party punishment, as an altruistic behavior, was found to relate to inequity aversion in previous research. Previous researchers have found that altruistic tendencies, as an individual difference, can affect resource division. Here, using the event-related potential (ERP) technique and a third-party punishment of dictator game paradigm, we explored third-party punishments in high and low altruists and recorded their EEG data. Behavioral results showed high altruists (vs. low altruists) were more likely to punish the dictators in unfair offers. ERP results revealed that patterns of medial frontal negativity (MFN) were modulated by unfairness. For high altruists, high unfair offers (90:10) elicited a larger MFN than medium unfair offers (70:30) and fair offers (50:50). By contrast, for low altruists, fair offers elicited larger MFN while high unfair offers caused the minimal MFN. It is suggested that the altruistic tendency effect influences fairness consideration in the early stage of evaluation. Moreover, the results provide further neuroscience evidence for inequity aversion.

The undermining effect of facial attractiveness on brain responses to fairness in the Ultimatum Game: an ERP study

To investigate the time course of the neural processing of facial attractiveness and its influence on fairness consideration during social interactions, event-related potentials (ERP) were recorded from 21 male subjects performing a two-person Ultimatum Game (UG). During this bargaining game, the male subjects played responders who decided whether to accept offers from female proposers, whose facial images (grouped as "attractive" and "unattractive") were presented prior to the offer presentation. The behavioral data demonstrated that the acceptance ratio increased with the fairness level of the offers and, more importantly, the subjects were more likely to accept unfair offers when presented with the attractive-face condition compared with the unattractive-face condition. The reaction times (RTs) for five offers (1:9, 2:8, 3:7, 4:6, and 5:5) in the unattractive-face condition were not significantly different. In contrast, the subjects reacted slower to the attractive proposers' unfair offers and quicker to fair offers. The ERP analysis of the face presentation demonstrated a decreased early negativity (N2) and enhanced late positive potentials (LPPs) elicited by the attractive faces compared with the unattractive faces. In addition, the feedback-related negativity (FRN) in response to an offer presentation was not significantly different for the unfair (1:9 and 2:8) and fair (4:6 and 5:5) offers in the attractive-face condition. However, the unfair offers generated larger FRNs compared with the fair offers in the unattractive-face condition (consistent with prior studies). A similar effect was identified for P300. The present study demonstrated an undermining effect of proposer facial attractiveness on responder consideration of offer fairness during the UG.

Counterfactual comparison modulates fairness consideration in the mini-ultimatum game: an event-related potentials study

Existing literature on the mini-ultimatum game indicates that counterfactual comparison between chosen and unchosen alternatives is of great importance for individual's fairness consideration. However, it is still unclear how counterfactual comparison influences the electrophysiological responses to unfair chosen offers. In conjunction with event-related potentials' (ERPs) technique, the current study aimed to explore the issue by employing a modified version of the mini-ultimatum game where a fixed set of two alternatives (unfair offer vs. fair alternative, unfair vs. hyperfair alternative, unfair offer vs. hyperunfair alternative) was presented before the chosen offer. The behavioral results showed that participants were more likely to accept unfair chosen offers when the unchosen alternative was hyperunfair than when the unchosen alternative was fair or hyperfair. The ERPs results showed that the feedback-related negativity (FRN) elicited by unfair chosen offers was insensitive to the type of unchosen alternative when correcting for possible overlap with other components. In contrast, unfair chosen offers elicited larger P300 amplitudes when the unchosen alternative was hyperunfair than when the unchosen alternative was fair or hyperfair. These findings suggest that counterfactual comparison may take effect at later stages of fairness consideration as reflected by the P300.

The heart-break of social rejection versus the brain wave of social acceptance

The effect of social rejection on cardiac and brain responses was examined in a study in which participants had to decide on the basis of pictures of virtual peers whether these peers would like them or not. Physiological and behavioral responses to expected and unexpected acceptance and rejection were compared. It was found that participants expected that about 50% of the virtual judges gave them a positive judgment. Cardiac deceleration was strongest for unexpected social rejection. In contrast, the brain response was strongest to expected acceptance and was characterized by a positive deflection peaking around 325 ms following stimulus onset and the observed difference was maximal at fronto-central positions. The cardiac and electro-cortical responses were not related. It is hypothesized that these differential response patterns might be related to earlier described differential involvement of the dorsal and ventral portion of the anterior cingulate cortex.

The temporal course of the influence of anxiety on fairness considerations

This study investigated the potential causes of anxious people's social avoidance. The classic ultimatum game was utilized in concert with electroencephalogram recording. Participants were divided into two groups according to levels of trait anxiety as identified by a self-report scale. The behavioral results indicate that high-anxious participants were more prone to reject human-proposed than computer-proposed unequal offers compared to their low-anxious counterparts. The event-related potential results indicate that the high-anxious group showed a larger feedback-related negativity when receiving unequal monetary offers than equal ones, and a larger P3 when receiving human-proposed offers than computer-proposed ones, but these effects were absent in the low-anxious group. We suggest anxious people's social avoidance results from hypersensitivity to unequal distributions during interpersonal interactions.

Social information and personal interests modulate neural activity during economic decision-making

In the present study we employed electrophysiological recordings to investigate the levels of processing at which positive and negative descriptions of other people bias social decision-making in a game in which participants accepted or rejected economic offers. Besides social information, we manipulated the fairness of the assets distribution, whether offers were advantageous or not for the participant and the uncertainty of the game context. Results show that a negative description of the interaction partner enhanced the medial frontal negativity (MFN) in an additive manner with fairness evaluations. The description of the partner interacted with personal benefit considerations, showing that this positive or negative information only biased the evaluation of offers when they did not favor the participant. P300 amplitudes were enhanced by advantageous offers, suggesting their heightened motivational significance at later stages of processing. Throughout all stages, neural activity was enhanced with certainty about the personal assignments of the split. These results provide new evidence on the importance of interpersonal information and considerations of self-interests relative to others in decision-making situations.

Core disgust and moral disgust are related to distinct spatiotemporal patterns of neural processing: an event-related potential study

Core disgust is thought to rely more on sensory and perceptual processes, whereas moral disgust is thought to rely more on social evaluation processes. However, little is known about the neurocognitive mechanisms underlying these two types of disgust. We recorded event-related potentials (ERPs) from participants while they performed a lexical decision task in which core- and moral-disgust words were intermixed with neutral words and pseudowords. Lexical judgment was faster for coredisgust words and slower for moral-disgust words, relative to the neutral words. Core-disgust words, relative to neutral words, elicited a larger early posterior negative (EPN), a larger N320, a smaller N400, and a larger late positive component (LPC), whereas moral disgust words elicited a smaller N320 and a larger N400 than neutral words. These results suggest that the N320 and N400 components are particularly sensitive to the neurocognitive processes that overlap in processing both core and moral disgust, whereas the EPN and LPC may reflect process that are particularly sensitive to core disgust.

Distinct neural activation patterns underlie economic decisions in high and low psychopathy scorers

Psychopathic traits affect social functioning and the ability to make adaptive decisions in social interactions. This study investigated how psychopathy affects the neural mechanisms that are recruited to make decisions in the ultimatum game. Thirty-five adult participants recruited from the community underwent functional magnetic resonance imaging scanning while they performed the ultimatum game under high and low cognitive load. Across load conditions, high psychopathy scorers rejected unfair offers in the same proportion as low scorers, but perceived them as less unfair. Among low scorers, the perceived fairness of offers predicted acceptance rates, whereas in high scorers no association was found. Imaging results revealed that responses in each group were associated with distinct patterns of brain activation, indicating divergent decision mechanisms. Acceptance of unfair offers was associated with dorsolateral prefrontal cortex activity in low scorers and ventromedial prefrontal cortex activity in high scorers. Overall, our findings point to distinct motivations for rejecting unfair offers in individuals who vary in psychopathic traits, with rejections in high psychopathy scorers being probably induced by frustration. Implications of these results for models of ventromedial prefrontal cortex dysfunction in psychopathy are discussed.

A neural signature of the creation of social evaluation

Previous research has shown that receiving an unfair monetary offer in economic bargaining elicits also-called feedback negativity (FN). This scalp-recorded brain potential probably reflects a bad-vs-good evaluation in the medial frontal cortex and has been linked to fundamental processes of reinforcement learning. In the present study, we investigated whether the evaluative mechanism indexed by the FN is also involved in learning who is an unfair vs fair bargaining partner. An electroencephalogram was recorded while participants completed a computerized version of the Ultimatum Game, repeatedly receiving fair or unfair monetary offers from alleged other participants. Some of these proposers were either always fair or always unfair in their offers. In each trial, participants first saw a portrait picture of the respective proposer before the monetary offer was presented. Therefore, the faces could be used as predictive cues for the fairness of the pending offers. We found that not only unfair offers themselves induced a FN, but also (over the task) faces of unfair proposers. Thus, when interaction partners repeatedly behave in an unfair way, their faces acquire a negative valence, which manifests in a basal neural mechanism of bad-vs-good evaluation.

Performance monitoring and the medial prefrontal cortex: a review of individual differences and context effects as a window on self-regulation

The medial prefrontal cortex (MPFC) is central to self-regulation and has been implicated in generating a cluster of event-related potential components, collectively referred to as medial frontal negativities (MFNs). These MFNs are elicited while individuals monitor behavioral and environmental consequences, and include the error-related negativity, Nogo N2, and the feedback-related negativity. A growing cognitive and affective neuroscience literature indicates that the activation of the anterior cingulate cortex (ACC) and surrounding medial prefrontal regions during performance monitoring is not only influenced by task context, but that these patterns of activity also vary as a function of individual differences (e.g., personality, temperament, clinical and non-clinical symptomatology, socio-political orientation, and genetic polymorphisms), as well as interactions between individual differences and task context. In this review we survey the neuroscience literature on the relations between performance monitoring, personality, task context, and brain functioning with a focus on the MPFC. We relate these issues to the role of affect in the paradigms used to elicit performance-monitoring neural responses and highlight some of the theoretical and clinical implications of this research. We conclude with a discussion of the complexity of these issues and how some of the basic assumptions required for their interpretation may be clarified with future research.

Social Comparison Affects Brain Responses to Fairness in Asset Division: An ERP Study with the Ultimatum Game

Previous studies have shown that social comparison influences individual’s fairness consideration and other-regarding behavior. However, it is not clear how social comparison affects the brain activity in evaluating fairness during asset distribution. In this study, participants, acting as recipients in the ultimatum game, were informed not only of offers to themselves but also of the average amount of offers in other allocator–recipient dyads. Behavioral results showed that the participants were more likely to reject division schemes when they were offered less than the other recipients, especially when the offers were highly unequal. Event-related brain potentials recorded from the participants showed that highly unequal offers elicited more negative-going medial frontal negativity than moderately unequal offers in an early time window (270–360 ms) and this effect was not significantly modulated by social comparison. In a later time window (450–650 ms), however, the late positive potential (LPP) was more positive for moderately unequal offers than for highly unequal offers when the other recipients were offered less than the participants, whereas this distinction disappeared when the other recipients were offered the same as or more than the participants. These findings suggest that the brain activity in evaluating fairness in asset division entails both an earlier (semi-) automatic process in which the brain responds to fairness at an abstract level and a later appraisal process in which factors related to social comparison and fairness norms come into play.