Processing of fair and unfair offers in the ultimatum game under social observation

Deconstructing Temporal Stages of Prosocial and Antisocial Risky Decision-making in Adolescence

Risk-taking is a prominent aspect of adolescent behavior. A recent neurodevelopmental model suggests that this trait could influence prosocial and antisocial decision-making, proposing a new category known as prosocial and antisocial risk-taking. The primary objective of this study was to examine the electrophysiological underpinnings of prosocial and antisocial risk-taking in adolescence, a developmental period characterized by elevated risky, prosocial, and antisocial decisions. To this end, 32 adolescents aged 13-19 years completed a modified dictator game to choose between three options, representing prosocial and antisocial risk-taking constructs and a risk-free fair one. At the behavioral level, adolescents favored antisocial risky decisions over prosocial risky ones. ERP results at the electrophysiological level in the response selection stage demonstrated that decision preceding negativity was more negative-going before making prosocial risky decisions than other decisions. During the feedback evaluation stage, feedback-related negativity was the least negative after selecting the antisocial risky option and receiving successful feedback. However, choosing the fair option and receiving neutral feedback resulted in the most negative feedback-related negativity. Moreover, P300 showed the most positive mean amplitude following the selection of the antisocial risky option and facing successful feedback, with the lowest positive amplitude observed after choosing the fair option and encountering neutral feedback. These results underscore the distinct electrophysiological underpinnings associated with prosocial and antisocial decisions involving risks.

Electrophysiological correlates of why humans deviate from rational decision-making: A registered replication study

In contrast to rational choice theory predicting humans to optimize expected utilities of choices, humans deviate from rational behavior in decision-making paradigms. Hewig et al. (2011) explored affective correlates of decision-making in the ultimatum game (UG) and the dictator game (DG). They found that feedback-related negativity (FRN), subjective valence ratings, and autonomic nervous system activity predicted rejection of monetary offers. This registered replication aimed to validate and extend these findings. Although behavioral patterns and results of subjective ratings closely matched the original study, not all psychophysiological effects were successfully replicated. Firstly, we could not replicate the reported effects of autonomic nervous system activity. Secondly, a quadratic instead of the originally proposed linear relation between the offer and the FRN emerged, possibly driven by the offer evaluation in economic games and the rewarding anticipation of successful punishment for low offers. Thirdly, P3 amplitudes mirrored the quadratic offer response pattern, generally peaking for the lowest offer. In contrast to the original study, P3 responses were larger in the UG compared with the DG. Finally, our findings indicate that participant-related higher midfrontal theta activation predicted lower acceptance behavior in the UG, with a systematic dampening effect for fairer offers. This highlights cognitive control as a crucial mechanism in economic decision-making to overcome behavioral defaults. Overall, our results conceptually support the original conclusion that decision-making in economic games is non-rational and dependent on the objective situation as well as emotional and neural markers, though not precisely as suggested by Hewig et al. (2011).

Rejecting unfairness enhances the implicit sense of agency in the human brain

Sense of agency (SoA) describes the feeling of control over one's actions and their consequences. One proposed index of implicit SoA is temporal compression, which refers to the phenomenon that voluntary actions and their outcomes are perceived as closer in time than they actually are. The present study measured temporal compression in the social norm violation situation. In two experiments participants joined in an Ultimatum game (UG), in which they were presented with offers that varied in fairness and they could choose to accept or reject the offers by pressing buttons. A neutral sound would occur after their choices in the UG and the participants had to estimate the time interval between their button pressing and the occurrence of the sound, and EEG signals were recorded during the task. Experiment 1 demonstrated that rejecting unfair offers decreased the perceived interval between action and outcome compared to accepting fair offers, suggesting a higher level of SoA after rejecting unfair offers. Experiment 2 replicated these results and further revealed an attenuated N1 in response to the sound following rejections of unfairness. Taken together, these results highlight the importance of social norms in affecting people's behaviors and agency experiences.

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 consequences of AI training on human decision-making

AI is now an integral part of everyday decision-making, assisting us in both routine and high-stakes choices. These AI models often learn from human behavior, assuming this training data is unbiased. However, we report five studies that show that people change their behavior to instill desired routines into AI, indicating this assumption is invalid. To show this behavioral shift, we recruited participants to play the ultimatum game, where they were asked to decide whether to accept proposals of monetary splits made by either other human participants or AI. Some participants were informed their choices would be used to train an AI proposer, while others did not receive this information. Across five experiments, we found that people modified their behavior to train AI to make fair proposals, regardless of whether they could directly benefit from the AI training. After completing this task once, participants were invited to complete this task again but were told their responses would not be used for AI training. People who had previously trained AI persisted with this behavioral shift, indicating that the new behavioral routine had become habitual. This work demonstrates that using human behavior as training data has more consequences than previously thought since it can engender AI to perpetuate human biases and cause people to form habits that deviate from how they would normally act. Therefore, this work underscores a problem for AI algorithms that aim to learn unbiased representations of human preferences.

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.

How and when social evaluative feedback is processed in the brain: A systematic review on ERP studies

Social evaluative feedback informs the receiver of the other's views, which may contain judgments of personality-related traits and/or the level of likability. Such kinds of social evaluative feedback are of particular importance to humans. Event-related potentials (ERPs) can directly measure where in the processing stream feedback valence, expectancy, or contextual relevance modulate information processing. This review provides an overview and systematization of studies and early, mid-latency, and late ERP effects. Early effects were inconsistently reported for all factors. Feedback valence effects are more consistently reported for specific mid-latency ERPs (Reward Positivity, RewP, and Early Posterior Negativity, EPN) and late positivities (P3 and Late Positive Potential, LPP). Unexpected feedback consistently increased the Feedback Related Negativity (FRN) and, less consistently, decreased P3 amplitudes. Contextual relevance of the sender (e.g., human vs computer sender) or self-relatedness increased mid-latency to late ERPs. Interactions between valence and other factors were less often found, arising during mid-latency stages, where most consistent interactions showed larger EPN and P3 amplitude differences for valent feedback in a more relevant context. The ERP findings highlight that social evaluative feedback is consistently differentiated during mid-latency processing stages. The review discusses the relevance of findings, possible shortcomings of different experimental designs, and open questions. Furthermore, we suggest concrete venues for future research.

Resting-state network predicts the decision-making behaviors of the proposer during the ultimatum game

Objective. The decision-making behavior of the proposer is a key factor in achieving effective and equitable maintenance of social resources, particularly in economic interactions, and thus understanding the neurocognitive basis of the proposer's decision-making is a crucial issue. Yet the neural substrate of the proposer's decision behavior, especially from the resting-state network perspective, remains unclear.Approach. In this study, we investigated the relationship between the resting-state network and decision proposals and further established a multivariable model to predict the proposers' unfair offer rates in the ultimatum game.Main results.The results indicated the unfair offer rates of proposers are significantly related to the resting-state frontal-occipital and frontal-parietal connectivity in the delta band, as well as the network properties. And compared to the conservative decision group (low unfair offer rate), the risk decision group (high unfair offer rate) exhibited stronger resting-state long-range linkages. Finally, the established multivariable model did accurately predict the unfair offer rates of the proposers, along with a correlation coefficient of 0.466 between the actual and predicted behaviors.Significance. Together, these findings demonstrated that related resting-state frontal-occipital and frontal-parietal connectivity may serve as a dispositional indicator of the risky behaviors for the proposers and subsequently predict a highly complex decision-making behavior, which contributed to the development of artificial intelligence decision-making system with biological characteristics as well.

Event-related potentials during the ultimatum game in people with symptoms of depression and/or social anxiety

Depression and social anxiety are common disorders that have a profound impact on social functioning. The need for studying the neural substrates of social interactions in mental disorders using interactive tasks has been emphasized. The field of neuroeconomics, which combines neuroscience techniques and behavioral economics multiplayer tasks such as the Ultimatum Game (UG), can contribute in this direction. We assessed emotions, behavior, and Event-Related Potentials in participants with depression and/or social anxiety symptoms (MD/SA, n = 63, 57 females) and healthy controls (n = 72, 67 females), while they played the UG. In this task, participants received fair, mid-value, and unfair offers from other players. Mixed linear models were implemented to assess trial level changes in neural activity. The MD/SA group reported higher levels of sadness in response to mid-value and unfair offers compared to controls. In controls, the Medial Frontal Negativity associated with fair offers increased over time, while this dynamic was not observed in the MD/SA group. The MD/SA group showed a decreased P3/LPP in all offers, compared to controls. These results indicate an enhanced negative emotional response to unfairness in the MD/SA group. Neural results reveal a blunted response over time to positive social stimuli in the MD/SA group. Moreover, between-group differences in P3/LPP may relate to a reduced saliency of offers and/or to a reduced availability of resources for processing incoming stimuli in the MD/SA group. Findings may shed light into the neural substrates of social difficulties in these disorders.

Another in need enhances prosociality and modulates frontal theta oscillations in young adults

Introduction

Decision-making is a process that can be strongly affected by social factors. Evidence has shown how people deviate from traditional rational-choice predictions under different levels of social interactions. The emergence of prosocial decision-making, defined as any action that is addressed to benefit another individual even at the expense of personal benefits, has been reported as an example of such social influence. Furthermore, brain evidence has shown the involvement of structures such as the prefrontal cortex, anterior insula, and midcingulate cortex during decision settings in which a decision maker interacts with others under physical pain or distress or while being observed by others.

Methods

Using a slightly modified version of the dictator game and EEG recordings, we tested the hypothesis that the inclusion of another person into the decision setting increases prosocial decisions in young adults and that this increase is higher when the other person is associated with others in need. At the brain level, we hypothesized that the increase in prosocial decisions correlates with frontal theta activity.

Results and Discussion

The results showed that including another person in the decision, setting increased prosocial behavior only when this presence was associated with someone in need. This effect was associated with an increase in frontocentral theta-oscillatory activity. These results suggest that the presence of someone in need enhances empathy concerns and norm compliance, raising the participants' prosocial decision-making.

Intention affects fairness processing: Evidence from behavior and representational similarity analysis of event-related potential signals

In an ultimatum game, the responder must decide between pursuing self-interest and insisting on fairness, and these choices are affected by the intentions of the proposer. However, the time course of this social decision-making process is unclear. Representational similarity analysis (RSA) is a useful technique for linking brain activity with rich behavioral data sets. In this study, electroencephalography (EEG) was used to measure the time course of neural responses to proposed allocation schemes with different intentions. Twenty-eight participants played an ultimatum game as responders. They had to choose between accepting and rejecting the fair or unfair money allocation schemes of proposers. The schemes were offered based on the proposer's selfish intention (monetary gain), altruistic intention (donation to charity), or ambiguous intention (unknown to the responder). We used a spatiotemporal RSA and inter-subject RSA (IS-RSA) to explore the connections between event-related potentials (ERPs) after offer presentation and intention presentation with four types of behavioral data (acceptance, response time, fairness ratings, and pleasantness ratings). The spatiotemporal RSA results revealed that only response time variation was linked with the difference in ERPs at 432-592 ms after offer presentation on the posterior parietal and prefrontal regions. Meanwhile, the IS-RSA results found a significant association between inter-individual differences in response time and differences in ERP activity at 596-812 ms after the presentation of ambiguous intention, particularly in the prefrontal region. This study expands the intention-based reciprocal model to the third-party context and demonstrates that brain activity can represent response time differences in social decision-making.

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.

Permitting immoral behaviour: A generalized compensation belief hypothesis

When are we more likely to permit immoral behaviours? The current research examined a generalized compensation belief hypothesis that individuals, as observers, would morally tolerate and accept someone paying forward unfair treatment to an innocent person as a means to compensate for the perpetrator's previously experienced mistreatment. Across five experiments (N = 1107) based on economic games (Studies 1-4) and diverse real-life scenarios (Study 5), we showed that participants, as observing third parties, were more likely to morally permit and engage in the same negative act once they knew about previous maltreatment of the perpetrator. This belief occurred even when the content of received and paid-forward maltreatment was non-identical (Study 2), when the negative treatment was received from a non-human target (Study 3) and when the maltreatment was intangible (e.g. material loss) or relational (e.g. social exclusion; Study 5). Perceived required compensation mediated the effect of previous maltreatment on moral permission (Studies 4 and 5). The results consistently suggest that people's moral permission of immoral behaviours is influenced by perpetrator's previous mistreatment, contributing to a better understanding of the nature and nuances of our sense of fairness and contextualized moral judgement.

Neural responses to social decision-making in suicide attempters with mental disorders

BACKGROUND

Decision-making deficits have been reported in suicide attempters and may be a neuropsychological trait of vulnerability to suicidal behavior. However, little is known about how neural activity is altered in decision-making. This study aimed to investigate the neural responses in suicide attempters with mental disorders during social decision-making. Electroencephalography (EEG) were recorded from 52 patients with mental disorders with past suicide attempts (SAs = 26) and without past suicide attempts (NSAs = 26), as well as from 22 age- and sex- matched healthy controls (HCs) during the Ultimatum Game (UG), which is a typical paradigm to investigate the responses to fair and unfair decision-making.

METHODS

MINI 5.0 interview and self report questionnaire were used to make mental diagnosis and suicide behavior assessment for individuals. Event-related potential (ERP) and phase-amplitude coupling (PAC) were extracted to quantify the neural activity. Furthermore, Spearman correlation and logistic regression analyses were conducted to identify the risk factors of suicidal behavior.

RESULTS

ERP analysis demonstrated that SA patients had decreased P2 amplitude and prolonged P2 latency when receiving unfair offers. Moreover, SA patients exhibited greater negative-going feedback-related negativity (FRN) to unfair offers compared to fair ones, whereas such a phenomenon was absent in NSA and HC groups. These results revealed that SA patients had a stronger fairness principle and a disregard toward the cost of punishment in social decision-making. Furthermore, theta-gamma and beta-gamma PAC were involved in decision-making, with compromised neural coordination in the frontal, central, and temporal regions in SA patients, suggesting cognitive dysfunction during social interaction. Statistically significant variables were used in logistic regression analysis. The area under receiver operating characteristic curve in the logistic regression model was 0.91 for SA/HC and 0.84 for SA/NSA.

CONCLUSIONS

Our findings emphasize that suicide attempts in patients with mental disorders are associated with abnormal decision-making. P2, theta-gamma PAC, and beta-gamma PAC may be neuro-electrophysiological biomarkers associated with decision-making. These results provide neurophysiological signatures of suicidal behavior.

Group Membership Modulates Fairness Consideration Among Deaf College Students-An Event-Related Potential Study

Group interaction is an essential way of social interaction and plays an important role in our social development. It has been found that when individuals participate in group interactions, the group identity of the interaction partner affects the mental processing and behavioral decision-making of subjects. However, little is known about how deaf college students, who are labeled distinctly different from normal hearing college students, will react when facing proposers from different groups in the ultimatum game (UG) and its time course. In this study, we recruited 29 deaf college students who played the UG in which they received extremely unfair, moderately unfair, or fair offers from either outgroup members (normal hearing college students) or ingroup members (deaf college students), while their brain potentials were recorded. The behavioral results showed that group membership did not impact the acceptance rate of deaf college students. But, event-related potential (ERP) analysis demonstrated an enhanced feedback-related negativity (FRN) elicited by ingroup members compared to outgroup members. Importantly, we found that under fairness conditions, deaf college students induced more positive P2 and P3 facing ingroup members compared to outgroup members. Our results demonstrated that group membership may modulate the performance of deaf college students in the UG and the existence of ingroup bias among deaf college students. This provides some evidence for the fairness characteristics of special populations, so that to improve the educational integration of colleges and universities.

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.

Neural processing of equitable and inequitable distributions in 5-year-old children

This study aimed at investigating the neurocognitive correlates of the perception and evaluation of equitable and inequitable distributions in five-year-old children. Children observed one character distributing toys or candies between two recipients. One of the recipients already possessed many resources, and the other possessed just a few. We used event-related potentials to compare brain activity elicited by equitable (the poor receives more) and inequitable (the rich receives more) distribution. On a behavioral level, children evaluated inequitable distribution as worse than equitable and considered the distributor as mean and worthy of punishment when she distributed inequitably as compared to equitably. On the neural level, we expected to find a MFN effect between 250 and 350 ms after picture onset. Instead, we found a frontal positivity (P2), which was greater for inequitable vs. equitable distributions, indicating greater saliency and attentional capture. This was followed by marginally significant greater positivity for equitable distributions between 600 and 1000 ms after picture onset (LPP), which indicates greater allocation of processing resources. Furthermore, a greater LPP was associated with more extreme evaluations for both conditions. This suggests that the more resources children invest in processing the distribution, the more they endorse equity and condemn inequity.

Explicit and implicit markers of fairness preeminence in criminal judges

Achieving justice could be considered a complex social decision-making scenario. Despite the relevance of social decisions for legal contexts, these processes have still not been explored for individuals who work as criminal judges dispensing justice. To bridge the gap, we used a complex social decision-making task (Ultimatum game) and tracked a heart rate variability measurement: the square root of the mean squared differences of successive NN intervals (RMSSD) at their baseline (as an implicit measurement that tracks emotion regulation behavior) for criminal judges (n = 24) and a control group (n = 27). Our results revealed that, compared to controls, judges were slower and rejected a bigger proportion of unfair offers. Moreover, the rate of rejections and the reaction times were predicted by higher RMSSD scores for the judges. This study provides evidence about the impact of legal background and expertise in complex social decision-making. Our results contribute to understanding how expertise can shape criminal judges' social behaviors and pave the way for promising new research into the cognitive and physiological factors associated with social decision-making.

Brain variability in dynamic resting-state networks identified by fuzzy entropy: a scalp EEG study

Objective.Exploring the temporal variability in spatial topology during the resting state attracts growing interest and becomes increasingly useful to tackle the cognitive process of brain networks. In particular, the temporal brain dynamics during the resting state may be delineated and quantified aligning with cognitive performance, but few studies investigated the temporal variability in the electroencephalogram (EEG) network as well as its relationship with cognitive performance.Approach.In this study, we proposed an EEG-based protocol to measure the nonlinear complexity of the dynamic resting-state network by applying the fuzzy entropy. To further validate its applicability, the fuzzy entropy was applied into simulated and two independent datasets (i.e. decision-making and P300).Main results.The simulation study first proved that compared to the existing methods, this approach could not only exactly capture the pattern dynamics in time series but also overcame the magnitude effect of time series. Concerning the two EEG datasets, the flexible and robust network architectures of the brain cortex at rest were identified and distributed at the bilateral temporal lobe and frontal/occipital lobe, respectively, whose variability metrics were found to accurately classify different groups. Moreover, the temporal variability of resting-state network property was also either positively or negatively related to individual cognitive performance.Significance.This outcome suggested the potential of fuzzy entropy for evaluating the temporal variability of the dynamic resting-state brain networks, and the fuzzy entropy is also helpful for uncovering the fluctuating network variability that accounts for the individual decision differences.

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.

Me first: Neural representations of fairness during three-party interactions

One hallmark of human morality is a deep sense of fairness. People are motivated by both self-interest and a concern for the welfare of others. However, it remains unclear whether these motivations rely on similar neural computations, and the extent to which such computations influence social decision-making when self-fairness and other-fairness motivations compete. In this study, two groups of participants engaged in the role of responder in a three-party Ultimatum Game while being scanned with functional MRI (N = 32) or while undergoing high-density electroencephalography (N = 40). In both studies, participants accepted more OtherFair offers when they themselves received fair offers. Though SelfFairness was reliably decoded from scalp voltages by 170 ms, and from hemodynamic responses in right insula and dorsolateral prefrontal cortex, there was no overlap between neural representations of fairness for self and for other. Distinct neural computations and mechanisms seem to be involved when making decisions about fairness in three-party contexts, which are anchored in an egocentric, self-serving bias.

The cognitive and neural mechanisms underlying norm-enforcement behaviors under social observation

Abundant evidence has revealed that social observation could enhance people's norm-enforcement behaviors to norm violators. However, whether such enhancement is strategically reputation-based without changes on awareness of social norms or it is accompanied with strengthened perception of norm violations remains unclear. We aimed to test these two hypotheses using a modified Ultimatum Game (UG). Participants played the UG as responders in the fMRI scanner after being instructed the rules of the game and how the observers monitored their performances during the task. Behavioral results showed that unfair offers were perceived more unfair (decreased fairness ratings) and rejected more often under the condition with social observation than that without observation (the control condition). The changes in fairness ratings predicted the increase of rejection rates between two conditions, which provided more evidence for the latter hypothesis. Neural results demonstrated that right insula and anterior cingulate cortex associated with processing norm violations and/or negative emotions were more activated in response to unfair treatments under social observation relative to the control condition. Furthermore, bilateral anterior insula, anterior cingulate cortex, and right amygdala (an emotional processing structure) showed increased activations with the reduction of fairness ratings under social observation. Besides, compared to the control condition, rejecting unfair trials under social observation induced more left anterior insula activation. These findings indicated that the increase of norm-enforcement behaviors in the UG under social observation was more than a behavioral strategy for social desirability, but a result of enhanced sensitivity to fairness norm violations and unfairness-related negative feelings.

He had it Comin': ERPs Reveal a Facilitation for the Processing of Misfortunes to Antisocial Characters

Human sociality and prosociality rely on social and moral feelings of empathy, compassion, envy, schadenfreude, as well as on the preference for prosocial over antisocial others. We examined the neural underpinnings of the processing of lexical input designed to tap into these type of social feelings. Brainwave responses from 20 participants were measured as they read sentences comprising a randomly delivered ending outcome (fortunate or unfortunate) to social agents previously profiled as prosocial or antisocial individuals. Fortunate outcomes delivered to prosocial and antisocial agents aimed to tap into empathy and envy/annoying feelings, respectively, whereas unfortunate ones into compassion for prosocial agents and schadenfreude for antisocial ones. ERP modulations in early attention-capture (100-200 ms), semantic fit (400 ms), and late reanalysis processes (600 ms) were analyzed. According to the functional interpretation of each of these event-related electrophysiological effects, we conclude that: 1) a higher capture of attention is initially obtained in response to any type of outcome delivered to a prosocial versus an antisocial agent (frontal P2); 2) a facilitated semantic processing occurs for unfortunate outcomes delivered to antisocial agents (N400); and 3) regardless of the protagonist's social profile, an increased later reevaluation for overall unfortunate versus fortunate outcomes takes place (Late Positive Potential). Thus, neural online measures capture a stepwise unfolding impact of social factors during language comprehension, which include a facilitated processing of misfortunes when they happen to occur to antisocial peers (i.e., schadenfreude).

Socially alerted cognition evoked by a confederate's mere presence: analysis of reaction-time distributions and delta plots

We examined aspects of social alerting as induced through the presence of an attentive but non-evaluative confederate on mental efficiency. To this end, individuals were administered with a chained mental-arithmetic task (levels: low vs. high demand) in two contextual conditions (levels: alone vs. presence). In addition, we examined self-report measures of subjective state for purposes of control. As a result, the presence (vs. alone) condition improved (not hampered) processing speed (while error rate remained low overall), and this effect was differentially more pronounced for high (vs. low) demand. Reaction-time distributional analyses revealed that improvements in average performance actually originated from a selective speeding-up in the slower percentiles, indicating that social alerting promotes stability of information-processing throughput. These results challenge prevalent theoretical notions of mere-presence effects as individuals became consistently faster and less vulnerable to commit attention failure. Our findings indicate that social presence promotes not only processing speed but volitional steadiness.

Different Decision-Making Responses Occupy Different Brain Networks for Information Processing: A Study Based on EEG and TMS

This study used large-scale time-varying network analysis to reveal the diverse network patterns during the different decision stages and found that the responses of rejection and acceptance involved different network structures. When participants accept unfair offers, the brain recruits a more bottom-up mechanism with a much stronger information flow from the visual cortex (O2) to the frontal area, but when they reject unfair offers, it displayed a more top-down flow derived from the frontal cortex (Fz) to the parietal and occipital cortices. Furthermore, we performed 2 additional studies to validate the above network models: one was to identify the 2 responses based on the out-degree information of network hub nodes, which results in 70% accuracy, and the other utilized theta burst stimulation (TBS) of transcranial magnetic stimulation (TMS) to modulate the frontal area before the decision-making tasks. We found that the intermittent TBS group demonstrated lower acceptance rates and that the continuous TBS group showed higher acceptance rates compared with the sham group. Similar effects were not observed after TBS of a control site. These results suggest that the revealed decision-making network model can serve as a potential intervention model to alter decision responses.

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.

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.

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.

It's not me, it's you - Differential neural processing of social and non-social nogo cues in joint action

This study used a joint flanker task to investigate differences in processing of social and non-social nogo cues, i.e., between cues indicating that a co-actor should respond and cues signaling that neither actor nor co-actor should respond, using event-related potentials (ERPs) and trial-to-trial response times (RTs). It was hypothesized that a social co-actor's response should be reflected in stronger modulation (slower RTs on subsequent trials; augmented neural responses) for social compared to non-social nogo. RTs and ERPs replicated flanker compatibility effects, with faster responses and increased P3a on compatible trials. In line with the hypotheses, ERPs revealed distinct coding of social and non-social nogo in the conflict-sensitive N2 which showed a compatibility effect only for social nogo, and in the attention/memory-related P3b which was larger for social relative to non-social nogo. The P3a did not distinguish between social and non-social nogo, but was larger for compatible and smaller for go trials. Contrary to our hypotheses, RTs were faster after social relative to non-social nogo. Hence, the representation of the co-actor's response in joint action modulates conflict processing reflected in the N2 and response discrimination and evaluation reflected in the P3b and may facilitate subsequent responses in the context of social versus non-social nogo.