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Abstract 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.

Third-party punishment (TPP) plays an irreplaceable role in maintaining social fairness. Punishment power is a significant area of study within economic games. However, the impact of whether or not the second-party possesses punishment power on TPP remains unexplored. The present study utilizes the high temporal resolution of EEG and time-frequency analysis, intra-barin functional connectivity analysis, inter-brain synchronization (IBS) analysis, and granger causality analysis(GCA) to comprehensively explore the neural mechanism of TPP from the perspective of third-party individual's decision-making and IBS in the real-time social interaction. Time-frequency results found that, the absence of the punishment power activated more theta-band and alpha-band power compare to when second-party has punishment power. When second-party has no punishment power, functional connection results observed stronger functional connectivity in theta band for medium unfair offers between rTPJ and PFC. Dual-brain analysis revealed that when the second-party has no punishment power, there is a significantly higher IBS in the alpha band between the frontal and frontal-central lobes of the second-party and the parietal and parietal occipital lobes of the third-party. GCA results further showed that the direction of IBS from third-party to second-party was significantly stronger than from second-party to third-party. This study demonstrates that the absence of the second-party's punishment power promote TPP, and similar cognitive process of thinking on how to maintain social fairness enhances IBS. The current study emphasizes the influence of punishment power on TPP, broadens the research perspective and contributes crucial insights into maintain social fairness.

Abstract Partner choice promotes competition among individuals to be selected as a cooperative partner, a phenomenon referred to as competitive altruism. We explored whether chimpanzees engage in competitive altruism in a triadic Ultimatum Game where two proposers can send offers simultaneously or consecutively to a responder who can only accept one of the two competing offers. In a dyadic control condition only one proposer at a time could send an offer to the responder. Chimpanzees increased their offers across trials in the competitive triadic, but not in the dyadic control condition. Chimpanzees also increased their offers after being rejected in previous triadic trials. Furthermore, we found that chimpanzees, under specific conditions, outcompete first proposers in triadic consecutive trials before the responder could choose which offer to accept by offering more than what is expected if they acted randomly or simply offered the smallest possible amount. These results suggest that competitive altruism in chimpanzees did not emerge just as a by-product of them trying to increase over previous losses. Chimpanzees might consider how others’ interactions affect their outcomes and engage in strategies to maximize their chances of being selected as cooperative partners.

Stress is a crucial factor affecting social decision-making. However, its impacts on the behavioral and neural processes of females’ unfairness decision-making remain unclear. Combining computational modeling and functional near-infrared spectroscopy (fNIRS), this study attempted to illuminate the neurocomputational signature of unfairness decision-making in females. We also considered the effect of trait stress coping styles. Forty-four healthy young females (20.98 ± 2.89 years) were randomly assigned to the stress group (n = 21) and the control group (n = 23). Acute psychosocial stress was induced by the Trier Social Stress Test (TSST), and participants then completed the one-shot ultimatum game (UG) as responders. The results showed that acute psychosocial stress reduced the adaptability to fairness and lead to more random decision-making responses. Moreover, in the stress group, a high level of negative coping style predicted more deterministic decision. fNIRS results showed that stress led to an increase of oxy-hemoglobin (HbO) peak in the right temporoparietal junction (rTPJ), while decreased the activation of left middle temporal gyrus (lMTG) when presented the moderately unfair (MU) offers. This signified more involvement of the mentalization and the inhibition of moral processing. Moreover, individuals with higher negative coping scores showed more deterministic decision behaviors under stress. Taken together, our study emphasizes the role of acute psychosocial stress in affecting females’ unfairness decision-making mechanisms in social interactions, and provides evidences for the “tend and befriend” pattern based on a cognitive neuroscience perspective.

To better understand the individual differences in fairness, we used event-related potentials (ERPs) to explore the fairness characteristics of deaf college students through the ultimatum game task. Behaviorally, the significant main effect of the proposal type was found, which meant both deaf and hearing college students showed a lower acceptance rate for the more unfair proposal. Interestingly, we found a significant interaction between group and proposal type in the early stage (N1). Moreover, in the deaf college group, N1 (induced by moderately and very unfair proposals) was significantly larger than that of fair proposals. However, we found that deaf college students had smaller amplitudes on P2 and P3 than hearing college students. These results suggested that deaf college students might pursue more equity strongly so they are more sensitive to unfair information in the early stage. In a word, we should provide more fair allocations for deaf college students in our harmonious society.

Inarguably, humans perform the richest plethora of prosocial behaviours in the animal kingdom, and these are important for understanding how humans navigate their social environment. The success and failure of strategies human players devise also have implications for determining long-term socio-economic/evolutionary fitness. Following the footsteps of Press and Dyson (2012), I implemented their evolutionary game-theoretic modelling from Iterated Prisoner’s Dilemma (a behavioural economic probe of interpersonal cooperation) and re-analysed already published data on human proposer behaviour in the Ultimatum Game (a behavioural economic probe of altruistic punishment) involving 50 human participants versus stochastic computerized opponents with prosocial and individualistic social value orientations. Although the results indicate that it is more likely to break cycles of mutual defection in ecosystems in which humans interact with individualistic opponents, analysis of social-economic fitness at the Markov stationary states suggested that this comes at an evolutionary cost. Overall, human players acted in a significantly more cooperative manner than their opponents, but they failed to overcome extortion from individualistic agents, risking ‘extinction’ in 70% of the cases. These findings demonstrate human players might be short-sighted, and social interactive decision strategies they devise while adjusting to different types of opponents may not be optimal in the long run.

IntroductionHuman decision-making pertaining to gains compared to those pertaining losses is shown to be quite different. However, mixed evidence is provided regarding the effect on the decision-makers' prosocial behaviors; that is, losses are shown to either increase or decrease prosocial behaviors. In this context, the effect of social norms on observed behavior can play a crucial role.MethodsTo examine this aspect in more detail, we conducted incentivized ultimatum game experiments and analyzed data from three treatments, the control treatments (without specific norm focus), and two different norm-focus treatments (“average behavior” treatment and “self-interested behavior” treatment). In total, 550 participants took part in our experiment. Basically, we found no significant difference between the division of gains and losses in the “control” and “self-interested behavior” treatments.Results and discussionHowever, we found such a difference in the “average behavior” treatment. In addition, we found that inducing a norm focus leads to less variance in proposers' behavior and a greater concentration of their demands around the induced norm in the “average behavior” treatment. In contrast, we found a higher variance in proposers' behavior in the “self-interested behavior” treatment. In terms of responders' behaviors, we observed a tendency toward a higher frequency of responders' rejections in the loss domain compared to the gains domain.

Ran-Ran Zhang,1,2,* Yu-Qing Meng,1,* Yan Tian,1 Tao Zou3 1School of Medical Humanities, Guizhou Medical University, Guizhou, 550004, People’s Republic of China; 2Researcher, Guizhou Health Development Research Center, Guizhou, 550004, People’s Republic of China; 3Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guizhou, 550004, People’s Republic of China*These authors contributed equally to this workCorrespondence: Tao Zou, Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guizhou, 550004, People’s Republic of China, Tel +8613985400734, Email zoutaozou@tom.comPurpose: Most studies have supported the view that individuals prefer to reward the in-group and discriminate against the out-group in response to unfair offers in the Ultimatum Game. However, the current study advanced a different view, that is, the “black sheep effect”, in which in-group members were punished more severely compared with out-group members. This study aimed to incorporate proposer identity and allocation motive as possible explanations for offer rejection.Methods: In the current study, the in-group and out-group identities were distinguished by their health condition, and the allocation motive was defined according to its benefit maximization. With a total of 89 healthy college student participants, a mixed design of 2 (proposer identity: out-group vs in-group) × 2 (allocation motive: selfish vs random) × 2 (offer type: unfair vs fair) was used in the Ultimatum Game. Event-related potential (ERP) technology was used, and ERPs were recorded while participants processed the task.Results: The behavioral result showed that the “black sheep effect” was found on the fair offer when a random allocation motive was used. Our ERP result suggested that feedback-related negativity (FRN) and P300 were modulated by proposer identity but not by allocation motive. However, the allocation motive interacted with proposer identity affecting FRN and P300 when the fair offer was proposed.Conclusion: These findings demonstrated that the “black sheep effect” was related to the experience of the out-group member, such as disadvantage or distress, but it was also modulated by allocation motive. Meanwhile, the out-group (depressed college students) captured more attention because they violated individual expectations, according to the P300. This finding plays an integral role in understanding the mechanism of response to the “black sheep effect”.Plain Language Summary: People prefer to receive fair offers compared to unfair offers, but they are more tolerant to in-group members compared with out-group members when facing unfair offers. However, what would you do if you knew the in-group members were making you the smallest offer possible with a self-interested motive to maximize their own gains? We used the Ultimatum Game (UG) to explore this issue. We invited 89 colleges to participate in this study, and they were randomly divided into in-group member, out-group member, selfish motive, and random motive groups. Then, we used event-related potential (ERP) technology to examine cognitive processing. We found the “back sheep effect” on the fair offer, which means that people prefer to accept the out-group member’s offer when they had a random motive. We also found different feedback-related negativity (FRN) and P300 between the in-group and out-group members. In addition, the “black sheep effect” was found in the fair offers when the proposer presented a random motive. This finding plays an important role in understanding the mechanism of response to fair or unfair offers.Keywords: in-group, out-group, ultimatum game, event-related potential technique, allocation motive, feedback-related negativity, P300

IntroductionThe present study was designed to examine the effect of monetary and non-monetary endowment on lying by men and women in the Ultimatum Game. Another goal was to examine to what extent the Self-Reported Lying Scale (SRLS), described here for the first time, predicts lying in the Ultimatum Game.MethodsExaminees (162, 82 women) were allocated to four experimental conditions in a 2 × 2 factorial design. Two endowment conditions (money and game points) were crossed with two sex conditions (men and women). Participants underwent an Ultimatum Game in which they were permitted to conceal part of the endowment from an unidentified partner. Finally, participants completed the SRLS.ResultsThe results indicated that more cash than points were concealed from the partner, and men concealed more of their endowment than women. We further defined fake fairness in sharing that combined hiding a more significant portion of the endowment from the partner while presenting fair sharing of the remaining award. We found more fake fairness when money was shared than when points were concealed. Fake fairness is more significant for men than for women. For money and points alike, concealment was predicted by the global score of the SRLS and its five subscales (self-assessed lying ability, lie detection ability, the use of reason in lying, lie acceptability, and lie frequency).DiscussionIt was suggested that a monetary endowment is more sensitive to lying than game points and involves more fake fairness. Nevertheless, the differences are quantitative, and the same response pattern exists in the two endowment conditions. Replacing money with points is a proper solution whenever a monetary endowment presents difficulties. It was further suggested that sex differences exist in lying using an asymmetric information UG, where proposers were permitted to mislead responders about their endowment. Finally, the SRLS may contribute to a better understanding of the question of who lies.

Objective: we analyzed decision-making under stress by manipulating salivary cortisol levels. Theoretical background: literature dedicated to the relationship between stress and decision-making is still inconclusive. Studies have found that when dealing with stressful decisions, people will respond with a greater propensity for opportunistic behavior. However, stress might also decrease the potential for deception when the decision requires strategic/analytical responses. Method: we implemented a laboratory experiment using the ultimatum game with asymmetric information, in which only the first mover was fully informed about the size of the endowment. Our experiment compared the decisions of subjects who received a stress stimulus from an adapted Trier social stress test for groups (TSST-G) protocol with a control group. Results: we found that under stress, proposers transferred more to responders. In contrast, non-stressed players were more likely to take advantage of information asymmetry by choosing lower strategic offers, which is consistent with the so-called ‘hide behind a small cake’ effect. Regression analysis also indicated that larger offers are not necessarily associated with increased prosocial motives since stressed proposers became more confident about the responder’s ability to guess the true endowment, which decreased their incentive to take advantage of the aforementioned effect. Conclusions: one possible effect of stress could be an increase in risk perception, decreasing the ability to make strategic decisions. The stressful condition might have rendered our participants less capable of realizing the ‘hide behind a small cake’ potential of the game, leading them to make more conservative offers when compared to the control group.

In this study, we measured how people would take advantage of others’ misinformation, when the financial incentive size changes in economic games. We conducted a laboratory experiment based on game theory, using a modified version of the ultimatum game, where proposers had the opportunity to manipulate the responder’s beliefs by the use of ‘hide behind the small cake’ strategy. Our results contradict the selfish rationality model predictions. Intermediary financial incentives led people to adopt extremes strategies of pure fair/selfish allocation. Greater levels of financial incentive reduced the full expropriation strategy and at the same time, reduced the presence of fair offers, which suggests an interesting interaction between opportunism and psychological costs of lying. The results showed that opportunism is hugely context-dependent and people will update their decision regarding opportunism in accordance with the financial size incentive. Thus, the same person can behave differently depending on the financial value involved and will not necessarily be more selfish when the financial amount increases.

Evolutionary game theory involves multiple disciplinary sciences and has enormous scientific value and promising applicability. Collective behavior is an important topic of interdisciplinary study. Ethology has shown the ubiquity of collective behavior and has proven the rationality of evolutionary theory in explaining the emergence of collective behavior. The recent development of complex network theory offers a convenient framework for describing game interactions and competition relationships among individuals. The combination of evolutionary games and complex networks, particularly, evolutionary game theory in a complex network, has been attracting growing interest from different fields. It has undergone substantial development, especially in quantitative analysis of two-strategy competition. Under this framework, the complex network represents the population structure, and the game describes interactions between individuals. On the basis of the methodology from network science, stochastic process, and statistical physics, the framework mainly focuses on how population structures, individual behavior patterns, and interacting environments influence the emergence of collective behavior. In this paper, the mechanisms for the evolution of cooperation were given under the framework of evolutionary game, including kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. Recently, the effects of individual heterogeneity and environmental feedback on cooperation had attracted growing interest. Next, five main theoretical methods were addressed for analyzing the evolutionary game in complex networks, including the \begin{document}$ \sigma $\end{document}- dominance rule, the coalescing theory, the pairwise approximation, the coalescing random walk theory, and the adaptive dynamics. Particularly, the recently proposed coalescing random walk theory is suitable for analyzing the dynamics of any network structure and any update rule. Then, the studies on the evolution of fairness in ultimatum games were presented, and reasonable resource allocation is the key factor for social stability, economic development, and individual health. Finally, the challenges and further directions of studying ultimatum games in a complex network were summarized.

According to decades of research, whether negotiations succeed depends on how much of the stake each person will get. Yet, real-world stakes often consist of resources that vary on quality, not just quantity. While it may appear obvious that people should reject qualitatively inferior offers, just as they reject quantitatively unequal offers, it is less clear why. Across three incentive-compatible studies (N = 1,303) using the ultimatum game, we evaluate three possible reasons for why people reject qualitatively unequal negotiation offers (that are 50% of the stake): fairness, mere inequality, or badness. Data across the three studies are consistent with the fairness account. Casting doubt on the possibility that people reject qualitatively unequal offers merely because they are ‘bad’, Studies 1 and 2 found that participants were more likely to reject the same coins when these were inferior (e.g., 200 × 5¢ coins) to the negotiation partner’s coins (e.g., 5 × $2 coins) than when both parties received the same undesirable coins (e.g., both received 200 × 5¢ coins). Supporting a fairness explanation, rejection rates of the qualitatively inferior offer were higher when the proposal came from a human (vs. a computer), suggesting that rejection stemmed in part from a desire to punish the negotiation partner for unfair treatment (Study 3). Nevertheless, some participants still rejected the unequal offer from a computer, suggesting that mere inequality matters as well. In sum, the findings highlight that quality, not just quantity, is important for attaining fair negotiation outcomes.

In two studies, we tested the power of revenge as a justification mechanism that enables people to cheat with a clear conscience. Specifically, we explored the effects of prior dishonesty and unfairness towards participants on their subsequent moral behavior, as well as the physiological arousal associated with it. To this end, we employed a two-phase procedure. In the first phase, participants played one round of a bargaining game (the Ultimatum game in Study 1 and the Dictator game in Study 2) in which we manipulated whether the players had been treated (un)fairly and (dis)honestly by their opponent. In the second phase, they did a perceptual task that allowed them to cheat for monetary gain at the expense of their opponent from the first phase. In Study 1, participants also took a lie detector test to assess whether their dishonesty in the second phase could be detected. The behavioral results in both studies indicated that the opponent’s dishonesty was a stronger driver than the opponent’s unfairness for cheating as a form of retaliation. However, the physiological arousal results suggest that feeling mistreated in general (and not just cheated) allowed the participants to get revenge by cheating the offender while dismissing their associated guilt feelings.

In two studies, we tested the power of revenge as a justification mechanism that enables people to cheat with a clear conscience. Specifically, we explored the effects of prior dishonesty and unfairness towards participants on their subsequent moral behavior, as well as the physiological arousal associated with it. To this end, we employed a two-phase procedure. In the first phase, participants played one round of a bargaining game (the Ultimatum game in Study 1 and the Dictator game in Study 2) in which we manipulated whether the players had been treated (un)fairly and (dis)honestly by their opponent. In the second phase, they did a perceptual task that allowed them to cheat for monetary gain at the expense of their opponent from the first phase. In Study 1, participants also took a lie detector test to assess whether their dishonesty in the second phase could be detected. The behavioral results in both studies indicated that the opponent's dishonesty was a stronger driver than the opponent's unfairness for cheating as a form of retaliation. However, the physiological arousal results suggest that feeling mistreated in general (and not just cheated) allowed the participants to get revenge by cheating the offender while dismissing their associated guilt feelings.

IntroductionPeople’s forecasts of their future emotions play an essential role in their behavior and experience of well-being. However, their emotional reactions may fall short of what they expect, which has implications for subsequent decision making. The current paper investigated the accuracy of affective forecasting about resource allocations and how this (in)accuracy predicts future allocation decisions.MethodsTwo experimental studies were conducted. Study 1 (N = 84) examined the extent to which people can accurately predict how allocation decisions will feel using an ultimatum game on the part of the allocator. Study 2 tested whether the affective forecasting bias affects future allocation decisions, with 192 participants playing a two-round ultimatum game on the part of allocators.ResultsStudy 1 found an affective forecasting bias, and people anticipated more powerful emotional reactions to both positive and negative allocation events than they actually experienced when the events occurred. Study 2 found that increased affective forecasting bias resulted in less generous decisions in positive event conditions and more generous decisions in negative event conditions.DiscussionThese results extend previous findings concerning affective forecasting bias and the feelings-as-information model in resource allocation interactions and show that the difference between anticipated and experienced emotion is also informative in allocation decisions. The results suggest that being more cautious when forecasting positive outcomes and more optimistic when forecasting negative outcomes can be beneficial to one’s well-being.

According to the dual-system theories, the decisions in an ultimatum game (UG) are governed by the automatic System 1 and the controlled System 2. The former drives the preference for fairness, whereas the latter drives the self-interest motive. However, the association between the contributions of the two systems in UG and the cognitive process needs more direct evidence. In the present study, we used the process dissociation procedure to estimate the contributions of the two systems and recorded participants eye movements to examine the cognitive processes underlying UG decisions. Results showed that the estimated contributions of the two systems are uncorrelated and that they demonstrate a dissociated pattern of associations with third variables, such as reaction time (RT) and mean fixation duration (MFD). Furthermore, the relative time advantage (RTA) and the transitions between the two payoffs can predict the final UG decisions. Our findings provide evidence for the independent contributions of preference for fairness (System 1) and self-interest maximizing (System 2) inclinations to UG and shed light on the underlying processes.

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

The present research investigated the role of sex in the effect of vocal attractiveness on fairness judgment in a two-person Ultimatum Game. Each participant in the game decided whether to accept offers from a proposer who was either associated with an attractive or unattractive voice. The results showed that while participants were more likely to accept fair offers, they would also accept some unfair offers that were associated with an attractive voice. This effect of vocal attractiveness was more clearly shown by female participants, although all male and female participants took longer to make a decision when an attractive voice was associated with an offer, regardless of whether the voice was from the same sex or the opposite sex. Overall, the results inform the role of sex in the effect of vocal attractiveness and further confirm the beauty premium effect on economic bargaining, where people with an attractive voice would benefit.

We develop a modified ultimatum game, in which the proposer gives two offers, and the responder selects one offer out of the two without seeing them. Then, the selected offer becomes the relevant offer, and the unselected offer becomes the irrelevant one. Finally, the responder evaluates the fairness of the pair of offers and makes a hypothetical decision whether to accept or reject the relevant offer. For most of our subjects, the level of the irrelevant offer positively affects fairness perceptions and willingness to accept, even though the irrelevant offer cannot be accepted. The reason is that the irrelevant offer does signal the proposer’s intentions. Most responders give more weight to the relevant offer than to the irrelevant offer in evaluating fairness and in the willingness to accept. We call this effect the relevance effect. This effect is expected when considering the willingness to accept. However, it is unclear why the relevant offer should carry more weight when evaluating fairness, because the proposer makes the two offers together without knowing which one will become the relevant one. Therefore, this behavior can be considered a bias in fairness evaluations.

We develop a modified ultimatum game, in which the proposer gives two offers, and the responder selects one offer out of the two without seeing them. Then, the selected offer becomes the relevant offer, and the unselected offer becomes the irrelevant one. Finally, the responder evaluates the fairness of the pair of offers and makes a hypothetical decision whether to accept or reject the relevant offer. For most of our subjects, the level of the irrelevant offer positively affects fairness perceptions and willingness to accept, even though the irrelevant offer cannot be accepted. The reason is that the irrelevant offer does signal the proposer’s intentions. Most responders give more weight to the relevant offer than to the irrelevant offer in evaluating fairness and in the willingness to accept. We call this effect the relevance effect. This effect is expected when considering the willingness to accept. However, it is unclear why the relevant offer should carry more weight when evaluating fairness, because the proposer makes the two offers together without knowing which one will become the relevant one. Therefore, this behavior can be considered a bias in fairness evaluations.

Relevance of the research topic. A study of player behavior can answer a large number of questions related to motivation and driving forces of negotiators. Particularly acute is the problem of understanding the minimum expectations of the negotiating parties, the willingness to accept worse conditions compared to the counterparty. An important role has the perception of "fairness" in the behavior of players. Understanding these mechanisms will increase the level of social development by increasing the effectiveness of negotiations and coherence of the participant’s behavior. Formulation of the problem. We have summarized and systematized the results of previous research on the influence of various factors on the behavior of players and, as a consequence, on the results of the Ultimatum game. In particular, the influence of the following factors was studied: the amount of money that will be distributed among the players; anonymity and the possibility of punishing the counterparty. Analysis of recent research and publications. There are a large number of publications on the behavior of players in the Ultimatum game, which explore the role of changing factors and their impact on the results of the game. A great contribution to the study of the Ultimatum game have made the works of Güth et al. (1982), G. Bolton and R. Zwick (1995), S. Andersen et al. (2011) and R. Slonim and E. Roth (1998). The purpose and the objectives of the study. The purpose of the study is to substantiate, to generalize, as well as to compare the empirical results of the Ultimatum game to the theoretical results according to classical economic theory. The objectives of the article are to study the influence of factors of anonymity, punishment, and stake size on the behavior of the players. Research methodology. Classical economic theory and behavioral economics constitute the methodological basis for this study. Methods of comparison, analysis and synthesis, induction and deduction are used. Presentation of the main material (results of work). The Ultimatum game, its possible results according to the classical economic theory, its empirical results, revealed by Güthet al. (1982) are studied. Also, the influence of the following factors is surveyed: the amount of money that should be distributed among the players, anonymity and the possibility of punishing the counterparty. Field of application of results. The results of the study can be applied in management, public administration, economics, capital markets. Conclusions according to the article. The stake size, anonymity, and punishment have a decisive influence on the behavior of players in the Ultimatum game. The study demonstrates a significant effect of the relative size of the stake compared to the absolute size offered to game participants. Anonymity has a significant but less noticeable effect on the outcome of the game, compared to the possibility of the second player punishing the first for, in his opinion, an unfair offer. In the complete absence of the possibility of punishment, the behavior of players approaches the theoretical economic theory.

Studies have demonstrated the influence of the cultural values of individualism and collectivism on individuals’ economic behavior (e.g., competition and trade). By using individualistic and collectivistic texts to prime participants’ minds in a lab experiment, we investigated the impact of the cultural values of individualism and collectivism on allocation behavior in an ultimatum game (UG) and dictator game (DG). In the dictator game, we found that participants in the collectivism-priming condition reported a slightly higher mean offer than in the individualism-priming condition, and participants had an average higher acceptance rate of the proposers’ offer in the collectivism-priming (vs. individualism-priming) condition in the ultimatum game. Our findings suggest that participants exhibit more altruistic allocation behavior and are more tolerant of unfair allocation behavior after being primed by the collectivistic (vs. individualistic) texts. In comparison with participants who did not undergo initiation, we also found that Chinese participants who had been influenced by collectivist values for a long time remained unaffected after the initiation of collectivism, but shifted their allocation behavior (i.e., showed decreased altruistic allocation behavior and reduced tolerance of unfair allocation behavior) when individualism was primed.

We examine the 1914-1918 creation of the Kingdom of Serbs, Croats and Slovenes as a form of the ultimatum game. The negotiations among the Serbian Cabinet and the Yugoslav Committee representatives of the Habsburg Souths Slavs from 1914-1918 exemplify three versions of this game. The first version is a typical (rational choice) type of the ultimatum game in which the Receiver is satisfied with any offer by the Proposer. The second version is an instance of behavioral game theory. When the Proposer gives an unfair offer, it provokes an emotional reaction in the Receiver who will reject it at the cost of harming themselves. We observe this behavior in the emotional behavior of Frano Supilo, a Croat and one of the leaders of the Yugoslav Committee. The third version of the behavioral ultimatum game can be observed in the behavior of Serbian Prime Minister Nikola Pašić who opposed any concessions to the Yugoslav Committee, thus giving an ultimatum to the Croat side to accept the Serbian offer or remain with nothing, which was harmful to the Serbian side, too. This example is important because it produces two conclusions. First, historical games are often a mixture of several versions. Second, Proposers, too, can have an emotional reaction and give an offer that can hurt themselves. This aspect of the ultimatum game is less mentioned because it is difficult to simulate in experiments.

Abstract Background Based on social comparison theory, two experiments were conducted to explore the effects of depression and social comparison on adolescents, using the ultimatum game (UG). Methods Before the formal experiment began, a preliminary experiment tested the effectiveness of social comparison settings. This study used the UG paradigm to explore adolescents’ social decision-making in the context of gain and loss through two experiments. These experiments were designed as a 2 (group: depressive mood group, normal mood group) × 2 (social comparison: upward, downward) × 3 (fairness level: fair 5:5, unfair 3:7, extremely unfair 1:9) three-factor hybrid study. Results (1) The fairer the proposal was, the higher the sense of fairness participants felt, and the higher their acceptance rate. (2) The acceptance rate of the participants for downward social comparison was significantly higher than that for upward social comparison, but there was no difference in fairness perception between the two social comparisons. (3) Under the context of gain, the acceptance rate of the depressive mood group was higher than that of the normal mood group, but there was no difference in the acceptance rate between the depressive mood group and the normal mood group under the loss context. Depressive mood participants had more feelings of unfairness in the contexts of both gain and loss. (4) The effects of depressive mood, social comparison and the fairness level of distribution on social decision-making interact. Conclusions The interaction of social comparison, depressive mood and proposal type demonstrates that besides one’s emotion, cognitive biases and social factors can also have an effect on social decision-making. These findings indicate that behavioral decision boosting may provide an avenue for appropriate interventions in helping to guide adolescents to make social decisions.

Past research showed that the ability to focus on one’s internal states (e.g., interoceptive ability) positively correlates with the self-regulation of behavior in situations that are accompanied by somatic and/or physiological changes, such as emotions, physical workload, and decision-making. The analysis of moral oriented decision-making can be the first step for better understanding the legal reasoning carried on by the main players in the field, as lawyers are. For this reason, this study investigated the influence of the decision context and interoceptive manipulation on the moral decision-making process in the legal field gathering the responses of two groups of lawyers. A total of 20 lawyers were randomly divided into an experimental group (EXP), which was explicitly required to focus the attention on its interoceptive correlates, and a control group (CON), which only received the general instruction to perform the task. Both groups underwent a modified version of the Ultimatum Game (UG), where are presented three different moral conditions (professional, company, and social) and three different offers (fair, unfair, and equal). Results highlighted a significant increase of Acceptance Rate (AR) in those offers that should be considered more equal than fair or unfair ones, associated with a general increase of Reaction Times (RTs) in the equal offers. Furthermore, the interoceptive manipulation oriented the Lawyers toward a more self-centered decision. This study shows how individual, situational, contextual, and interoceptive factors may influence the moral decision-making of lawyers. Future research in the so-called Neurolaw field is needed to replicate and expand current findings.

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.

People show a strong aversion to inequality and are willing to sacrifice their own interests to punish violations of fairness norms. Empirical research has found that group membership could influence the fairness judgment and norm enforcement of the individuals but has shown inconsistent findings and has not focused much on the potential moderators. Here, the two studies aimed to investigate whether victim sensitivity and proposal size moderate the impact of group membership on reactions to unfair proposals. In both studies, the participants with different victim sensitivity (low vs. high group) played the hypothetical (Study 1) and incentivized (Study 2) ultimatum game under the intragroup and intergroup condition and indicated their responses to the different proposals. Results showed that, regardless of the victim sensitivity, ingroup member is often given preferential and positive treatment. Low victim sensitive persons are more likely to accept unfair offers from the ingroup than the outgroup, while this effect was attenuated for those with high victim sensitivity, especially for highly ambiguous unfair offers (offer 6:4 in Study 1 and 8:2 in Study 2). Moreover, the ingroup favoritism score for ambiguous unfair offers was smaller for high compared with the victim sensitivity group. Taken together, the victim sensitivity, and proposal size could moderate the ingroup favoritism on responses to unfairness.

Abstract Background Individuals with bipolar disorder show mood instability, including heightened anger and impulsivity. The Ultimatum Game (UG) is a tool used to evaluate emotional and social decision‐making strategies. We investigated behavioral and electrophysiological responses to subjectively fair or unfair offers in the UG in patients with bipolar I disorder. Methods Twenty‐four manic patients, 20 euthymic patients, and 30 healthy controls participated in this study. We analyzed their behaviors and collected electroencephalography data with which to analyze feedback‐related negativity (FRN) as they played in the UG as responders. Results Manic patients exhibited significantly higher rejection rates for unfair offers than euthymic patients and healthy controls. Healthy individuals exhibited a greater (i.e., more negative) FRN amplitude in response to unfair offers than to fair offers, whereas euthymic patients exhibited a greater FRN amplitude in response to fair offers compared with unfair offers. Manic patients exhibited no difference in FRN amplitudes between fair and unfair offers. Conclusions The current data suggest that different behavioral responses and FRN amplitude patterns can be associated with characteristic manifestations of mood instability in manic bipolar patients. In addition, electrophysiological alterations in response to unfair offers may be a trait abnormality independent of mood state.

People tend to voluntarily sacrifice their own interests to reject unfair proposals, and this behaviour is affected by group affiliation. While group bias is a well-established phenomenon, its direction is still unclear, and little attention has been given to possible moderating factors. In two studies, we manipulate participants’ ingroup identification and investigate whether and how individuals with various levels of ingroup identification react differently to unfairness from ingroups and outgroups during an incentivized (Study 1, N = 46) and hypothetical (Study 2, N = 332) ultimatum game. The results show that participants display a strong preference for their own group. High identifiers tend to accept unfair proposals from ingroups compared to outgroups, whereas this effect is nonsignificant for low identifiers, especially for moderately unfair treatment (offer 7:3). Moreover, higher identification tends to be accompanied by higher ingroup positive expectation, which then leads to greater ingroup favouritism for an offer of 7:3. These results imply that ingroup identification can enhance group favouritism during fairness norm enforcement through ingroup positive expectation.

The ability to form groups to overcome problems has been crucial for the evolution of human beings. To favour the formation of cooperating groups, one of the mechanisms developed is the inter-group bias, namely the tendency of individuals to favour members of their group and hinder the external ones. It is the cognitive equivalent of the "green beard effect" in evolutionary biology, introduced by Hamilton and popularized by Dawkins, for which a group can profit of the altruistic behaviour of its members. Here, we use a behavioural model based on the Ultimatum Game, to shed light on how this behaviour cloud has been stabilized in the human population, estimating the magnitude of favouritism needed to overcome selfish individuals. Through both numerical simulations and analytic approaches, we study how a community of collectivist and individualist agents evolves. The key factor is the mechanism for the evolution of the population, i.e., the replacement of the poor-performing individuals. In the case of replacement by the reproduction of existing individuals, we observe a smooth phase transition and no coexistence. If the replacement is random, the transition smooths, and coexistence is possible. We developed analytical approaches for these two cases and performed numerical simulations. Although analytical calculations support the behaviour emerging from simulations, some differences ask for more refined treatments.

Abstract Background Anorexia nervosa (AN) patients are assumed to express high levels of guilt and envy. Ultimatum game (UG) is a standard behavioral task that focuses on interpersonal behavior when splitting a sum of money between two players. UG studies consistently demonstrate that people tend to decrease their inequity in outcomes, one explanation being that economically irrational decision-making may partly arise from the emotions guilt and envy. We assumed that AN patients would perform excessively fair in UG, reflecting high guilt and envy. Methods We utilized UG to investigate the characteristics of guilt and envy among 24 Japanese AN patients and 22 age-matched healthy controls (HC). The relation between the outcome of UG and decision strategy confirmed by post-experimental questionnaires was analyzed. Results As proposer, AN offered a larger amount to the responder compared with HC (p = 0.002) while, on the other hand, as responder, AN demanded much higher allocation to accept the offer compared with HC (p = 0.026). Regarding the strategy as responder, AN put more emphasis on fairness and less emphasis on monetary reward compared with HC (p = 0.046, p = 0.042, respectively). Conclusions The results indicate that Japanese AN patients demonstrate strong preference for fairness, with high guilt and high envy. High sensitivity to guilt and envy of AN patients can affect not only their own behavior concerning eating attitude and body shape, but also decision-making in interpersonal situations. Behavioral experimental settings among social situations will enable us to evaluate and help actual decision-making in the real life of patients.

Introduction Individuals with autism spectrum condition (ASC) frequently report difficulties in detecting changes in social situations, which considerably hinder interpersonal communications. Objectives To better understand the features of detecting changes in social situations among individuals with ASC. Methods Individuals with ASC (N=24) and typical development (TD) (N=24) were included. To examine participants’ sensitivity to situational contexts, we conducted an economic-game task: a modified computer version of the ultimatum game (mod-UG). In UG, two players were offered a chance to win 10 coins after dividing it amongst themselves. The proposer suggests how to split the sum and the responder can accept or reject the deal. After practice, all participants played the role of responders with an imaginary proposer. Participants had to decide whether to accept or reject proposers’ fair/unfair offers. In our mod-UG, additional condition was included that involved intentionality considerations: Unfair offers were displayed with another identical unfair offer. This emphasized the proposers’ inevitable situation of unfair offers. Subsequently, we conducted a 2×2 repeated-measures ANOVA (unfair offers with/without additional cues)×(ASC/TD). Results Participants indeed accepted unfair offers significantly more frequently when the other player’s unfair proposal was unavoidable in cue-added conditions, when compared to unfair offers in no-cue conditions. This suggested that participants considered their opponent’s perspective more attentively in cue-added conditions. However, this effect was significantly decreased in the ASC-group (p

In everyday life, assumptions about our peers' as well as our own personality shape social interactions. We investigated whether self-rated personality and inferences drawn from partners' faces influence economic decisions. Participants (N = 285) played the trust game in the role of the trustor as well as the ultimatum game in the role of the proposer and interacted with trustees and receivers represented by prototypical personality faces. Participants also evaluated both their own traits and the personality of the faces. In the trust game, trustees represented by faces rated higher on agreeableness yielded higher transferred amounts. This effect was more pronounced for trustors low on dispositional trust, whereas trustors high on dispositional trust did not relate their decisions to the faces. Trustees represented by faces rated higher on conscientiousness yielded higher transferred amounts only for trustors high on dispositional anxiety. In the ultimatum game, receivers represented by faces rated higher on conscientiousness yielded lower offers only for proposers high on dispositional assertiveness. These results extend previous findings on the inferences drawn from facial features and the influence of personality on decision making. They highlight the importance of considering the personality of both interaction partner, as well as potential interactions of players' traits.

Objective wealth plays an important role in social interaction and economic decision making. Previous studies indicate that objective wealth of others may influence the way we participate in resources allocation. However, the effect of objective wealth on responses to fairness-related resource distribution is far from clear, as are the underlying neural processes. To address this issue, we dynamically manipulated proposers’ objective wealth and analyzed participants’ behavior as responders in a modified Ultimatum Game, during which event-related potentials were recorded. Behavioral results showed that participants were prone to reject unfair proposals although that rejection would reduce their own benefit. Importantly, participants were more likely to accept unfair offers from proposers with low objective wealth than from proposers with high objective wealth, with a drastic increase in acceptance rates of unfair offers from 32.79 to 50.59%. Further electrophysiological results showed that there was significantly enhanced feedback-related negativity amplitude toward proposers with high (relative to low) objective wealth for unfair offers. Furthermore, the late frontal negativity amplitude was larger for all the conditions which are not high-fair, which might be the only option that did not elicit any ambiguity. These findings suggest a strong role of proposers’ objective wealth in modulating responders’ behavioral and neural responses to fairness.

A considerable share of the literature on the evolution of human cooperation considers the question why we have not evolved to play the Nash equilibrium in prisoners’ dilemmas or public goods games. In order to understand human morality and pro-social behaviour, we suggest that it would actually be more informative to investigate why we have not evolved to play the subgame perfect Nash equilibrium in sequential games, such as the ultimatum game and the trust game. The ‘rationally irrational’ behaviour that can evolve in such games gives a much better match with actual human behaviour, including elements of morality such as honesty, responsibility and sincerity, as well as the more hostile aspects of human nature, such as anger and vengefulness. The mechanism at work here is commitment, which does not need population structure, nor does it need interactions to be repeated. We argue that this shift in focus can not only help explain why humans have evolved to know wrong from right, but also why other animals, with similar population structures and similar rates of repetition, have not evolved similar moral sentiments. The suggestion that the evolutionary function of morality is to help us commit to otherwise irrational behaviour stems from the work of Robert Frank (American Economic Review, 77(4), 593–604, 1987; Passions within reason: The strategic role of the emotions, WW Norton, 1988), which has played a surprisingly modest role in the scientific debate to date.

Background: The influence of emotional feedback on social decision-making situations is an omnipresent part of social interaction. Complementing existing research on the impact of approach- and avoidance-related personality traits, we examined the role of sub-clinical depression and fear of negative social evaluation in a modified ultimatum game. Methods: Different proposer identities reacted with distinct affective facial expressions to the acceptance and rejection of monetary offers in the ultimatum game. Facial expressions of proposers were relevant for depression and anxiety: A smile in response to acceptance or angry and sad feedback in response to rejection. Results: People with higher symptoms of depression rejected more offers when the offer magnitude increased. Both, individuals with symptoms of depression and fear of negative evaluation approached sad feedback by rejecting more offers. At the neural level, positive emotional feedback (i.e., a smiling face) was linked to a reward positivity, which did not occur in participants with higher symptoms of depression. Limitations: Since our paradigm implies a decision-dependent feedback pattern, the negative feedback might have been expected and was therefore not perceived as particularly relevant. Conclusions: The results indicate specific behavioral as well as neural reaction patterns, which can be used especially for an initial subclinical identification of depression.

The ultimatum (UG) and dictator (DG) games are two tasks where a sum of money has to be divided between two players: a proposer and a receiver. Following the rational choice theory, proposers should offer the minimum in the UG and nothing in the DG, due to the presence/absence of the receivers’ bargaining power. The fact that people generally make non-negligible offers in both games has suggested divergent explicative hypotheses and has generated extensive research to examine exogenous and endogenous factors underlying such decisions. Among the contextual factors affecting the proposers’ offers, the sense of entitlement or of ownership has been shown to reduce offers significantly. A frequent way to induce the sense of entitlement/ownership has been to assign the role of proposer to the player who apparently has better scored in skill tasks executed before the UG or DG or has more contributed, through a previous luck game, to the amount to be shared. Such manipulations, however, could produce a possible overlapping between “ownership” and “merit,” that in this study we aimed to disentangle. We manipulated the participants’ initial endowment through a luck game, by increasing, decreasing or leaving it unchanged, to investigate whether winnings or losses by chance influenced offers in UG and DG in similar or different ways depending on their respective features. All participants played as proposers but this role was apparently random and disconnected from the outcomes of the luck game. Furthermore, we investigated whether the putative effect of experimental manipulation was mediated by the changes in emotions elicited by the luck game and/or by the emotions and beliefs related to decision-making. We used a non-economic version of the games, in which tokens were divided instead of money. In the study, 300 unpaid undergraduates (M = 152) from different degree programs, aged between 18 and 42 years, participated. The results revealed that the effect of outcome manipulation on offers was moderated by the specific structure of the UG and DG. Instead, emotional reactions barely mediated the effect of the experimental manipulation, suggesting that their role in those decisions is less relevant than is assumed in the literature.

Bipolar Disorder (BD) has a debilitating impact on psychosocial functioning and social decision-making. Recent evidence using the Ultimatum Game (UG) has shown increased rejection of moderately unfair offers in BD, suggesting impaired processing of ambiguous social information related to fairness. The present study builds upon this finding to investigate the neural substrates of fairness processing in BD. During functional magnetic resonance imaging scanning, euthymic BD patients (n = 41) and matched healthy controls (HC; n = 41) accepted or rejected very unfair, moderately unfair, or fair offers in the UG. Acceptance rates of moderately unfair offers were significantly lower in BD patients. This aberrant behavior co-occurred with abnormal brain responses to moderately unfair offers. Compared to HC, BD patients exhibited hypoactivation of right anterior insula in response to moderately unfair offers suggesting impaired integration of affective and contextual information. BD patients also displayed stronger deactivation of posterior and middle insula in response to moderately unfair offers reflecting impaired processing of the contextual aspects of fairness. The level of impulsivity of BD patients positively correlated with the abnormal deactivation of posterior and middle insula. A separate analysis revealed increased activation of dorsal ACC and left ventrolateral PFC in response to rejected compared to accepted offers in BD patients. Taken together, our findings suggest impaired processing of ambiguous social information in euthymic BD patients which is associated with increased rejection of moderately unfair offers. This impairment may reflect a failure to integrate contextual information and may be related to increased trait impulsivity.

Most communist economies were dominated by large collective farms. Today, smaller family farms often coexist with larger corporate and collective farms in these countries. The roles of other-regarding preferences and social norms have been largely neglected in the debate on farmers' organizational choices. We conducted lab-in-the-field ultimatum game experiments with 397 cotton farmers from collective and family farms. Large and statistically significant differences existed in the rejection behavior among the two farm types. Punishment of unfair behavior explained organizational choice, both with and without controlling for other factors. We conclude that the continuation of dual farm structures requires tailored policy support.

Over the past fifteen years, research has demonstrated the central role of interpersonal emotions in communicating intentions, goals and desires. These emotions can be conveyed through facial expressions during specific social interactions, such as in the context of coordination between economic agents, where information inferred from them can influence certain decision-making processes. We investigated whether four facial expressions (happiness, neutral, angry and disgusted) can affect decision-making in the Ultimatum Game (UG). In this economic game, one player (proposer) plays the first move and proposes how to allocate a given amount of money in an anonymous one-shot interaction. If the other player (responder) accepts the proposal, each player receives the allocated amount of money; if he/she rejects the offer, both players receive nothing. During the task, participants acted as the responder (Experiment 1) or the proposer (Experiment 2) while seeing the opponent’s facial expression. For the responders, the results show that the decision was mainly driven by the fairness of the offer, with a small main effect of emotion. No interaction effect was found between emotion and offer. For the proposers, the results show that participants modulated their offers on the basis of the responders’ expressed emotions. The most generous/fair offers were proposed to happy responders. Less generous/fair offers were proposed to neutral responders. Finally, the least generous/fair offers were proposed to angry and disgusted responders.

This study examines experimental evidence showing how ethics power allocation mechanisms affect an individual’s in-organization resource division and ethical behavior. We used two two-stage lab experiments to explore power seeking and usage; the experiments contained two stages of power contending and power usage. Stage one used two different power-seeking mechanisms in the honesty game. Stage two was based on the dictator game and the ultimatum game to measure an individual’s power usage. The results show that the decisions taken by power-holders could influence the optimization of collective resources, and power-holders who gain power with unethical methods could result in collective resource allocation inequities. With more balanced in-organization power, members tend to be more honest. Subjects also adjust their unethical behavior to adapt to the environment, which could cause the diffusion of unethical behavior. This paper re-designed the dictator game and the ultimatum game by adding an ethically vulnerable power acquisition mechanism. For organizations to prevent the disproportionate dispersion of resources and achieve more public benefits, it is meaningful for managers to create a proper in-organization ethical power allocation mechanism.

Research from cultural and social psychology has identified a central role of self-construal, or the way one views themselves in relation to others, in social cognition. Accordingly, it is plausible that self-construal plays an instrumental role in important aspects of decision-making relating to fairness considerations. Prior research has shown that priming methodology is a useful tool to experimentally isolate the effect of self-construal on social decision-making processes. In the current study we investigated the neural effects of self-construal priming on fairness considerations, using an Ultimatum Game setup (N = 97). Based on previous findings, we predicted an interaction between the self-construal prime and gender on Ultimatum Game behavior; males primed with interdependence would reject the offer relatively more compared to independence, and vice versa for females. As previous neuro-imaging research has established an instrumental role of the anterior insula (AI) and ventromedial prefrontal cortex (vmPFC) in the rejection of unfair offers, we expected higher rejection rates to be mirrored by increased activity in these regions. However, the analyses did not confirm these predictions. As further inspection of the data revealed a habituation effect, we performed a follow-up analysis on the first block (N = 59). This subsequent analysis revealed that priming interdependence resulted in reduced AI activity compared to priming independence, although no behavioral differences were observed. The difference was theorized to result from motivations as conflict avoidance and harmony maintenance, commonly associated with interdependence. Furthermore, the analysis revealed greater vmPFC activity for females compared to males for rejected offers, although this effect was not robust when controlled for trait self-construal. These follow-up analyses suggest that self-construal priming influences insula activity, as well as implicating an underlying role of trait self-construal in observed gender differences in vmPFC activity relating to fairness considerations.

Testosterone plays a key role in shaping human social behavior. Recent findings have linked testosterone to altruistic behavior in economic decision tasks depending on group membership and intergroup competition. The preferential treatment of ingroup members, while aggression and discrimination is directed towards outgroup members, has been referred to as parochial altruism. Here we investigated in two consecutive studies, whether testosterone is associated with parochial altruism depending on individual tendency for costly punishment. In the first study, 61 men performed a single-shot ultimatum game (UG) in a minimal group context, in which they interacted with members of an ingroup and outgroup. In the second study, 34 men performed a single-shot UG in a more realistic group context, in which they responded to the proposals of supporters of six political parties during the German election year 2017. Political parties varied in their social distance to the participants’ favorite party as indicated by an individual ranking. Participants of study 2 also performed a cued recall task, in which they had to decide whether they had already encountered a face during the previous UG (old-new decision). In order to make the UG data of study 2 most comparable to the data of study 1, the rejection rates of several parties were combined according to the social distance ranking they achieved. Parties ranked 1 to 3 formed the relatively close and favored ‘ingroup’ that shared similar political values with the participant (e.g., left wing parties), while the ‘outgroup’ consisted of parties ranked from 4 to 6 with more distant or even antagonistic political views (e.g., conservative to right wing parties). In both studies, results showed a parochial pattern with higher rejection rates made in response to outgroup compared to ingroup offers. Interestingly, across studies higher salivary testosterone was associated with higher rejection rates related to unfair outgroup offers in comparison to the unfair offers made by ingroup members. The present findings suggest that latent intergroup biases during decision-making may be positively related to endogenous testosterone. Similar to previous evidence that already indicated a role of testosterone in shaping male parochial altruism in male soccer fans, these data underscore the general, yet rather subtle role of male testosterone also in other social settings.

Moral elevation is the prototypical emotional response when witnessing virtuous deeds of others. Yet, little is known about the role of individual differences that moderate the susceptibility to experiencing this self-transcendent emotion. The present experiment investigated the role of personality traits as moderators of elevation and its behavioral effects using economic games as a measure for prosocial behavior. One aim was to replicate prior findings on trait Engagement with Moral Beauty as moderator for experimentally induced state elevation. A second aim was to explore new potential moderators that were found to be connected to the moral realm: Honesty-Humility, Agreeableness vs. Anger, and Need for Cognition. Third, the present study is among the few investigating the effects of elevation on different prosocial actions and intentions. A sample of US American college students (N = 144) was randomly assigned to either watch a morally uplifting or a humorous video clip. Afterwards, all participants played a dictator game and an ultimatum game, and were asked to volunteer in another time-consuming experiment. In line with our hypotheses, experimentally induced state elevation promoted prosocial behavior, however, only within the dictator game. Also in line with our hypotheses, higher levels of Need for Cognition and higher levels of Engagement with Moral Beauty (but not higher levels of Honesty-Humility and Agreeableness vs. Anger) increased prosocial behavior within the experimental group. In contrast to our hypotheses, none of the investigated personality traits moderated the proneness to experience the state of elevation after seeing an elevating video clip; only the behavioral consequences of elevation were moderated. Our results replicate and extend prior findings on moderators for elevation and exemplify the importance of investigating the role of personality traits in the context of the moral elevation phenomenon.

In this research, we examine how cooperation emerges and develops in sequential dyadic interactions when the initial interaction varies in strategic considerations (i.e., fear of partner rejection) or potential gossip by one’s partner that may affect subsequent interactions. In a lab experiment involving real-time interactions (N = 240) across 39 sessions, participants acted in different roles (i.e., Person A, B, and C) in two different games—Person A was first assigned to allocate an amount of resource to Person B in a dictator game or an ultimatum game. Afterward, Person C interacted with Person A (i.e., trustee) as a trustor in a trust game. Prior to their decisions, participants (a) learned that Person B could gossip by sending evaluations about Person A’s behavior to Person C prior to the trust game or (b) did not receive this information. Findings replicate previous research showing that potential gossip by one’s partner greatly increases cooperation that is revealed in the resources allocated to the partner. Yet, compared to the dictator game, the presence of strategic considerations in the ultimatum game does not significantly enhance cooperation, and even makes people less likely to reciprocate others’ behavior in the subsequent interaction. Interestingly, when there is no gossip, those who have played the ultimatum game, compared to the dictator game, are more trusted by others but do not vary in reciprocity in the subsequent interaction. However, when there is gossip, those who have played the dictator game, compared to the ultimatum game, are more trusted and also more likely to reciprocate others’ behavior in the subsequent interaction. These findings imply that gossip invariably promotes cooperation across strategic and non-strategic situations, but the potential rejection by one’s partner weakly promotes cooperation, and even undermines future cooperation especially when paired with reputation sharing opportunities. We discuss the implications of these findings for implementing reputation systems that can promote and maintain cooperation cost-effectively.

Human decision-making behaviors in social contexts are largely driven by fairness considerations. The dual-process model suggests that in addition to cognitive processes, emotion contributes to economic decision-making. Although humor, as an effective emotional regulation strategy to induce positive emotion, may influence an individual’s emotional state and decision-making behavior, previous studies have not examined how humor modulates fairness-related responses in the gain and loss contexts simultaneously. This study uses the Ultimatum Game (UG) in gain and loss contexts to explore this issue. The results show, in the gain context, viewing humorous pictures compared to humorless pictures increased acceptance rates and this effect was moderated by the offer size. However, we did not find the same effect in the loss context. These findings indicate that humor’s affection for fairness considerations may depend on the context and provide insight into the finite power of humor in human sociality, cooperation and norm compliance.

Psychological studies have demonstrated that expectations can have substantial effects on choice behavior, although the role of expectations on social decision making in particular has been relatively unexplored. To broaden our knowledge, we examined the role of expectations on decision making when interacting with new game partners and then also in a subsequent interaction with the same partners. To perform this, 38 participants played an Ultimatum Game (UG) in the role of responders and were primed to expect to play with two different groups of proposers, either those that were relatively fair (a tendency to propose an equal split—the high expectation condition) or unfair (with a history of offering unequal splits—the low expectation condition). After playing these 40 UG rounds, they then played 40 Dictator Games (DG) as allocator with the same set of partners. The results showed that expectations affect UG decisions, with a greater proportion of unfair offers rejected from the high as compared to the low expectation group, suggesting that players utilize specific expectations of social interaction as a behavioral reference point. Importantly, this was evident within subjects. Interestingly, we also demonstrated that these expectation effects carried over to the subsequent DG. Participants allocated more money to the recipients of the high expectation group as well to those who made equal offers and, in particular, when the latter were expected to behave unfairly, suggesting that people tend to forgive negative violations and appreciate and reward positive violations. Therefore, both the expectations of others’ behavior and their violations play an important role in subsequent allocation decisions. Together, these two studies extend our knowledge of the role of expectations in social decision making.

Decisional conflicts have been investigated with social decision-making tasks, which represent good models to elicit social and emotional dynamics, including fairness perception. To explore these issues, we created two modified versions of the UG framed within an economic vs. a moral context that included two kinds of unfair offers: advantageous (upside, U) or disadvantageous (downside, D) from the responder’s perspective, and vice-versa for the proponent. The hemodynamic activity of 36 participants, 20 females and 16 males, was continuously recorded with fNIRS to investigate the presence of general or specific circuits between the different experimental conditions. Results showed that disadvantageous offers (D) are associated with an increased widespread cortical activation. Furthermore, we found that advantageous moral choices at the expense of others (U) were related to the activation of the right prefrontal cortex. Finally, we found gender-related differences in brain activations in the different frameworks. In particular, the DLPFC was recruited by females during the economic task, and by males during the moral frame. In conclusion, the present study confirmed and expanded previous data about the role of the prefrontal cortices in decision-making, suggesting the need for further studies to understand better the different prefrontal networks serving moral and economic decisions also considering gender-related differences.

Being treated fairly by others is an important need in everyday life. Experimentally, fairness can be studied using the Ultimatum Game, where the decision to reject a low, but non-zero offer is seen as a way to punish the other player for an unacceptable offer. The canonical explanation of such behavior is inequity aversion: people prefer equal outcomes over personal gains. However, there is abundant evidence that people's decision to reject a low offer can be changed by contextual factors and their emotional state, which cannot be explained by the inequity aversion model. Here, we expand a recent alternative explanation: rejections are driven by deviations from expectations: the larger the difference between the actual offer and the expected offer, the more likely one is to reject the offer. Specifically, we provided participants with explicit information on what kind of offers to expect using histograms depicting distribution of offers given in a previous experiment by the same proposers. Crucially, we showed four different distributions, manipulating both the mean and the variance of these expected sets of offers. We found that 50% of our participants clearly and systematically changed their behavior as a function of their expectations (11% followed the standard-economic model of pure self-interest and 39% where not distinguishable from the inequity-aversion model). Using a logistic mixed-model analysis, we found that the mean and variance differently affect the decision to reject an offer. Specifically, the mean expected offer affected the threshold of what offers are acceptable, while the expected variance of offers changed how strict participants were about this threshold. Together, these results suggest that social expectations have a more complex nature as current theories propose.