Do humans really punish altruistically? A closer look

Confusion cannot explain cooperative behavior in public goods games

Some scholars find that behavioral variation in the public goods game is explained by variations in participants' understanding of how to maximize payoff and that confusion leads to cooperation. Their findings lead them to question the common assumption in behavioral economics experiments that choices reflect motivations. We conduct two experiments, in which we minimize confusion by providing participants with increased training. We also introduce a question that specifically assesses participants' understanding of payoff maximization choices. Our experimental results show that the distribution of behavior types is significantly different when participants play with computers versus humans. A significant increase in contributions is also observed when participants play with humans compared to when they play with computers. Moreover, social norms may be the main motive for contributions when playing with computers. Our findings suggest that social preferences, rather than confusion, play a crucial role in determining contributions in public goods games when playing with humans. We therefore argue that the assumption in behavioral economics experiments that choices reveal motivations is indeed valid.

The science of justice: The neuropsychology of social punishment

The social punishment (SP) of norm violations has received much attention across multiple disciplines. However, current models of SP fail to consider the role of motivational processes, and none can explain the observed behavioral and neuropsychological differences between the two recognized forms of SP: second-party punishment (2PP) and third-party punishment (3PP). After reviewing the literature giving rise to the current models of SP, we propose a unified model of SP which integrates general psychological descriptions of decision-making as a confluence of affect, cognition, and motivation, with evidence that SP is driven by two main factors: the amount of harm (assessed primarily in the salience network) and the norm violator's intention (assessed primarily in the default-mode and central-executive networks). We posit that motivational differences between 2PP and 3PP, articulated in mesocorticolimbic pathways, impact final SP by differentially impacting the assessments of harm and intention done in these domain-general large-scale networks. This new model will lead to a better understanding of SP, which might even improve forensic, procedural, and substantive legal practices.

Norm Dynamics: Interdisciplinary Perspectives on Social Norm Emergence, Persistence, and Change

Social norms are the glue that holds society together, yet our knowledge of them remains heavily intellectually siloed. This article provides an interdisciplinary review of the emerging field of norm dynamics by integrating research across the social sciences through a cultural-evolutionary lens. After reviewing key distinctions in theory and method, we discuss research on norm psychology-the neural and cognitive underpinnings of social norm learning and acquisition. We then overview how norms emerge and spread through intergenerational transmission, social networks, and group-level ecological and historical factors. Next, we discuss multilevel factors that lead norms to persist, change, or erode over time. We also consider cultural mismatches that can arise when a changing environment leads once-beneficial norms to become maladaptive. Finally, we discuss potential future research directions and the implications of norm dynamics for theory and policy.

"Proof Under Reasonable Doubt": Ambiguity of the Norm Violation as Boundary Condition of Third-Party Punishment

In six studies, we consistently observed costly third-party punishment (3PP) to decrease under ambiguity of the norm violation. Our research suggests that, under ambiguity, some people experience concerns about punishing unfairly. Those with higher (vs. lower) other-oriented justice sensitivity (Observer JS) reduced 3PP more pronouncedly (in Studies 1-3 and 4b, but not replicated in Studies 4-5). Moreover, those who decided to resolve the ambiguity (hence, removing the risk of punishing unfairly) exceeded the 3PP observed under no ambiguity (Study 4). However, we did not consistently observe these concerns about punishing unfairly to affect 3PP (Studies 4-5). We further considered whether people could use ambiguity as justification for remaining passive-thus, avoiding the costs of 3PP. We did not find conclusive evidence supporting this notion. Taken together, ambiguity entails a situational boundary of 3PP that sheds light on the prevalence of this behavior and, potentially, on its preceding decision-making.

Self-interested learning is more important than fair-minded conditional cooperation in public-goods games

Why does human cooperation often unravel in economic experiments despite a promising start? Previous studies have interpreted the decline as the reaction of disappointed altruists retaliating in response to non-altruists (Conditional Cooperators hypothesis). This interpretation has been considered evidence of a uniquely human form of cooperation, motivated by an altruistic concern for equality ('fairness') and requiring special evolutionary explanations. However, experiments have typically shown individuals not only information about the decisions of their groupmates (social information) but also information about their own payoffs. Showing both confounds explanations based on conditional cooperation with explanations based on confused individuals learning how to better play the game (Confused Learners hypothesis). Here we experimentally decouple these two forms of information, and thus these two hypotheses, in a repeated public-goods game. Analysing 616 Swiss university participants, we find that payoff information leads to a greater decline, supporting the Confused Learners hypothesis. In contrast, social information has a small or negligible effect, contradicting the Conditional Cooperators hypothesis. We also find widespread evidence of both confusion and selfish motives, suggesting that human cooperation is maybe not so unique after all.

Optimizing the social utility of judicial punishment: An evolutionary biology and neuroscience perspective

Punishment as a response to impairment of individual or group welfare may be found not only among humans but also among a wide range of social animals. In some cases, acts of punishment serve to increase social cooperation among conspecifics. Such phenomena motivate the search for the biological foundations of punishment among humans. Of special interest are cases of pro-social punishment of individuals harming others. Behavioral studies have shown that in economic games people punish exploiters even at a cost to their own welfare. Additionally, neuroimaging studies have reported activity during the planning of such punishment in brain areas involved in the anticipation of reward. Such findings hint that there is an evolutionarily honed basic drive to punish social offenders. I argue that the transfer of punishment authority from the individual to the group requires that social offenders be punished as a public good, even if such punishment is not effective as retribution or deterrent. Furthermore, the social need for punishment of offenders has implications for alternatives to incarceration, publicity of punishment, and judicial structure.

On second thought … the influence of a second stage in the ultimatum game on decision behavior, electro-cortical correlates and their trait interrelation

Previous EEG research only investigated one stage ultimatum games (UGs). We investigated the influence of a second bargaining stage in an UG concerning behavioral responses, electro-cortical correlates and their moderations by the traits altruism, anger, anxiety, and greed in 92 participants. We found that an additional stage led to more rejection in the 2-stage UG (2SUG) and that increasing offers in the second stage compared to the first stage led to more acceptance. The FRN during a trial was linked to expectance evaluation concerning the fairness of the offers, while midfrontal theta was a marker for the needed cognitive control to overcome the respective default behavioral pattern. The FRN responses to unfair offers were more negative for either low or high altruism in the UG, while high trait anxiety led to more negative FRN responses in the first stage of 2SUG, indicating higher sensitivity to unfairness. Accordingly, the mean FRN response, representing the trait-like general electrocortical reactivity to unfairness, predicted rejection in the first stage of 2SUG. Additionally, we found that high trait anger led to more rejections for unfair offer in 2SUG in general, while trait altruism led to more rejection of unimproving unfair offers in the second stage of 2SUG. In contrast, trait anxiety led to more acceptance in the second stage of 2SUG, while trait greed even led to more acceptance if the offer was worse than in the stage before. These findings suggest, that 2SUG creates a trait activation situation compared to the UG.

Decoupling cooperation and punishment in humans shows that punishment is not an altruistic trait

Economic experiments have suggested that cooperative humans will altruistically match local levels of cooperation (conditional cooperation) and pay to punish non-cooperators (altruistic punishment). Evolutionary models have suggested that if altruists punish non-altruists this could favour the evolution of costly helping behaviours (cooperation) among strangers. An often-key requirement is that helping behaviours and punishing behaviours form one single conjoined trait (strong reciprocity). Previous economics experiments have provided support for the hypothesis that punishment and cooperation form one conjoined, altruistically motivated, trait. However, such a conjoined trait may be evolutionarily unstable, and previous experiments have confounded a fear of being punished with being surrounded by cooperators, two factors that could favour cooperation. Here, we experimentally decouple the fear of punishment from a cooperative environment and allow cooperation and punishment behaviour to freely separate (420 participants). We show, that if a minority of individuals is made immune to punishment, they (i) learn to stop cooperating on average despite being surrounded by high levels of cooperation, contradicting the idea of conditional cooperation and (ii) often continue to punish, 'hypocritically', showing that cooperation and punishment do not form one, altruistically motivated, linked trait.

Intrinsic functional connectivity of the frontoparietal network predicts inter-individual differences in the propensity for costly third-party punishment

Humans are motivated to give norm violators their just deserts through costly punishment even as unaffected third parties (i.e., third-party punishment, TPP). A great deal of individual variability exists in costly punishment; however, how this variability particularly in TPP is represented by the brain's intrinsic network architecture remains elusive. Here, we examined whether inter-individual differences in the propensity for TPP can be predicted based on resting-state functional connectivity (RSFC) combining an economic TPP game with task-free functional neuroimaging and a multivariate prediction framework. Our behavioral results revealed that TPP punishment increased with the severity of unfairness for offers. People with higher TPP propensity punished more harshly across norm-violating scenarios. Our neuroimaging findings showed RSFC within the frontoparietal network predicted individual differences in TPP propensity. Our findings contribute to understanding the neural fingerprint for an individual's propensity to costly punish strangers, and shed some light on how social norm enforcement behaviors are represented by the brain's intrinsic network architecture.

Looking Like a Million Dollars: Does Attractiveness Priming Increase Altruistic Behavior in Experimental Games?

The emergence of altruistic behavior constitutes one of the most widely studied problems in evolutionary biology and behavioral science. Multiple explanations have been proposed, most importantly including kin selection, reciprocity, and costly signaling in sexual selection. In order to test the latter, this study investigated whether people behave more altruistically when primed by photographs of attractive faces and whether more or less altruistic people differ in the number of sexual and romantic partners. Participants in the general population (N = 158, 84 F, 74 M) first rated the attractiveness of photographs of 20 faces of the opposite (sexually preferred) sex and then played the Dictator and Ultimatum Games (DG and UG). The photograph rating acted as priming; half the participants received photographs of people rated as more attractive than average in an earlier study, and the other half received photographs previously rated as less attractive. The attractiveness-primed participants, especially men, were expected to behave more altruistically-signaling that they are desirable, resource-possessing partners. We also expected altruists to self-report more sexual and romantic partners. The observed difference between altruistic behaviors in the attractiveness- and unattractiveness-primed groups occurred in UG offers, however, in the opposite than expected direction in women. The number of sexual partners was positively correlated to minimum acceptable offers (MAOs) in the UG, in line with expectations based on the theory of costly signaling.

Experimental evidence that apologies promote forgiveness by communicating relationship value

Robust evidence supports the importance of apologies for promoting forgiveness. Yet less is known about how apologies exert their effects. Here, we focus on their potential to promote forgiveness by way of increasing perceptions of relationship value. We used a method for directly testing these causal claims by manipulating both the independent variable and the proposed mediator. Namely, we use a 2 (Apology: yes vs. no) × 2 (Value: high vs. low) concurrent double-randomization design to test whether apologies cause forgiveness by affecting the same causal pathway as relationship value. In addition to supporting this causal claim, we also find that apologies had weaker effects on forgiveness when received from high-value transgressors, suggesting that the forgiveness-relevant information provided by apologies is redundant with relationship value. Taken together, these findings from a rigorous methodological paradigm help us parse out how apologies promote relationship repair.

Toddlers' interventions toward fair and unfair individuals

Cooperative societies rely on reward and punishment for norm enforcement. We examined the developmental origin of these interventions in the context of distributive fairness: past research has shown that infants expect resources to be distributed fairly, prefer to interact with fair distributors, and evaluate others based on their fair and unfair resource allocations. In order to determine whether infants would intervene in third-party resource distributions by use of reward and punishment we developed a novel task. Sixteen-month-old infants were taught that one side of a touch screen produces reward (vocal statements expressing praise; giving a cookie), whereas the other side produces punishment when touched (vocal statements expressing admonishment; taking away a cookie). After watching videos in which one actor distributed resources fairly and another actor distributed resources unfairly, participants' screen touches on the reward and punishment panels while the fair and unfair distributors appeared on screen were recorded. Infants touched the reward side significantly more than the punishment side when presented with the fair distributor but touched the screen sides equally when the unfair distributor was shown. Control experiments revealed no evidence of reward or punishment when infants saw food items they liked and disliked, or individuals uninvolved in the resource distribution events. These results provide the earliest evidence that infants are able to spontaneously intervene in socio-moral situations by rewarding positive actions.

Egoistic punishment outcompetes altruistic punishment in the spatial public goods game

The evolution of costly punishment is a puzzle due to cooperators’ second-order free-riding. Previous studies have proposed many solutions mainly focused on reducing the punishment cost or punishing second-order free riders directly or indirectly. We attempt to explain this confusion from the perspective of punishment motivation, which is why the punisher is willing to pay the cost. The answer is that the punisher is egoistic. Egoistic punishment aims to protect punishers’ own cooperative benefits shared by the defectors. In such case, egoistic punishers would pay a cost in punishing defectors and retrieve lost payoffs from defectors. Here, we examined the evolution and performance of egoistic punishment and compared it with typical altruistic punishment using classic peer-punishment and pool-punishment modes. Results showed egoistic punishment can evolve and effectively promote cooperation within a large parameter range, whether in a well-mixed or structured population, or through peer-punishment or pool-punishment modes. This result is also robust to different strategy-updating rules. The evolution under the pool-punishment mechanism is more complicated. The influence of parameters is counter-intuitive because of cycle dominance; namely, the cost is the key factor to control the level of cooperation and the fine determines the ratio of the punishers and cooperators. Compared with altruistic punishment, egoistic punishment can promote cooperation in a lower-fine and higher-cost area, especially in the pool punishment mode, and the egoistic punishers have stronger survivability. Egoistic punishers represent the natural fairness in a social system. Results revealed that focusing on individual equity can significantly promote collective cooperation. This study provides another explanation for the evolution of costly punishment.

Moral Judgments

Research on morality has increased rapidly over the past 10 years. At the center of this research are moral judgments-evaluative judgments that a perceiver makes in response to a moral norm violation. But there is substantial diversity in what has been called moral judgment. This article offers a framework that distinguishes, theoretically and empirically, four classes of moral judgment: evaluations, norm judgments, moral wrongness judgments, and blame judgments. These judgments differ in their typical objects, the information they process, their speed, and their social functions. The framework presented here organizes the extensive literature and provides fresh perspectives on measurement, the nature of moral intuitions, the status of moral dumbfounding, and the prospects of dual-process models of moral judgment. It also identifies omitted questions and sets the stage for a broader theory of moral judgment, which the coming decades may bring forth.

Distinct affective responses to second- and third-party norm violations

Social norm violations provoke strong emotional reactions that often culminate in punishment of the wrongdoer. This is true not only when we are the victims of the norm violation (second-party), but also when witnessing a complete stranger being victimized (third-party). What remains unclear, however, is whether second- and third-party punishments are associated with different emotions. To address this question, here we examine how subjects respond affectively to both second- and third-party norm violations in an economic game. Our results indicate that while second- and third-parties respond to norm violations by punishing wrongdoers similarly, they report experiencing distinct emotional states as a result of the violation. Specifically, we observed a cross-over interaction between anger and moral outrage depending on the party's context: while anger was more frequently reported for second- than for third-party violations, moral outrage was more evoked by third-party than second-party violations. Disgust and sadness were the most prevalently reported emotions, but their prevalence were unaffected by party contexts. These results indicate that while responses to second- and third-party violations result in similar punishment, they are associated with the expression of distinct affective palettes. Further, our results provide additional evidence that moral outrage is a critical experience in the evaluation of third-party wrongdoings.

Sentiment Analysis in Children with Neurodevelopmental Disorders in an Ingroup/Outgroup Setting

People punish transgressors with different intensity depending if they are members of their group or not. We explore this in a cross-sectional analytical study with paired samples in children with developmental disorders who watched two videos and expressed their opinion. In Video-1, a football-player from the participant's country scores a goal with his hand. In Video-2, a player from another country does the same against the country of the participant. Each subject watched the two videos and their answers were compared. The autism spectrum disorder (ASD) group showed negative feelings in Video 1 (M = - .1; CI 95% - .51 to .31); and in Video 2 (M = - .43; CI 95% .77 to - .09; t(8) = 1.64, p = .13), but the attention deficit hyperactivity disorder, learning disabilities, intellectual disability groups showed positive opinion in Video-1 and negative in Video-2. This suggests that children with ASD respect rules regardless of whether those who break them belong or not to their own group, possibly due to lower degrees of empathy.

It's costly punishment, not altruistic: Low midfrontal theta and state anger predict punishment

Punishment in economic games has been interpreted as "altruistic." However, it was shown that punishment is related to trait anger instead of trait altruism in a third-party dictator game if compensation is also available. Here, we investigated the influence of state anger on punishment and compensation in the third-party dictator game. Therefore, we used movie sequences for emotional priming, including the target states anger, happy, and neutral. We measured the Feedback-Related Negativity (FRN) and midfrontal theta band activation, to investigate an electro-cortical correlate of the processing of fair and unfair offers. Also, we assessed single-trial FRN and midfrontal theta band activation as a predictor for punishment and compensation. We found that punishment was linked to state anger. Midfrontal theta band activation, which has previously been linked to altruistic acts and cognitive control, predicted less punishment. Additionally, trait anger led to enhanced FRN for unfair offers. This led to the interpretation that the FRN depicts the evaluation of fairness, while midfrontal theta band activation captures an aspect of cognitive control and altruistic motivation. We conclude that we need to redefine "altruistic punishment" into "costly punishment," as no direct link of altruism and punishment is given. Additionally, midfrontal theta band activation complements the FRN and offers additional insights into complex responses and decision processes, especially as a single trial predictor.

When and Why Do Third Parties Punish Outside of the Lab? A Cross-Cultural Recall Study

Punishment can reform uncooperative behavior and hence could have contributed to humans’ ability to live in large-scale societies. Punishment by unaffected third parties has received extensive scientific scrutiny because third parties punish transgressors in laboratory experiments on behalf of strangers that they will never interact with again. Often overlooked in this research are interactions involving people who are not strangers, which constitute many interactions beyond the laboratory. Across three samples in two countries (United States and Japan; N = 1,294), we found that third parties’ anger at transgressors, and their intervention and punishment on behalf of victims, varied in real-life conflicts as a function of how much third parties valued the welfare of the disputants. Punishment was rare (1–2%) when third parties did not value the welfare of the victim, suggesting that previous economic game results have overestimated third parties’ willingness to punish transgressors on behalf of strangers.

Punishment: one tool, many uses

Humans are outstanding in their ability to cooperate with unrelated individuals, and punishment - paying a cost to harm others - is thought to be a key supporting mechanism. According to this view, cooperators punish defectors, who respond by behaving more cooperatively in future interactions. However, a synthesis of the evidence from laboratory and real-world settings casts serious doubts on the assumption that the sole function of punishment is to convert cheating individuals into cooperators. Instead, punishment often prompts retaliation and punishment decisions frequently stem from competitive, rather than deterrent motives. Punishment decisions often reflect the desire to equalise or elevate payoffs relative to targets, rather than the desire to enact revenge for harm received or to deter cheats from reoffending in future. We therefore suggest that punishment also serves a competitive function, where what looks like spiteful behaviour actually allows punishers to equalise or elevate their own payoffs and/or status relative to targets independently of any change in the target's behaviour. Institutions that reduce or remove the possibility that punishers are motivated by relative payoff or status concerns might offer a way to harness these competitive motives and render punishment more effective at restoring cooperation.

Neurocognitive mechanisms of reactions to second- and third-party justice violations

The aim of the current study was threefold: (i) understand people's willingness to engage in either punishment of the perpetrator or compensation of the victim in order to counteract injustice; (ii) look into the differences between victims of and witnesses to injustice; (iii) investigate the different role played by social preference and affective experience in determining these choices. The sample tested here showed an equal preference for punishment and compensation; neuroimaging findings suggested that compensation, as opposed to punishment, was related to Theory of Mind. Partially supporting previous literature, choosing how to react to an injustice as victims, rather than witnesses, triggered a stronger affective response (striatal and prefrontal activation). Moreover, results supported the idea that deciding whether or not to react to an injustice and then how severely to react are two distinct decisional stages underpinned by different neurocognitive mechanisms, i.e., sensitivity to unfairness (anterior insula) and negative affectivity (amygdala). These findings provide a fine-grained description of the psychological mechanisms underlying important aspects of social norm compliance.

Sex Affects the Relationship Between Third Party Punishment and Cooperation

Prosocial third-party punishment (3PP) is a punitive behavior against antisocial individuals, which might explain extended cooperativeness in humans. 3PP shows sexual dimorphism, being more frequent in men than in women. We studied whether sexually dimorphic features related to sexual hormones during development (facial dimorphism and 2D:4D) influence the tendency to engage in 3PP in a sample of 511 women and 328 men. After playing a Prisoner's Dilemma, participants had to decide whether to penalize the defection of a third player who had exploited his/her counterpart's cooperation. In line with previous studies, we observe that men are more prone to engage in 3PP than women. We find that this sex difference is due to cooperative men being more likely to punish than cooperative women. In addition, men with higher facial masculinity are less likely to engage in 3PP, whereas no features influence 3PP in women. We discuss the possibility that sex differences in the motivations and fitness implications underlying 3PP might be driving the observed results.

Altruistic punishment is connected to trait anger, not trait altruism, if compensation is available

Altruistic punishment and altruistic compensation are important concepts that are used to investigate altruism. However, altruistic punishment has been found to be correlated with anger. We were interested whether altruistic punishment and altruistic compensation are both driven by trait altruism and trait anger or whether the influence of those two traits is more specific to one of the behavioral options. We found that if the participants were able to apply altruistic compensation and altruistic punishment together in one paradigm, trait anger only predicts altruistic punishment and trait altruism only predicts altruistic compensation. Interestingly, these relations are disguised in classical altruistic punishment and altruistic compensation paradigms where participants can either only punish or compensate. Hence altruistic punishment and altruistic compensation paradigms should be merged together if one is interested in trait altruism without the confounding influence of trait anger.

An exploration of third parties' preference for compensation over punishment: six experimental demonstrations

Research suggests that to restore equity, third parties prefer compensation of a victim over the punishment of a perpetrator. It remains unclear, however, whether this preference for compensation is stable or specific to certain situations. In six experimental studies, we find that adjustments in the characteristics of the situation or in the available behavioral options hardly modify the preference of compensation over punishment. This preference for compensation was found even in cases where punishment might refrain a perpetrator from acting unfairly again in the future, and even when punishment has a greater impact in restoring equity than compensation does. Thus, the preference of compensation over punishment appears to be quite robust. Implications and ideas for future research are discussed.

Neurobiological Mechanisms of Responding to Injustice

People are particularly sensitive to injustice. Accordingly, deeper knowledge regarding the processes that underlie the perception of injustice, and the subsequent decisions to either punish transgressors or compensate victims, is of important social value. By combining a novel decision-making paradigm with functional neuroimaging, we identified specific brain networks that are involved with both the perception of, and response to, social injustice, with reward-related regions preferentially involved in punishment compared with compensation. Developing a computational model of punishment allowed for disentangling the neural mechanisms and psychological motives underlying decisions of whether to punish and, subsequently, of how severely to punish. Results show that the neural mechanisms underlying punishment differ depending on whether one is directly affected by the injustice, or whether one is a third-party observer of a violation occurring to another. Specifically, the anterior insula was involved in decisions to punish following harm, whereas, in third-party scenarios, we found amygdala activity associated with punishment severity. Additionally, we used a pharmacological intervention using oxytocin, and found that oxytocin influenced participants' fairness expectations, and in particular enhanced the frequency of low punishments. Together, these results not only provide more insight into the fundamental brain mechanisms underlying punishment and compensation, but also illustrate the importance of taking an explorative, multimethod approach when unraveling the complex components of everyday decision-making.SIGNIFICANCE STATEMENT The perception of injustice is a fundamental precursor to many disagreements, from small struggles at the dinner table to wasteful conflict between cultures and countries. Despite its clear importance, relatively little is known about how the brain processes these violations. Taking an interdisciplinary approach, we combine methods from neuroscience, psychology, and economics to explore the neurobiological mechanisms involved in both the perception of injustice as well as the punishment and compensation decisions that follow. Using a novel behavioral paradigm, we identified specific brain networks, developed a computational model of punishment, and found that administrating the neuropeptide oxytocin increases the administration of low punishments of norm violations in particular. Results provide valuable insights into the fundamental neurobiological mechanisms underlying social injustice.

The Development of Altruism with Special Reference to Human Relationships: A 10-Stage Theory

All human relationships involve some form of cost and benefit and altruism forms the foundation upon which human relationships are built. In this paper, a taxonomy of human relationships in terms of altruism was constructed. In the proposed taxonomy, human relationships are categorized into three major groups: primary group, secondary group, and tertiary group. The primary group consists of members that are very closely related to each other either by genetic relatedness (e.g., parents, siblings, and cousins) or social relatedness (e.g., mate and close friends) or both. The secondary group consists of members that are socially related but also less closely related with each other (e.g., people of the same political or religious group, teachers, mentors, acquaintances, neighbors, working colleagues, and strangers). Lastly, the tertiary group consists of members of other species. A 10-stage theory of altruism with special reference to human relationships is proposed. The affective, cognitive, and relationship aspects of each stage are delineated in details. There are two developmental principles of altruism. The first principle states that the development of altruism follows the 10-stage theory and moves from Stage 1: Egoism toward the higher stages of altruism slowly. The second developmental principle states that the taxonomy of human relationships is valid at any stage of altruism development. In other words, people at any stage of altruism are more altruistic toward their kin and mate, and then close friends, extended family members, and so on. They are least altruistic toward enemies and members of non-human species. In summary, the proposed developmental principle of altruism and human relationships is logical and robust. It is formulated based on the major developmental and social psychological theories. The theory has the potential in providing a useful framework for future studies on the development and evolution of human relationships.

Support for redistribution is shaped by compassion, envy, and self-interest, but not a taste for fairness

Why do people support economic redistribution? Hypotheses include inequity aversion, a moral sense that inequality is intrinsically unfair, and cultural explanations such as exposure to and assimilation of culturally transmitted ideologies. However, humans have been interacting with worse-off and better-off individuals over evolutionary time, and our motivational systems may have been naturally selected to navigate the opportunities and challenges posed by such recurrent interactions. We hypothesize that modern redistribution is perceived as an ancestral scene involving three notional players: the needy other, the better-off other, and the actor herself. We explore how three motivational systems-compassion, self-interest, and envy-guide responses to the needy other and the better-off other, and how they pattern responses to redistribution. Data from the United States, the United Kingdom, India, and Israel support this model. Endorsement of redistribution is independently predicted by dispositional compassion, dispositional envy, and the expectation of personal gain from redistribution. By contrast, a taste for fairness, in the sense of (i) universality in the application of laws and standards, or (ii) low variance in group-level payoffs, fails to predict attitudes about redistribution.

Who Punishes? The Status of the Punishers Affects the Perceived Success of, and Indirect Benefits From, “Moralistic” Punishment

“Moralistic” punishment of free riders can provide a beneficial reputation, but the immediate behavior is costly to the punisher. In Study 1, we investigated whether variation in status would be perceived to offset or mitigate the costs of punishment. One hundred and nineteen participants were presented with a vignette describing a punishment scenario. Participants predicted whether punishment would occur, how successful it would be, and indicated their attitude to the punisher. Participants believed only intervention by a high-status (HS) individual would be successful and that low-status (LS) individuals would not intervene at all. HS individuals predicted to punish successfully were seen as more formidable and likable. Study 2 investigated whether punishment was necessary to maintain an HS position. One hundred and seventeen participants were presented with a vignette describing a punishment scenario. Participants were asked to indicate whether they wished to be led by the punisher. HS individuals who did not punish were less likely to be chosen as leaders compared to HS punishers, whereas LS individuals who punished were no more or less likely to be chosen than nonpunishers. The results of both studies suggest that only HS individuals are expected to punish, likely because such a position offsets some of the costs of punishment. As a result, only HS individual can access the reputation benefits from punishment. Furthermore, an HS position may be dependent on the willingness to punish antisocial behavior. The ramifications that these results may have for the evolution of moralistic punishment are discussed.

Looking Under the Hood of Third-Party Punishment Reveals Design for Personal Benefit

Third-party intervention, such as when a crowd stops a mugger, is common. Yet it seems irrational because it has real costs but may provide no personal benefits. In a laboratory analogue, the third-party-punishment game, third parties (“punishers”) will often spend real money to anonymously punish bad behavior directed at other people. A common explanation is that third-party punishment exists to maintain a cooperative society. We tested a different explanation: Third-party punishment results from a deterrence psychology for defending personal interests. Because humans evolved in small-scale, face-to-face social worlds, the mind infers that mistreatment of a third party predicts later mistreatment of oneself. We showed that when punishers do not have information about how they personally will be treated, they infer that mistreatment of other people predicts mistreatment of themselves, and these inferences predict punishment. But when information about personal mistreatment is available, it drives punishment. This suggests that humans’ punitive psychology evolved to defend personal interests.

Conditional cooperation and confusion in public-goods experiments

Economic experiments are often used to study if humans altruistically value the welfare of others. A canonical result from public-good games is that humans vary in how they value the welfare of others, dividing into fair-minded conditional cooperators, who match the cooperation of others, and selfish noncooperators. However, an alternative explanation for the data are that individuals vary in their understanding of how to maximize income, with misunderstanding leading to the appearance of cooperation. We show that (i) individuals divide into the same behavioral types when playing with computers, whom they cannot be concerned with the welfare of; (ii) behavior across games with computers and humans is correlated and can be explained by variation in understanding of how to maximize income; (iii) misunderstanding correlates with higher levels of cooperation; and (iv) standard control questions do not guarantee understanding. These results cast doubt on certain experimental methods and demonstrate that a common assumption in behavioral economics experiments, that choices reveal motivations, will not necessarily hold.

Human cooperation shows the distinctive signatures of adaptations to small-scale social life

The properties of individual carbon atoms allow them to chain into complex molecules of immense length. They are not limited to structures involving only a few atoms. The design features of our evolved neural adaptations appear similarly extensible. Individuals with forager brains can link themselves together into unprecedentedly large cooperative structures without the need for large group-beneficial modifications to evolved human design. Roles need only be intelligible to our social program logic, and judged better than alternatives.

Does dishonesty really invite third-party punishment? Results of a more stringent test

Many experiments have demonstrated that people are willing to incur cost to punish norm violators even when they are not directly harmed by the violation. Such altruistic third-party punishment is often considered an evolutionary underpinning of large-scale human cooperation. However, some scholars argue that previously demonstrated altruistic third-party punishment against fairness-norm violations may be an experimental artefact. For example, envy-driven retaliatory behaviour (i.e. spite) towards better-off unfair game players may be misidentified as altruistic punishment. Indeed, a recent experiment demonstrated that participants ceased to inflict third-party punishment against an unfair player once a series of key methodological problems were systematically controlled for. Noticing that a previous finding regarding apparently altruistic third-party punishment against honesty-norm violations may have been subject to methodological issues, we used a different and what we consider to be a more sound design to evaluate these findings. Third-party punishment against dishonest players withstood this more stringent test.

Can centralized sanctioning promote trust in social dilemmas? A two-level trust game with incomplete information

The problem of trust is a paradigmatic social dilemma. Previous literature has paid much academic attention on effects of peer punishment and altruistic third-party punishment on trust and human cooperation in dyadic interactions. However, the effects of centralized sanctioning institutions on decentralized reciprocity in hierarchical interactions remain to be further explored. This paper presents a formal two-level trust game with incomplete information which adds an authority as a strategic purposive actor into the traditional trust game. This model allows scholars to examine the problem of trust in more complex game theoretic configurations. The analysis demonstrates how the centralized institutions might change the dynamics of reciprocity between the trustor and the trustee. Findings suggest that the sequential equilibria of the newly proposed two-level model simultaneously include the risk of placing trust for the trustor and the temptation of short-term defection for the trustee. Moreover, they have shown that even a slight uncertainty about the type of the newly introduced authority might facilitate the establishment of trust and reciprocity in social dilemmas.

Third-party punishers are rewarded, but third-party helpers even more so

Punishers can benefit from a tough reputation, where future partners cooperate because they fear repercussions. Alternatively, punishers might receive help from bystanders if their act is perceived as just and other-regarding. Third-party punishment of selfish individuals arguably fits these conditions, but it is not known whether third-party punishers are rewarded for their investments. Here, we show that third-party punishers are indeed rewarded by uninvolved bystanders. Third parties were presented with the outcome of a dictator game in which the dictator was either selfish or fair and were allocated to one of three treatments in which they could choose to do nothing or (1) punish the dictator, (2) help the receiver, or (3) choose between punishment and helping, respectively. A fourth player (bystander) then sees the third-party's decision and could choose to reward the third party or not. Third parties that punished selfish dictators were more likely to be rewarded by bystanders than third parties that took no action in response to a selfish dictator. However, helpful third parties were rewarded even more than third-party punishers. These results suggest that punishment could in principle evolve via indirect reciprocity, but also provide insights into why individuals typically prefer to invest in positive actions.

Low social status decreases the neural salience of unfairness

Social hierarchy exists in almost all social species and affects everything from resource allocation to the development of intelligence. Previous studies showed that status within a social hierarchy influences the perceived fairness of income allocation. However, the effect of one’s social status on economic decisions is far from clear, as are the neural processes underlying these decisions. In this study, we dynamically manipulated participants’ social status and analyzed their behavior as recipients in the ultimatum game (UG), during which event-related potentials (ERPs) were recorded. Behavioral results showed that acceptance rates for offers increased with the fairness level of offers. Importantly, participants were less likely to accept unfair offers when they were endowed with high status than with low status. In addition, cues indicating low status elicited a more positive P2 than cues indicating high status in an earlier time window (170–240 ms), and cues indicating high status elicited a more negative N400 than cues indicating low status in a later time window (350–520 ms). During the actual reception of offers, the late positivity potential (LPP, 400–700 ms) for unfair offers was more positive in the high status condition than in the low status condition, suggesting a decreased arousal for unfair offers during low status. These findings suggest a strong role of social status in modulating individual behavioral and neural responses to fairness.

Both loved and feared: third party punishers are viewed as formidable and likeable, but these reputational benefits may only be open to dominant individuals

Third party punishment can be evolutionarily stable if there is heterogeneity in the cost of punishment or if punishers receive a reputational benefit from their actions. A dominant position might allow some individuals to punish at a lower cost than others and by doing so access these reputational benefits. Three vignette-based studies measured participants' judgements of a third party punisher in comparison to those exhibiting other aggressive/dominant behaviours (Study 1), when there was variation in the success of punishment (Study 2), and variation in the status of the punisher and the type of punishment used (Study 3). Third party punishers were judged to be more likeable than (but equally dominant as) those who engaged in other types of dominant behaviour (Study 1), were judged to be equally likeable and dominant whether their intervention succeeded or failed (Study 2), and participants believed that only a dominant punisher could intervene successfully (regardless of whether punishment was violent or non-violent) and that subordinate punishers would face a higher risk of retaliation (Study 3). The results suggest that dominance can dramatically reduce the cost of punishment, and that while individuals can gain a great deal of reputational benefit from engaging in third party punishment, these benefits are only open to dominant individuals. Taking the status of punishers into account may therefore help explain the evolution of third party punishment.