Humans display a ‘cooperative phenotype’ that is domain general and temporally stable

Age differences in prosociality across the adult lifespan: A meta-analysis

Lifespan developmental theories and research suggest a positive effect of adult age on prosociality. However, this effect lacks consistency, with many studies excluding the period of midlife. This study summarized cross-sectional studies on adult age and prosociality, combining 120 (independent) samples (n = 103,829) in a lifespan meta-analysis approach. Linear and quadratic age effects on prosociality were analyzed, as well as comparisons between younger, middle-aged, and older adults. Prosociality was assessed via behavioral measures and self-reports. In both these domains, results indicated small linear age effects and higher prosociality in older compared to younger adults, supporting the hypothesis of increased prosociality in older age. Additionally, leveraging open data sets (64/120 independent samples), predominantly unpublished, we found some evidence for potential quadratic age effects on behavioral prosociality: Middle-aged adults exhibited higher behavioral and self-reported prosociality than younger adults, but no differences between middle-aged and older adults were observed. This meta-analysis offers new perspectives on age trajectories of prosociality, suggesting midlife as a potentially important phase of pronounced prosociality.

The role of facial cues in signalling cooperativeness is limited and nuanced

Humans display a remarkable tendency to cooperate with strangers; however, identifying prospective cooperation partners accurately before entering any new relationship is essential to mitigate the risk of being exploited. Visual appearance, as inferrable, for example, from facial images on job portals and dating sites, may serve as a potential signal of cooperativeness. This experimental study examines whether static images enable the correct detection of an individual's propensity to cooperate. Participants first played the Prisoner's Dilemma (PD) game, a standard cooperation task. Subsequently, they were asked to predict the cooperativeness of participants from a prior PD study relying solely on their static facial photographs. While our main results indicate only marginal accuracy improvements over random guessing, a more detailed analysis reveals that participants were more successful at identifying cooperative tendencies similar to their own. Despite no detectable main effect in our primary treatment variations (time pressure versus time delay), participants exhibited increased accuracy in identifying male cooperators under time pressure. These findings point towards a limited yet nuanced role of static facial images in predicting cooperativeness, advancing our understanding of non-behavioral cues in cooperative interactions.

Testing the convergent validity, domain generality, and temporal stability of selected measures of people's tendency to explore

Given the ubiquity of exploration in everyday life, researchers from many disciplines have developed methods to measure exploratory behaviour. There are therefore many ways to quantify and measure exploration. However, it remains unclear whether the different measures (i) have convergent validity relative to one another, (ii) capture a domain general tendency, and (iii) capture a tendency that is stable across time. In a sample of 678 participants, we found very little evidence of convergent validity for the behavioural measures (Hypothesis 1); most of the behavioural measures lacked sufficient convergent validity with one another or with the self-reports. In psychometric modelling analyses, we could not identify a good fitting model with an assumed general tendency to explore (Hypothesis 2); the best fitting model suggested that the different behavioural measures capture behaviours that are specific to the tasks. In a subsample of 254 participants who completed the study a second time, we found that the measures had stability across an 1 month timespan (Hypothesis 3). Therefore, although there were stable individual differences in how people approached each task across time, there was no generalizability across tasks, and drawing broad conclusions about exploratory behaviour from studies using these tasks may be problematic. The Stage 1 protocol for this Registered Report was accepted in principle on 2nd December 2022 https://doi.org/10.6084/m9.figshare.21717407.v1 . The protocol, as accepted by the journal, can be found at https://doi.org/10.17605/OSF.IO/64QJU .

Social identification and paranoia

Paranoia is associated with variation in social behaviour, such as lower inclination to trust others or to behave generously in economic game settings. Such variation may stem, in part, from a reduced tendency to socially identify with others, although previous studies have reported mixed results. We tested whether paranoia involves altered social identification in a pre-registered online study investigating the relationship between a measure of social identification, paranoia, and social behaviours in economic games. We successfully manipulated social identification, but paranoia was associated with slightly increased social identification overall. Neither paranoia nor social identification predicted behaviour in the economic games, and there was no interaction between paranoia and social identification regarding trusting and cooperative behaviours. Our results converge with recent work suggesting that more paranoid individuals may harbour a higher tendency to perceive themselves as having similar beliefs to others. We discuss some key areas for future research to progress understanding in this area.

Human Prosocial Preferences Are Related to Slow-Wave Activity in Sleep

Prosocial behavior is crucial for the smooth functioning of the society. Yet, individuals differ vastly in the propensity to behave prosocially. Here, we try to explain these individual differences under normal sleep conditions without any experimental modulation of sleep. Using a portable high-density EEG, we measured the sleep data in 54 healthy adults (28 females) during a normal night's sleep at the participants' homes. To capture prosocial preferences, participants played an incentivized public goods game in which they faced real monetary consequences. The whole-brain analyses showed that a higher relative slow-wave activity (SWA, an indicator of sleep depth) in a cluster of electrodes over the right temporoparietal junction (TPJ) was associated with increased prosocial preferences. Source localization and current source density analyses further support these findings. Recent sleep deprivation studies imply that sleeping enough makes us more prosocial; the present findings suggest that it is not only sleep duration, but particularly sufficient sleep depth in the TPJ that is positively related to prosociality. Because the TPJ plays a central role in social cognitive functions, we speculate that sleep depth in the TPJ, as reflected by relative SWA, might serve as a dispositional indicator of social cognition ability, which is reflected in prosocial preferences. These findings contribute to the emerging framework explaining the link between sleep and prosocial behavior by shedding light on the underlying mechanisms.

The importance of need-altruism and kin-altruism to blood donor behaviour for black and white people

BACKGROUND

Need-altruism (a preference to help people in need) and kin-altruism (a preference to help kin over non-kin) underlie two hypotheses for voluntary blood donation: (i) Need-altruism underlies motivations for volunteer blood donation and (ii) Black people express a stronger preference for kin-altruism, which is a potential barrier to donation. This paper tests these hypotheses and explores how need- and kin-altruism are associated with wider altruistic motivations, barriers, and strategies to encourage donation.

METHODS

We assessed need- and kin-altruism, other mechanisms-of-altruism (e.g., reluctant-altruism), barriers, strategies to encourage donation, donor status, and willingness-to-donate across four groups based on ethnicity (Black; White), nationality (British; Nigerian), and country-of-residence: (i) Black-British people (n = 395), and Black-Nigerian people (ii) in the UK (n = 97) or (iii) across the rest of the world (n = 101), and (v) White-British people in the UK (n = 452). We also sampled a Black-Nigerian Expert group (n = 60).

RESULTS

Need-altruism was higher in donors and associated with willingness-to-donate in non-donors. Levels of kin-altruism did not differ between Black and White people, but need-altruism was lower in Black-British people. Kin-altruism was associated with a preference for incentives, and need-altruism with a preference for recognition (e.g., a thank you) as well as an increased willingness-to-donate for Black non-donors. Need-altruism underlies a blood-donor-cooperative-phenotype.

CONCLUSION

Need-altruism is central to blood donation, in particular recruitment. Lower need-altruism may be a specific barrier for Black-British people. Kin-altruism is important for Black non-donors. The blood donor cooperative phenotype deserves further consideration. Implications for blood services are discussed.

Poor lie detection related to an under-reliance on statistical cues and overreliance on own behaviour

The surge of online scams is taking a considerable financial and emotional toll. This is partially because humans are poor at detecting lies. In a series of three online experiments (Nexp1 = 102, Nexp2 = 108, Nexp3 = 100) where participants are given the opportunity to lie as well as to assess the potential lies of others, we show that poor lie detection is related to the suboptimal computations people engage in when assessing lies. Participants used their own lying behaviour to predict whether other people lied, despite this cue being uninformative, while under-using more predictive statistical cues. This was observed by comparing the weights participants assigned to different cues, to those of a model trained on the ground truth. Moreover, across individuals, reliance on statistical cues was associated with better discernment, while reliance on one's own behaviour was not. These findings suggest scam detection may be improved by using tools that augment relevant statistical cues.

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.

Unravelling the many facets of human cooperation in an experimental study

Humans readily cooperate, even with strangers and without prospects of reciprocation. Despite thousands of studies, this finding is not well understood. Most studies focussed on a single aspect of cooperation and were conducted under anonymous conditions. However, cooperation is a multi-faceted phenomenon, involving generosity, readiness to share, fairness, trust, trustworthiness, and willingness to take cooperative risks. Here, we report findings of an experiment where subjects had to make decisions in ten situations representing different aspects of cooperation, both under anonymous and 'personalised' conditions. In an anonymous setting, we found considerable individual variation in each decision situation, while individuals were consistent both within and across situations. Prosocial tendencies such as generosity, trust, and trustworthiness were positively correlated, constituting a 'cooperativeness syndrome', but the tendency to punish non-cooperative individuals is not part of this syndrome. In a personalised setting, information on the appearance of the interaction partner systematically affected cooperation-related behaviour. Subjects were more cooperative toward interaction partners whose facial photographs were judged 'generous', 'trustworthy', 'not greedy', 'happy', 'attractive', and 'not angry' by a separate panel. However, individuals eliciting more cooperation were not more cooperative themselves in our experiment. Our study shows that a multi-faceted approach can reveal general behavioural tendencies underlying cooperation, but it also uncovers new puzzling features of human cooperation.

Warming up cool cooperators

Explaining why someone repeats high-cost cooperation towards non-reciprocating strangers is difficult. Warm glow offers an explanation. We argue that warm glow, as a mechanism to sustain long-term cooperation, cools off over time but can be warmed up with a simple intervention message. We tested our predictions in the context of repeat voluntary blood donation (high-cost helping of a non-reciprocating stranger) across 6 studies: a field-based experiment (n = 5,821) comparing warm-glow and impure-altruism messages; an implementation study comparing a 3-yr pre-implementation period among all first-time donors in Australia (N = 270,353) with a 2-yr post-implementation period (N = 170, 317); and 4 studies (n = 716, 1,124, 932, 1,592) exploring mechanisms. We show that there are relatively warm and cool cooperators, not cooling cooperators. Cooperation among cool cooperators is enhanced by a warm-glow-plus-identity message. Furthermore, the behavioural facilitation of future cooperation, by booking an appointment, is associated with being a warm cooperator. Societal implications are discussed.

Strategy evolution on dynamic networks

Models of strategy evolution on static networks help us understand how population structure can promote the spread of traits like cooperation. One key mechanism is the formation of altruistic spatial clusters, where neighbors of a cooperative individual are likely to reciprocate, which protects prosocial traits from exploitation. However, most real-world interactions are ephemeral and subject to exogenous restructuring, so that social networks change over time. Strategic behavior on dynamic networks is difficult to study, and much less is known about the resulting evolutionary dynamics. Here we provide an analytical treatment of cooperation on dynamic networks, allowing for arbitrary spatial and temporal heterogeneity. We show that transitions among a large class of network structures can favor the spread of cooperation, even if each individual social network would inhibit cooperation when static. Furthermore, we show that spatial heterogeneity tends to inhibit cooperation, whereas temporal heterogeneity tends to promote it. Dynamic networks can have profound effects on the evolution of prosocial traits, even when individuals have no agency over network structures.

Cooperating with Different Types of Strangers: The Influence of Guanxi Perception, Trust, and Responsibility

This study explored people's estimation of cooperative intention when paired with people with different types of relationships, and the mediating roles of trust and responsibility between guanxi perception and the estimation of cooperative intention. We recruited 398 university students from the Greater Bay Area of China to complete two public goods dilemma experiments. Study 1 manipulated the type of partner to be either family member, classmate, and stranger, representing different types of guanxi. Study 2 manipulated the type of partner to be either stranger with intermediary, stranger within ingroup, and complete stranger. In both studies, the mediating roles of trust and responsibility in the relationship between guanxi perception and the estimation of cooperative intention were tested. The results of study 1 showed that the participants' estimation of cooperative intention with a family member was higher than with acquaintances or with strangers. In study 2, the estimation of cooperative intention with stranger with intermediary was higher than with a stranger within one's ingroup or with a complete stranger. Multivariate analysis verified the mediating effects. The results are discussed with reference to why Chinese people treat different types of guanxi distinctly, especially to different types of strangers, and how guanxi perception, trust, and responsibility work together to the influence of the estimation of cooperative intention.

Who helped yesterday will help tomorrow: Trait and state components in prosocial goal realisation

The present study aims to disentangle the state and trait components of prosocial goal realisation, defined as a set of personally meaningful prosocial actions undertaken in natural settings. Based on a diary study with seven daily measurements from 180 participants (a total of 1005 data points), we performed temporal variance decomposition using the STARTS model. The observed individual scores are explained by: ST-a common trait factor, capturing variance stable across days; ART-a unique autoregressive trait factor, capturing variance changing from 1 day to the next; and S-state factors, a series of uncorrelated factors reflecting occasion-specific variance. The results demonstrate the relative stability of prosocial goal realisation, extending the knowledge on the state/trait distinction in actual prosocial behaviour.

Unselfish traits and social decision-making patterns characterize six populations of real-world extraordinary altruists

Acts of extraordinary, costly altruism, in which significant risks or costs are assumed to benefit strangers, have long represented a motivational puzzle. But the features that consistently distinguish individuals who engage in such acts have not been identified. We assess six groups of real-world extraordinary altruists who had performed costly or risky and normatively rare (<0.00005% per capita) altruistic acts: heroic rescues, non-directed and directed kidney donations, liver donations, marrow or hematopoietic stem cell donations, and humanitarian aid work. Here, we show that the features that best distinguish altruists from controls are traits and decision-making patterns indicating unusually high valuation of others' outcomes: high Honesty-Humility, reduced Social Discounting, and reduced Personal Distress. Two independent samples of adults who were asked what traits would characterize altruists failed to predict this pattern. These findings suggest that theories regarding self-focused motivations for altruism (e.g., self-enhancing reciprocity, reputation enhancement) alone are insufficient explanations for acts of real-world self-sacrifice.

Cooperative and conformist behavioural preferences predict the dual dimensions of political ideology

Decades of research suggest that our political differences are best captured by two dimensions of political ideology. The dual evolutionary framework of political ideology predicts that these dimensions should be related to variation in social preferences for cooperation and group conformity. Here, we combine data from a New Zealand survey and a suite of incentivised behavioural tasks (n = 991) to test whether cooperative and conformist preferences covary with a pair of widely used measures of the two dimensions of political ideology-Social Dominance Orientation (SDO) and Right Wing Authoritarianism (RWA)-and related policy views. As predicted, we find that cooperative behaviour is negatively related to SDO and economically conservative policy views, while conformist behaviour in the form of social information use is positively related to RWA and socially conservative policy views. However, we did not find the predicted relationships between punitive and rule following behaviours and RWA or socially conservative views, raising questions about the interpretation of punishment and rule following tasks and the nature of authoritarian conformist preferences. These findings reveal how cooperative and conformist preferences that evolved to help us navigate social challenges in our ancestral past continue to track our political differences even today.

Human and macaque pairs employ different coordination strategies in a transparent decision game

Many real-world decisions in social contexts are made while observing a partner's actions. To study dynamic interactions during such decisions, we developed a setup where two agents seated face-to-face to engage in game-theoretical tasks on a shared transparent touchscreen display ('transparent games'). We compared human and macaque pairs in a transparent version of the coordination game 'Bach-or-Stravinsky', which entails a conflict about which of two individually-preferred opposing options to choose to achieve coordination. Most human pairs developed coordinated behavior and adopted dynamic turn-taking to equalize the payoffs. All macaque pairs converged on simpler, static coordination. Remarkably, two animals learned to coordinate dynamically after training with a human confederate. This pair selected the faster agent's preferred option, exhibiting turn-taking behavior that was captured by modeling the visibility of the partner's action before one's own movement. Such competitive turn-taking was unlike the prosocial turn-taking in humans, who equally often initiated switches to and from their preferred option. Thus, the dynamic coordination is not restricted to humans but can occur on the background of different social attitudes and cognitive capacities in rhesus monkeys. Overall, our results illustrate how action visibility promotes the emergence and maintenance of coordination when agents can observe and time their mutual actions.

Partner choice does not predict prosociality across countries

Why does human prosociality vary around the world? Evolutionary models and laboratory experiments suggest that possibilities for partner choice (i.e. the ability to leave unprofitable relationships and strike up new ones) should promote cooperation across human societies. Leveraging the Global Preferences Survey (n = 27,125; 27 countries) and the World Values Survey (n = 54,728; 32 countries), we test this theory by estimating the associations between relational mobility, a socioecological measure of partner choice, and a wide variety of prosocial attitudes and behaviours, including impersonal altruism, reciprocity, trust, collective action and moral judgements of antisocial behaviour. Contrary to our pre-registered predictions, we found little evidence that partner choice is related to prosociality across countries. After controlling for shared causes of relational mobility and prosociality - environmental harshness, subsistence style and geographic and linguistic proximity - we found that only altruism and trust in people from another religion are positively related to relational mobility. We did not find positive relationships between relational mobility and reciprocity, generalised trust, collective action or moral judgements. These findings challenge evolutionary theories of human cooperation which emphasise partner choice as a key explanatory mechanism, and highlight the need to generalise models and experiments to global samples.

Authority or Autonomy? Exploring Interactions between Central and Peer Punishments in Risk-Resistant Scenarios

Game theory provides a powerful means to study human cooperation and better understand cooperation-facilitating mechanisms in general. In classical game-theoretic models, an increase in group cooperation constantly increases people's gains, implying that individual gains are a continuously varying function of the cooperation rate. However, this is inconsistent with the increasing number of risk-resistant scenarios in reality. A risk-resistant scenario means once a group does not successfully resist the risk, all individuals lose their resources, such as a community coping with COVID-19 and a village resisting a flood. In other words, individuals' gains are segmented about the collaboration rate. This paper builds a risk-resistant model to explore whether punishment still promotes collaboration when people resist risk. The results show that central and peer punishments can both encourage collaboration but with different characteristics under different risk-resistant scenarios. Specifically, central punishment constrains the collaboration motivated by peer punishment regardless of risk, while peer punishment limits the collaboration induced by central punishment only when the risk is high. Our findings provide insights into the balance between peer punishment from public autonomy and central punishment from central governance, and the proposed model paves the way for the development of richer risk-resistant models.

Variability in repeated economic games: comparing trust game decisions to other social trust measures

Economic games are well-established tools that offer a convenient approach to study social behaviour. Although widely used, recent evidence suggests that decisions made in the context of standard economic games are less predictive of real-world behaviour than previously assumed self-reported questionnaires. A possible explanation for this discrepancy is that economic games decisions in the laboratory are more likely to be influenced by the current situation, while questionnaires are specifically designed to measure people's average behaviour across a long period of time. To test this hypothesis, we performed a longitudinal study where 275 respondents played 16 Trust games every two days within a three-week period, and filled out a questionnaire that measures social trust. This study confirmed the instability of our measure of trust behaviour over time and the substantial stability of questionnaire responses. However, we found a significant association between self-reported social trust and participants' average behaviour in the trust game measured across sessions, but also with participants' behaviour measured only in Session 1. Nevertheless, analysis of behavioural changes in the Trust games over time revealed different behavioural profiles, highlighting how economic games and questionnaires can complement each other in the study of social trust.

Intrinsic brain activity patterns across large-scale networks predict reciprocity propensity

Reciprocity is prevalent across human societies, but individuals are heterogeneous regarding their reciprocity propensity. Although a large body of task-based brain imaging measures has shed light on the neural underpinnings of reciprocity at group level, the neural basis underlying the individual differences in reciprocity propensity remains largely unclear. Here, we combined brain imaging and machine learning techniques to individually predict reciprocity propensity from resting-state brain activity measured by fractional amplitude of low-frequency fluctuation. The brain regions contributing to the prediction were then analyzed for functional connectivity and decoding analyses, allowing for a data-driven quantitative inference on psychophysiological functions. Our results indicated that patterns of resting-state brain activity across multiple brain systems were capable of predicting individual reciprocity propensity, with the contributing regions distributed across the salience (e.g., ventrolateral prefrontal cortex), fronto-parietal (e.g., dorsolateral prefrontal cortex), default mode (e.g., ventromedial prefrontal cortex), and sensorimotor (e.g., supplementary motor area) networks. Those contributing brain networks are implicated in emotion and cognitive control, mentalizing, and motor-based processes, respectively. Collectively, these findings provide novel evidence on the neural signatures underlying the individual differences in reciprocity, and lend support the assertion that reciprocity emerges from interactions among regions embodied in multiple large-scale brain networks.

Cooperative phenotype predicts climate change belief and pro-environmental behaviour

Understanding the psychological causes of variation in climate change belief and pro-environmental behaviour remains an urgent challenge for the social sciences. The “cooperative phenotype” is a stable psychological preference for cooperating in social dilemmas that involve a tension between individual and collective interest. Since climate change poses a social dilemma on a global scale, this issue may evoke similar psychological processes as smaller social dilemmas. Here, we investigate the relationships between the cooperative phenotype and climate change belief and behaviour with a representative sample of New Zealanders (N = 897). By linking behaviour in a suite of economic games to self-reported climate attitudes, we show robust positive associations between the cooperative phenotype and both climate change belief and pro-environmental behaviour. Furthermore, our structural equation models support a motivated reasoning account in which the relationship between the cooperative phenotype and pro-environmental behaviour is mediated by climate change belief. These findings suggest that common psychological mechanisms underlie cooperation in both micro-scale social dilemmas and larger-scale social dilemmas like climate change.

Varieties of normative understanding and their relation to sharing behavior in preschool children

Children increasingly appreciate normative obligations and share resources across the preschool years. But the internal structure and behavioral relevance of normative expressions in the context of sharing-that is, the relation with children's own sharing behavior-remains disputed. Here, 4- to 6-year-old children (N = 90; 37 female) observed protagonists sharing or not sharing resources. As measures of normative expressions, children's evaluation, punishment acceptability, non-costly punishment, and costly punishment of the protagonists as well as their moral self-concept were assessed. To measure actual prosocial behavior, children had the possibility to share resources. A factor analysis revealed that the variety of normative expressions constitutes two distinct factors: normative representation (evaluation and hypothetical punishment) and norm enforcement (actual non-costly and costly punishment). Children's moral self-concept was the only normative expression that related to sharing behavior. Person-centered analyses suggest some consistency in individual differences across normative and prosocial development, with normative expressions and sharing behavior being aligned for some children on a low level and for some children on a high level. This study advances our understanding of early normative development and highlights the internal structure of normative stances during the preschool years.

Key individuals catalyse intergroup violence

Intergroup violence is challenging to understand: why do individuals cooperate to harm members of other groups when they themselves may be killed or injured? Despite progress in understanding the evolutionary and proximate mechanisms that underlie violence, we still have little insight into the processes that lead to the emergence of coalitionary aggression. We argue that an overlooked component is the presence of individuals who have a crucial role in initiating violence. In instigating intergroup violence, these key individuals may expect to face lower costs, receive greater benefits, or garner benefits that have a greater value to them than others. Alternatively, key individuals may be motivated by individual traits such as increased boldness, propensity for aggression or exploratory behaviour. Key individuals catalyse the emergence of coalitionary violence through one of several processes including altering the costs and benefits that accrue to others, paying a greater share of the startup costs, signalling privileged knowledge, or providing coordination, among other factors. Here we integrate diverse lines of empirical research from humans and non-human animals demonstrating that inter-individual variation is an important factor in the emergence of intergroup violence. Focusing on the role of key individuals provides new insights into how and why violence emerges. This article is part of the theme issue 'Intergroup conflict across taxa'.

Advertising cooperative phenotype through costly signals facilitates collective action

Around the world, people engage in practices that involve self-inflicted pain and apparently wasted resources. Researchers theorized that these practices help stabilize within-group cooperation by assorting individuals committed to collective action. While this proposition was previously studied using existing religious practices, we provide a controlled framework for an experimental investigation of various predictions derived from this theory. We recruited 372 university students in the Czech Republic who were randomly assigned into either a high-cost or low-cost condition and then chose to play a public goods game (PGG) either in a group that wastes money to signal commitment to high contributions in the game or to play in the group without such signals. We predicted that cooperators would assort in the high-cost revealed group and that, despite these costs, they would contribute more to the common pool and earn larger individual rewards over five iterations of PGG compared with the concealed group and participants in the low-cost condition. The results showed that the assortment of cooperators was more effective in the high-cost condition and translated into larger contributions of the remaining endowment to the common pool, but participants in the low-cost revealed group earned the most. We conclude that costly signals can serve as an imperfect assorting mechanism, but the size of the costs needs to be carefully balanced with potential benefits to be profitable.

Observing others give & take: A computational account of bystanders' feelings and actions

Social interactions influence people's feelings and behavior. Here, we propose that a person's well-being is influenced not only by interactions they experience themselves, but also by those they observe. In particular, we test and quantify the influence of observed selfishness and observed inequality on a bystanders' feelings and non-costly punishment decisions. We developed computational models that relate others' (un)selfish acts to observers' emotional reactions and punishment decisions. These characterize the rules by which others' interactions are transformed into bystanders' reactions, and successfully predict those reactions in out-of-sample participants. The models highlight the impact of two social values-'selfishness aversion' and 'inequality aversion'. As for the latter we find that even small violations from perfect equality have a disproportionately large impact on feelings and punishment. In this age of internet and social media we constantly observe others' online interactions, in addition to in-person interactions. Quantifying the consequences of such observations is important for predicting their impact on society.

Neural mechanisms of the mood effects on third‐party responses to injustice after unfair experiences

Behavioral decision theory argues that humans can adjust their third‐party responses (e.g., punishment and compensation) to injustice by integrating unfair experiences. Typically, the mood plays an important role in such a decision‐making process. However, the underlying neurocognitive bases remain largely unclear. We first employ a modified third‐party justice game in which an allocator split an amount of money between oneself and a receiver. The participants can reapportion the money as observers by choosing from the following three costly options: compensate the receiver, accept the current allocation, or punish the allocator. Then, a second‐party pseudo interaction is conducted where participants receive more (i.e., advantageous unfair experience) or less (i.e., disadvantageous unfair experience) than others. Finally, participants perform the third‐party justice game again after unfair experiences. Here, we use functional near‐infrared spectroscopy (fNIRS) to measure participants' brain activities during third‐party responses to injustice. We find participants compensate more to the receiver after advantageous unfair experience, which involved enhanced positive emotion, weakened sense of unfairness, and is linked with increased activity in the right dorsolateral prefrontal cortex (rDLPFC). In contrast, participants punish more on the allocator after disadvantageous unfair experience, which might primarily stem from their negative emotional responses, strong sense of unfairness, and is associated with significantly decreased activity in the rDLPFC. Our results suggest that third‐party compensation and punishment involved differential psychological and neural bases. Our findings highlight the crucial roles of second‐party unfair experiences and the corresponding mood responses in third‐party responses to unfairness, and unravel the intermediate neural architecture.

Interpersonal problems and cooperative behavior in patients suffering from prolonged grief disorder as compared to bereaved healthy controls

OBJECTIVES

Interpersonal factors, such as impairments in social interaction or lack of social support, have an important share when it comes to the development, maintenance, and progression of various mental disorders.

METHODS

Individuals suffering from prolonged grief disorder (PGD) and matched bereaved healthy controls (n = 54) underwent a thorough diagnostic procedure, further completed the Inventory of Interpersonal Problems (IIP-D-32), and participated in a finitely iterated prisoner's dilemma (FIPD).

RESULTS

Individuals suffering from PGD reported significantly more interpersonal problems. Both groups behaved differently in the FIPD with healthy controls being more carefully, adapting their behavior more flexible, whereas PGD patients displayed a lower responsiveness, which may indicate an inability to adapt to changes in relationships.

CONCLUSION

We conclude that interpersonal problems appear to be a relevant feature of PGD. Future studies need to clarify the causal relation behind this link, and should also include measures of attachment, social support, and disconnectedness.

Investigating adult age differences in real-life empathy, prosociality, and well-being using experience sampling

While the importance of social affect and cognition is indisputable throughout the adult lifespan, findings of how empathy and prosociality develop and interact across adulthood are mixed and real-life data are scarce. Research using ecological momentary assessment recently demonstrated that adults commonly experience empathy in daily life. Furthermore, experiencing empathy was linked to higher prosocial behavior and subjective well-being. However, to date, it is not clear whether there are adult age differences in daily empathy and daily prosociality and whether age moderates the relationship between empathy and prosociality across adulthood. Here we analyzed experience-sampling data collected from participants across the adult lifespan to study age effects on empathy, prosocial behavior, and well-being under real-life circumstances. Linear and quadratic age effects were found for the experience of empathy, with increased empathy across the three younger age groups (18 to 45 years) and a slight decrease in the oldest group (55 years and older). Neither prosocial behavior nor well-being showed significant age-related differences. We discuss these findings with respect to (partially discrepant) results derived from lab-based and traditional survey studies. We conclude that studies linking in-lab experiments with real-life experience-sampling may be a promising venue for future lifespan studies.

Latent motives guide structure learning during adaptive social choice

Predicting the behaviour of others is an essential part of social cognition. Despite its ubiquity, social prediction poses a poorly understood generalization problem: we cannot assume that others will repeat past behaviour in new settings or that their future actions are entirely unrelated to the past. We demonstrate that humans solve this challenge using a structure learning mechanism that uncovers other people's latent, unobservable motives, such as greed and risk aversion. In four studies, participants (N = 501) predicted other players' decisions across four economic games, each with different social tensions (for example, Prisoner's Dilemma and Stag Hunt). Participants achieved accurate social prediction by learning the stable motivational structure underlying a player's changing actions across games. This motive-based abstraction enabled participants to attend to information diagnostic of the player's next move and disregard irrelevant contextual cues. Participants who successfully learned another's motives were more strategic in a subsequent competitive interaction with that player in entirely new contexts, reflecting that social structure learning supports adaptive social behaviour.

Collective minds: social network topology shapes collective cognition

Human cognition is not solitary, it is shaped by collective learning and memory. Unlike swarms or herds, human social networks have diverse topologies, serving diverse modes of collective cognition and behaviour. Here, we review research that combines network structure with psychological and neural experiments and modelling to understand how the topology of social networks shapes collective cognition. First, we review graph-theoretical approaches to behavioural experiments on collective memory, belief propagation and problem solving. These results show that different topologies of communication networks synchronize or integrate knowledge differently, serving diverse collective goals. Second, we discuss neuroimaging studies showing that human brains encode the topology of one's larger social network and show similar neural patterns to neural patterns of our friends and community ties (e.g. when watching movies). Third, we discuss cognitive similarities between learning social and non-social topologies, e.g. in spatial and associative learning, as well as common brain regions involved in processing social and non-social topologies. Finally, we discuss recent machine learning approaches to collective communication and cooperation in multi-agent artificial networks. Combining network science with cognitive, neural and computational approaches empowers investigating how social structures shape collective cognition, which can in turn help design goal-directed social network topologies. This article is part of a discussion meeting issue 'The emergence of collective knowledge and cumulative culture in animals, humans and machines'.

Cognitive load decreases cooperation and moral punishment in a Prisoner's Dilemma game with punishment option

The present study serves to test whether cooperation and moral punishment are affected by cognitive load. Dual-process theories postulate that moral behavior is intuitive which leads to the prediction that cooperation and moral punishment should remain unaffected or may even increase when cognitive load is induced by a secondary task. However, it has also been proposed that cognitive control and deliberation are necessary to choose an economically costly but morally justified option. A third perspective implies that the effects of cognitive load may depend on the specific processes involved in social dilemmas. In the present study, participants played a simultaneous Prisoner’s Dilemma game with a punishment option. First, both players decided to cooperate or defect. Then they had the opportunity to punish the partners. In the cognitive-load group, cognitive load was induced by a continuous tone classification task while the no-load group had no distractor task. Under cognitive load, cooperation and moral punishment decreased in comparison to the no-load condition. By contrast, hypocritical and antisocial punishment were not influenced by the dual-task manipulation. Increased cognitive load was associated with a bias to punish the partners irrespective of the outcome of the Prisoner’s Dilemma game, suggesting that punishment was applied less purposefully in the cognitive-load condition. The present findings are thus in line with the idea that the availability of cognitive resources does not always have a suppressive effect on moral behaviors, but can have facilitating effects on cooperation and moral punishment.

Harsh but Expedient: Dominant Leaders Increase Group Cooperation via Threat of Punishment

Dominant leadership is, surprisingly, on the rise globally. Previous studies have found that intergroup conflict increases followers' support for dominant leaders, but identifying the potential benefits that such leaders can supply is crucial to explaining their rise. We took a behavioral-economics approach in Study 1 (N = 288 adults), finding that cooperation among followers increases under leaders with a dominant reputation. This pattern held regardless of whether dominant leaders were assigned to groups, elected through a bidding process, or leading under intergroup competition. Moreover, Studies 2a to 2e (N = 1,022 adults) show that impressions of leader dominance evoked by personality profiles, authoritarian attitudes, or physical formidability similarly increase follower cooperation. We found a weaker but nonsignificant trend when dominance was cued by facial masculinity and no evidence when dominance was cued by aggressive disposition in a decision game. These findings highlight the unexpected benefits that dominant leaders can bestow on group cooperation through threat of punishment.

No effect of 'watching eyes': An attempted replication and extension investigating individual differences

Some evidence suggests that people behave more cooperatively and generously when observed or in the presence of images of eyes (termed the 'watching eyes' effect). Eye images are thought to trigger feelings of observation, which in turn motivate people to behave more cooperatively to earn a good reputation. However, several recent studies have failed to find evidence of the eyes effect. One possibility is that inconsistent evidence in support of the eyes effect is a product of individual differences in sensitivity or susceptibility to the cue. In fact, some evidence suggests that people who are generally more prosocial are less susceptible to situation-specific reputation-based cues of observation. In this paper, we sought to (1) replicate the eyes effect, (2) replicate the past finding that people who are dispositionally less prosocial are more responsive to observation than people who are more dispositionally more prosocial, and (3) determine if this effect extends to the watching eyes effect. Results from a pre-registered study showed that people did not give more money in a dictator game when decisions were made public or in the presence of eye images, even though participants felt more observed when decisions were public. That is, we failed to replicate the eyes effect and observation effect. An initial, but underpowered, interaction model suggests that egoists give less than prosocials in private, but not public, conditions. This suggests a direction for future research investigating if and how individual differences in prosociality influence observation effects.

Improving the measurement of prosociality through aggregation of game behavior

Prior research has found that people's choices in economic games are often only modestly related to their prosocial personality traits and to mundane prosocial behaviors. The present article reviews the recent literature showing that the strength of these relationships depends on the level of aggregation. Specifically, we demonstrate an increase in behavioral consistency after horizontal aggregation (across multiple game types), vertical aggregation (across multiple game variants), and a combination thereof. Moreover, we show that aggregation increases the magnitude of the relationships of game behavior with prosocial personality and mundane prosocial behavior. These findings illustrate that economic games can genuinely capture a core facet of human prosociality - but that their capacity for doing so is greater when multiple game behaviors are considered.

Age-Related Changes in the Role of Social Motivation: Implications for Healthy Aging

Prior research has established the importance of social relations and social embeddedness for motivation in healthy aging. Thus, social orientation appears to be essential for understanding healthy aging. This article focuses particularly on age-related changes in goals concerning social orientation, such as increased prioritization of emotional goals, increased prosociality/altruistic motives, generativity, and ego transcendence. We then consider open questions regarding gaps in the links between goals related to social orientation and healthy aging, as well as the implications of theories and research on social goals for leveraging motivation to promote healthy aging. In particular, interventions to promote healthy behavior in late life may be most effective when they match the themes of older adults' strivings to find meaning and purpose in their personal goals.

How Do Basic Personality Traits Map Onto Moral Judgments of Fairness-Related Actions?

Reliance on fairness norms is a core feature of moral behavior and judgment, and is conceptually and empirically linked with basic personality dimensions. However, the specific nature of these links is poorly understood. In this study ( N = 313, 68% female), we employed a novel third-party judgment paradigm, in which participants made moral judgments of various sharing actions of virtual others. This allowed us to capture individual variation in the relative importance of several fairness norms. We correlated these norm profiles with Big Five personality traits. We observed distinct associations between agreeableness, conscientiousness, openness, and extraversion and estimates of the importance of generosity, selfishness, relative generosity, and relative selfishness norms. Comparisons of these associations at the domain- versus facet-level of personality traits suggested these relations are specific to domain-level traits. These findings are an important step toward unraveling the complex links between fairness norms and basic personality traits.

Constructing the Facets of Altruistic Behaviors (FAB) Scale

Abstract. Behavior is effectively altruistic to the degree that it is costly for the actor while benefiting others. In a series of preregistered studies, we constructed a 15-item self-report scale assessing three different facets of altruistic behavioral traits: help-giving, moral courage, and peer punishment. Item selection was performed with the help of Ant Colony Optimization (ACO) procedures as implemented in the stuart package for R. Confirmatory factor analysis of the three-factor measurement model showed excellent fit, outperforming classical item selection procedures. The scale was structure-validated in a second sample using a multiple group model that showed full measurement and structural invariance. A pilot study shows correlations of the subscales with economic game decisions. We discuss the scale structure and potential applications.

Neuroscientific approaches to study prosociality

Prosociality is a core feature of human functioning and has been a topic of interest across disciplinary boundaries for decades. In this review, we highlight different neuroscientific approaches that have enriched traditional psychological methods for studying prosocial behavior among individuals and groups. First, we outline findings from task-based neuroimaging studies that provide correlational evidence for the involvement of different neural mechanisms in prosocial behavior. Next, we present different brain stimulation studies that show several brain areas to be causally related to prosocial behavior. Furthermore, we outline the task-independent neural trait approach that quantifies temporally stable brain-based characteristics in an effort to uncover sources of interindividual differences in prosocial preferences. We discuss how the findings from these approaches have contributed to our understanding of prosocial behavior and suggest directions for future research.

Hyper-altruistic behavior vanishes with high stakes

Using an incentivized experiment with statistical power, this paper explores the role of stakes in charitable giving of lottery prizes, where subjects commit to donate a fraction of the prize before they learn the outcome of the lottery. We study three stake levels: 5€ (n = 177), 100€ (n = 168), and 1,000€ (n = 171). Although the donations increase in absolute terms as the stakes increase, subjects decrease the donated fraction of the pie. However, people still share roughly 20% of 1,000€, an amount as high as the average monthly salary of people at the age of our subjects. The number of people sharing 50% of the pie is remarkably stable across stakes, but donating the the whole pie-the modal behavior in charity-donation experiments-disappears with stakes. Such hyper-altruistic behavior thus seems to be an artifact of the stakes typically employed in economic and psychological experiments. Our findings point out that sharing with others is a prevalent human feature, but stakes are an important determinant of sharing. Policies promoted via prosocial frames (e.g., stressing the effects of mask-wearing or social distancing on others during the Covid-19 pandemic or environmentally-friendly behaviors on future generations) may thus be miscalibrated if they disregard the stakes at play.

The dispositional basis of human prosociality

Individual differences in prosocial behavior have been consistently observed in a variety of contexts. Here, we summarize and critically discuss recent developments in two research agendas on the dispositional basis of human prosociality: a personality approach, proposing a variety of trait concepts and corresponding measures to predict prosocial behavior in different situations; and a behavioral consistency approach, testing for consistency in prosocial behaviors and its underlying latent disposition(s) across situations. Drawing on different properties of situations (so-called situational affordances), we outline a theoretical framework that can help integrate these so far hardly connected research agendas. We also point out limitations of prior research, such as a lack of theory, and provide suggestions on how to overcome them.

Human Cooperation and the Crises of Climate Change, COVID-19, and Misinformation

Contemporary society is facing many social dilemmas-including climate change, COVID-19, and misinformation-characterized by a conflict between short-term self-interest and longer-term collective interest. The climate crisis requires paying costs today to benefit distant others (and oneself) in the future. The COVID-19 crisis requires the less vulnerable to pay costs to benefit the more vulnerable in the face of great uncertainty. The misinformation crisis requires investing effort to assess truth and abstain from spreading attractive falsehoods. Addressing these crises requires an understanding of human cooperation. To that end, we present (a) an overview of mechanisms for the evolution of cooperation, including mechanisms based on similarity and interaction; (b) a discussion of how reputation can incentivize cooperation via conditional cooperation and signaling; and (c) a review of social preferences that undergird the proximate psychology of cooperation, including positive regard for others, parochialism, and egalitarianism. We discuss the three focal crises facing our society through the lens of cooperation, emphasizing how cooperation research can inform our efforts to address them. Expected final online publication date for the Annual Review of Psychology, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Neurocomputational models of altruistic decision-making and social motives: Advances, pitfalls, and future directions

This article discusses insights from computational models and social neuroscience into motivations, precursors, and mechanisms of altruistic decision-making and other-regard. We introduce theoretical and methodological tools for researchers who wish to adopt a multilevel, computational approach to study behaviors that promote others' welfare. Using examples from recent studies, we outline multiple mental and neural processes relevant to altruism. To this end, we integrate evidence from neuroimaging, psychology, economics, and formalized mathematical models. We introduce basic mechanisms-pertinent to a broad range of value-based decisions-and social emotions and cognitions commonly recruited when our decisions involve other people. Regarding the latter, we discuss how decomposing distinct facets of social processes can advance altruistic models and the development of novel, targeted interventions. We propose that an accelerated synthesis of computational approaches and social neuroscience represents a critical step towards a more comprehensive understanding of altruistic decision-making. We discuss the utility of this approach to study lifespan differences in social preference in late adulthood, a crucial future direction in aging global populations. Finally, we review potential pitfalls and recommendations for researchers interested in applying a computational approach to their research. This article is categorized under: Economics > Interactive Decision-Making Psychology > Emotion and Motivation Neuroscience > Cognition Economics > Individual Decision-Making.

Age-related differences in strategic competition

Understanding how people of different ages decide in competition is a question of theoretical and practical importance. Using an experimental laboratory approach, this research investigates the ability of younger and older adults to think and act strategically with equal or unequal resources. In zero-sum games of resource allocation, younger adults (19-35 years) and older adults (65-81 years) made strategic decisions in competition against opponents of a similar age (Study 1; N = 120) or different age (Study 2; N = 120). The findings highlight people's ability to make good interpersonal decisions in complex scenarios: Both younger and older adults were aware of their relative strength (in terms of material resources) and allocated their resources adaptively. When competing against opponents of a similar age, people's gains were in line with game-theoretic predictions. However, younger adults made superior strategic allocations and won more frequently when competing against older adults. Measures of fluid cognitive and numerical abilities correlated with strategic behavior in interpersonal competition.

(Mis)perceiving cooperativeness

Cooperation is crucial for the success of social interactions. Given its importance, humans should readily be able to use available cues to predict how likely others are to cooperate. Here, we review the empirical literature on how accurate such predictions are. To this end, we distinguish between three classes of cues: behavioral (including past decisions), personal (including gender, attractiveness, and group membership) and situational (including the benefits to cooperation and the ability to communicate with each other). We discuss (i) how each cue correlates with future cooperative decisions and (ii) whether people correctly anticipate each cue's predictive value. We find that people are fairly accurate in interpreting behavioral and situational cues. However, they often misperceive the value of personal cues.