Variation in cooperative behaviour within a single city

Human cooperative behaviour, as assayed by decisions in experimental economic dilemmas such as the Dictator Game, is variable across human populations. Within-population variation has been less well studied, especially within industrial societies. Moreover, little is known about the extent to which community-level variation in Dictator Game behaviour relates to community-level variation in real-world social behaviour. We chose two neighbourhoods of the city of Newcastle upon Tyne that were similar in most regards, but at opposite ends of the spectrum in terms of level of socioeconomic deprivation. We administered Dictator Games to randomly-selected residents, and also gathered a large number of more naturalistic measures of cooperativeness. There were dramatic differences in Dictator Game behaviour between the two neighbourhoods, with the mean allocation to the other player close to half the stake in the affluent neighbourhood, and close to one tenth of the stake in the deprived neighbourhood. Moreover, the deprived neighbourhood was also characterised by lower self-reported social capital, higher frequencies of crime and antisocial behaviour, a higher frequency of littering, and less willingness to take part in a survey or return a lost letter. On the other hand, there were no differences between the neighbourhoods in terms of the probability of helping a person who dropped an object, needed directions to a hospital, or needed to make change for a coin, and people on the streets were less likely to be alone in the deprived neighbourhood than the affluent one. We conclude that there can be dramatic local differences in cooperative behaviour within the same city, and that these need further theoretical explanation.     

How Much Is Our Fairness Worth? The Effect of Raising Stakes on Offers by Proposers and Minimum Acceptable Offers in Dictator and Ultimatum Games

Background

The aim of this study was to determine whether people respond differently to low and high stakes in Dictator and Ultimatum Games. We assumed that if we raised the stakes high enough, we would observe more self-orientated behavior because fairness would become too costly, in spite of a possible risk of a higher punishment.

Methods

A questionnaire was completed by a sample of 524 university students of biology. A mixed linear model was used to test the relation between the amount at stake (CZK 20, 200, 2,000, 20,000 and 200,000, i.e., approximately $1–$10,000) and the shares, as well as the subjects’ gender and the design of the study (single vs. multiple games for different amounts).

Results

We have discovered a significant relationship between the amount at stake and the minimum acceptable offer in the Ultimatum Game and the proposed shares in both Ultimatum and Dictator Games (p = 0.001, p<0.001, p = 0.0034). The difference between playing a single game or more games with several amounts at stake did not influence the relation between the stakes and the offered and minimum acceptable shares. Women proved significantly more generous than men in their offers in the Dictator Game (p = 0.007).

Conclusion

Our results suggest that people’s behavior in the Dictator and Ultimatum Games depends on the amount at stake. The players tended to lower their relative proposed shares, as well as their relative minimum acceptable offers. We propose that the Responders’ sense of equity and fair play depends on the stakes because of the costs of maintaining fairness. However, our results also suggest that the price of fairness is very high and that it is very difficult, probably even impossible, to buy the transition of Homo sociologicus into Homo economicus.     

The watching eyes effect in the Dictator Game: it's not how much you give,it's being seen to give something

In a classic study, Haley and Fessler showed that displaying subtle eye-like stimuli caused participants to behave more generously in the Dictator Game. Since their paper was published, there have been both successful replications and null results reported in the literature. However, it is important to clarify that two logically separable effects were found in their original experiment: watching eyes made the mean donation higher, and also increased the probability of donating something rather than nothing. Here, we report a replication study with 118 participants, in which we found that watching eyes significantly increased the probability of donating something, but did not increase the mean donation. Results did not depend on the sex of the participants or the sex of the eyes. We also present a meta-analysis of the seven studies of watching eye effects in the Dictator Game published to date. Combined, these studies total 887 participants, and show that although watching eyes do not reliably increase mean donations, they do reliably increase the probability of donating something rather than nothing (combined odds ratio 1.39). We conclude that the watching eyes effect in the Dictator Game is robust, but its interpretation may require refinement. Rather than making people directionally more generous, it may be that watching eyes reduce variation in social behavior.     

Anonymity versus Privacy in the Dictator Game: Revealing Donor Decisions to Recipients Does Not Substantially Impact Donor Behavior

Anonymity is often offered in economic experiments in order to eliminate observer effects and induce behavior that would be exhibited under private circumstances. However, anonymity differs from privacy in that interactants are only unaware of each others'' identities, while having full knowledge of each others'' actions. Such situations are rare outside the laboratory and anonymity might not meet the requirements of some participants to psychologically engage as if their actions were private. In order to explore the impact of a lack of privacy on prosocial behaviors, I expand on a study reported in Dana et al. (2006) in which recipients were left unaware of the Dictator Game and given donations as “bonuses” to their show-up fees for other tasks. In the current study, I explore whether differences between a private Dictator Game (sensu Dana et al. (2006)) and a standard anonymous one are due to a desire by dictators to avoid shame or to pursue prestige. Participants of a Dictator Game were randomly assigned to one of four categories—one in which the recipient knew of (1) any donation by an anonymous donor (including zero donations), (2) nothing at all, (3) only zero donations, and (4) and only non-zero donations. The results suggest that a lack of privacy increases the shame that selfish-acting participants experience, but that removing such a cost has only minimal effects on actual behavior.     

Individual differences in allocation of funds in the dictator game associated with length of the arginine vasopressin 1a receptor RS3 promoter region and correlation between RS3 length and hippocampal mRNA

Human altruism is a widespread phenomenon that puzzled evolutionary biologists since Darwin. Economic games illustrate human altruism by showing that behavior deviates from economic predictions of profit maximization. A game that most plainly shows this altruistic tendency is the Dictator Game. We hypothesized that human altruistic behavior is to some extent hardwired and that a likely candidate that may contribute to individual differences in altruistic behavior is the arginine vasopressin 1a (AVPR1a) receptor that in some mammals such as the vole has a profound impact on affiliative behaviors. In the current investigation, 203 male and female university students played an online version of the Dictator Game, for real money payoffs. All subjects and their parents were genotyped for AVPR1a RS1 and RS3 promoter-region repeat polymorphisms. Parents did not participate in online game playing. As variation in the length of a repetitive element in the vole AVPR1a promoter region is associated with differences in social behavior, we examined the relationship between RS1 and RS3 repeat length (base pairs) and allocation sums. Participants with short versions (308-325 bp) of the AVPR1a RS3 repeat allocated significantly (likelihood ratio = 14.75, P = 0.001, df = 2) fewer shekels to the 'other' than participants with long versions (327-343 bp). We also implemented a family-based association test, UNPHASED, to confirm and validate the correlation between the AVPR1a RS3 repeat and monetary allocations in the dictator game. Dictator game allocations were significantly associated with the RS3 repeat (global P value: likelihood ratio chi(2) = 11.73, df = 4, P = 0.019). The association between the AVPR1a RS3 repeat and altruism was also confirmed using two self-report scales (the Bardi-Schwartz Universalism and Benevolence Value-expressive Behavior scales). RS3 long alleles were associated with higher scores on both measures. Finally, long AVPR1a RS3 repeats were associated with higher AVPR1a human post-mortem hippocampal messenger RNA levels than short RS3 repeats (one-way analysis of variance (ANOVA): F = 15.04, P = 0.001, df = 14) suggesting a functional molecular genetic basis for the observation that participants with the long RS3 repeats allocate more money than participants with the short repeats. This is the first investigation showing that a common human polymorphism, with antecedents in lower mammals, contributes to decision making in an economic game. The finding that the same gene contributing to social bonding in lower animals also appears to operate similarly in human behavior suggests a common evolutionary mechanism.     

Action being character: a promising perspective on the solution concept of game theory

The inconsistency of predictions from solution concepts of conventional game theory with experimental observations is an enduring question. These solution concepts are based on the canonical rationality assumption that people are exclusively self-regarding utility maximizers. In this article, we think this assumption is problematic and, instead, assume that rational economic agents act as if they were maximizing their implicit utilities, which turns out to be a natural extension of the canonical rationality assumption. Implicit utility is defined by a player's character to reflect his personal weighting between cooperative, individualistic, and competitive social value orientations. The player who actually faces an implicit game chooses his strategy based on the common belief about the character distribution for a general player and the self-estimation of his own character, and he is not concerned about which strategies other players will choose and will never feel regret about his decision. It is shown by solving five paradigmatic games, the Dictator game, the Ultimatum game, the Prisoner's Dilemma game, the Public Goods game, and the Battle of the Sexes game, that the framework of implicit game and its corresponding solution concept, implicit equilibrium, based on this alternative assumption have potential for better explaining people's actual behaviors in social decision making situations.     

Empathy leads to fairness

In the Ultimatum Game, two players are asked to split a prize. The first player, the proposer, makes an offer of how to split the prize. The second player, the responder, either accepts the offer, in which case the prize is split as agreed, or rejects it, in which case neither player receives anything. The rational strategy suggested by classical game theory is for the proposer to offer the smallest possible positive share and for the responder to accept. Humans do not play this way, however, and instead tend to offer 50% of the prize and to reject offers below 20%. Here we study the Ultimatum Game in an evolutionary context and show that empathy can lead to the evolution of fairness. Empathy means that individuals make offers which they themselves would be prepared to accept.     

A positive effect of flowers rather than eye images in a large-scale, cross-cultural dictator game

People often consider how their behaviour will be viewed by others, and may cooperate to avoid gaining a bad reputation. Sensitivity to reputation may be elicited by subtle social cues of being watched: previous studies have shown that people behave more cooperatively when they see images of eyes rather than control images. Here, we tested whether eye images enhance cooperation in a dictator game, using the online labour market Amazon Mechanical Turk (AMT). In contrast to our predictions and the results of most previous studies, dictators gave away more money when they saw images of flowers rather than eye images. Donations in response to eye images were not significantly different to donations under control treatments. Dictator donations varied significantly across cultures but there was no systematic variation in responses to different image types across cultures. Unlike most previous studies, players interacting via AMT may feel truly anonymous when making decisions and, as such, may not respond to subtle social cues of being watched. Nevertheless, dictators gave away similar amounts as in previous studies, so anonymity did not erase helpfulness. We suggest that eye images might only promote cooperative behaviour in relatively public settings and that people may ignore these cues when they know their behaviour is truly anonymous.     

Characteristics of select and non-select U15 male soccer players

Baseline characteristics of 31 healthy male U15 soccer players who were classified as select or non-select at the end of the season were compared. Players were 14.4 ± 0.54 years (13.6–15.3 years) at baseline; characteristics included body size, proportions and composition, estimated maturity status, several functional capacities, and coach classifications of potential in the sport. Decisions regarding selection or non-selection were made about two months after baseline. Select and non-select U15 soccer players differed significantly in estimated maturity status, body size, proportions and estimated muscle mass, functional tests related to speed, power and strength, and coach evaluation of potential, specifically tactical skills on offense and skills associated with creativity and decision making. When age and biological maturity status were statistically controlled, select and non-select players differed significantly only on the vertical jump, grip strength, and coach ratings of tactical skills on offense and of creativity and decision making. Results of stepwise discriminant analysis highlighted the importance of coach evaluation of tactical skills associated with offense, and of power and strength in distinguishing select from non-select players. The results highlight the advantages of advanced biological maturity status among adolescent male soccer players and also the importance of coach perceptions of talent. The latter implies a need for further study of the basis of coach perceptions, specifically how they are influenced by and perhaps interact with player characteristics at different ages, and how the perceptions influence playing time and player behaviors and interactions.     

The 'spiteful' origins of human cooperation

We analyse generosity, second-party ('spiteful') punishment (2PP), and third-party ('altruistic') punishment (3PP) in a cross-cultural experimental economics project. We show that smaller societies are less generous in the Dictator Game but no less prone to 2PP in the Ultimatum Game. We might assume people everywhere would be more willing to punish someone who hurt them directly (2PP) than someone who hurt an anonymous third person (3PP). While this is true of small societies, people in large societies are actually more likely to engage in 3PP than 2PP. Strong reciprocity, including generous offers and 3PP, exists mostly in large, complex societies that face numerous challenging collective action problems. We argue that 'spiteful' 2PP, motivated by the basic emotion of anger, is more universal than 3PP and sufficient to explain the origins of human cooperation.     

How reinforcer type affects choice in economic games

Behavioral economists stress that experiments on judgment and decision-making using economic games should be played with real money if the results are to have generality. Behavior analysts have sometimes disputed this contention and have reported results in which hypothetical rewards and real money have produced comparable outcomes. We review studies that have compared hypothetical and real money and discuss the results of two relevant experiments. In the first, using the Sharing Game developed in our laboratory, subjects' choices differed markedly depending on whether the rewards were real or hypothetical. In the second, using the Ultimatum and Dictator Games, we again found sharp differences between real and hypothetical rewards. However, this study also showed that time off from a tedious task could serve as a reinforcer every bit as potent as money. In addition to their empirical and theoretical contributions, these studies make the methodological point that meaningful studies may be conducted with economic games without spending money: time off from a tedious task can serve as a powerful reward.     

Currency value moderates equity preference among young children

Cooperative behavior depends in part on a preference for equitable outcomes. Recent research in behavioral economics assesses variables that influence adult concerns for equity, but few studies to date investigate the emergence of equitable behavior in children using similar economic games. We tested 288 3- to 6-year olds in an anonymous Dictator Game to assess how the value of the currency used affects equity preferences in children. To manipulate value, children played the game with their most or least favorite stickers. At all ages, we found a strong value effect with children donating more of their least favorite stickers than their favorite stickers. We also found a dramatic increase with age in the percentage of children who were prosocial (i.e. donated at least one sticker). However, children who were prosocial tended to give the same proportion of stickers at all ages – about half of their least favorite stickers and 40% of their favorite stickers. These findings highlight the influence of resource value on children's preference for equity, and provide evidence for two different processes underlying altruistic giving: the decision to donate at all and the decision about how much to donate.     

Oscillatory dynamics in evolutionary games are suppressed by heterogeneous adaptation rates of players

Game dynamics in which three or more strategies are cyclically competitive, as represented by the rock-scissors-paper game, have attracted practical and theoretical interests. In evolutionary dynamics, cyclic competition results in oscillatory dynamics of densities of individual strategists. In finite-size populations, it is known that oscillations blow up until all but one strategies are eradicated if without mutation. In the present paper, we formalize replicator dynamics with players who have different adaptation rates. We show analytically and numerically that the heterogeneous adaptation rate suppresses the oscillation amplitude. In social dilemma games with cyclically competing strategies and homogeneous adaptation rates, altruistic strategies are often relatively weak and cannot survive in finite-size populations. In such situations, heterogeneous adaptation rates save coexistence of different strategies and hence promote altruism. When one strategy dominates the others without cyclic competition, fast adaptors earn more than slow adaptors. When not, mixture of fast and slow adaptors stabilizes population dynamics, and slow adaptation does not imply inefficiency for a player.     

Is it better to give information, receive it, or be ignorant in a two-player game?

The standard approach in a biological two-player game is toassume both players choose their actions independently of oneanother, having no information about their opponent's action(simultaneous game). However, this approach is not realisticin some circumstances. In many cases, one player chooses hisaction first and then the second player chooses her action withinformation about his action (Stackelberg game). We comparethese two games, which can be mathematically analyzed into twotypes, depending on the direction of the best response function(BRF) at the evolutionarily stable strategy in the simultaneousgame (ESS_sim). We subcategorize each type of game into two cases,depending on the change in payoff to one player, when both playersare at the ESS_sim, and the other player increases his action.Our results show that in cases where the BRF is decreasing atthe ESS_sim, the first player in the Stackelberg game receivesthe highest payoff, followed by both players in the simultaneousgame, followed by the second player in the Stackelberg game.In these cases, it is best to be the first Stackelberg player.In cases where the BRF is increasing at the ESS_sim, both Stackelbergplayers receive a higher payoff than players in a simultaneousgame. In these cases, it is better for both players to playa Stackelberg game rather than a simultaneous game. However,in some cases the first Stackelberg player receives a higherpayoff than the second Stackelberg player, and in some casesthe opposite is true.     

The evolution of fairness in a biological market

Human beings universally express a concern for the fairness of social interactions, and it remains an open question that which ultimate factors led to the evolution of this preference. Here, we present a model accounting for the evolution of fairness on the basis of individual selection alone. We consider a simple social interaction based on the Dictator Game. Two individuals, a "proposer" and a "responder," have an opportunity to split a resource. When they have no choice but to interact together, the most powerful (here the proposer) reaps all the profits and fairness cannot evolve. Partner choice is the key lever to overcome this difficulty. Rather than just two individuals, we consider a population composed of two classes of individuals (either proposers or responders), and we allow the responders to choose their partner. In such a "biological market," fairness evolves as an "equilibrium price," resulting from an ecological equivalent of the law of supply and demand. If a class is disadvantaged by the chosen resource partition (i.e., if it frequently receives less than half of the resource), it is outcompeted by the other one, and automatically becomes rarer. This rarity grants it an advantage on the market, which yields in turn to the evolution of a more favorable partition. Splitting the resource into two identical halves, or more generally in a way that equalizes the payoffs of the two classes, is then the only evolutionarily stable outcome. Beyond human fairness, this mechanism also opens up new ways of explaining the distribution of benefits in many mutualistic interactions.     

Spectacular phenomena and limits to rationality in genetic and cultural evolution

In studies of both animal and human behaviour, game theory is used as a tool for understanding strategies that appear in interactions between individuals. Game theory focuses on adaptive behaviour, which can be attained only at evolutionary equilibrium. We suggest that behaviour appearing during interactions is often outside the scope of such analysis. In many types of interaction, conflicts of interest exist between players, fuelling the evolution of manipulative strategies. Such strategies evolve out of equilibrium, commonly appearing as spectacular morphology or behaviour with obscure meaning, to which other players may react in non-adaptive, irrational ways. We present a simple model to show some limitations of the game-theory approach, and outline the conditions in which evolutionary equilibria cannot be maintained. Evidence from studies of biological interactions seems to support the view that behaviour is often not at equilibrium. This also appears to be the case for many human cultural traits, which have spread rapidly despite the fact that they have a negative influence on reproduction.     

Broadened population-level frequency tuning in human auditory cortex of portable music player users

Nowadays, many people use portable players to enrich their daily life with enjoyable music. However, in noisy environments, the player volume is often set to extremely high levels in order to drown out the intense ambient noise and satisfy the appetite for music. Extensive and inappropriate usage of portable music players might cause subtle damages in the auditory system, which are not behaviorally detectable in an early stage of the hearing impairment progress. Here, by means of magnetoencephalography, we objectively examined detrimental effects of portable music player misusage on the population-level frequency tuning in the human auditory cortex. We compared two groups of young people: one group had listened to music with portable music players intensively for a long period of time, while the other group had not. Both groups performed equally and normally in standard audiological examinations (pure tone audiogram, speech test, and hearing-in-noise test). However, the objective magnetoencephalographic data demonstrated that the population-level frequency tuning in the auditory cortex of the portable music player users was significantly broadened compared to the non-users, when attention was distracted from the auditory modality; this group difference vanished when attention was directed to the auditory modality. Our conclusion is that extensive and inadequate usage of portable music players could cause subtle damages, which standard behavioral audiometric measures fail to detect in an early stage. However, these damages could lead to future irreversible hearing disorders, which would have a huge negative impact on the quality of life of those affected, and the society as a whole.     

Executive functions predict the success of top-soccer players

While the importance of physical abilities and motor coordination is non-contested in sport, more focus has recently been turned toward cognitive processes important for different sports. However, this line of studies has often investigated sport-specific cognitive traits, while few studies have focused on general cognitive traits. We explored if measures of general executive functions can predict the success of a soccer player. The present study used standardized neuropsychological assessment tools assessing players' general executive functions including on-line multi-processing such as creativity, response inhibition, and cognitive flexibility. In a first cross-sectional part of the study we compared the results between High Division players (HD), Lower Division players (LD) and a standardized norm group. The result shows that both HD and LD players had significantly better measures of executive functions in comparison to the norm group for both men and women. Moreover, the HD players outperformed the LD players in these tests. In the second prospective part of the study, a partial correlation test showed a significant correlation between the result from the executive test and the numbers of goals and assists the players had scored two seasons later. The results from this study strongly suggest that results in cognitive function tests predict the success of ball sport players.     

Self-deception in an evolutionary game

From the perspective of philosophy, the idea of humans lying to themselves seems irrational and maladaptive, if even possible. However, the paradigm of cognitive modularity admits the possibility of self-deception. Trivers argues that self-deception can increase fitness by improving the effectiveness of inter-personal deception. Ramachandran criticizes Trivers' conjecture, arguing that the costs of self-deception outweigh its benefits. We first modify a well-known cognitive modularity model of Minsky to formalize a cognitive model of self-deception. We then use Byrne's multi-dimensional dynamic character meta-model to integrate the cognitive model into an evolutionary hawk-dove game in order to investigate Trivers' and Ramachandran's conjectures. By mapping the influence of game circumstances into cognitive states, and mapping the influence of multiple cognitive modules into player decisions, our cognitive definition of self-deception is extended to a behavioral definition of self-deception. Our cognitive modules, referred to as the hunger and fear daemons, assess the benefits and the cost of competition and generate player beliefs. Daemon-assessment of encounter benefits and costs may lead to inter-daemonic conflict, that is, ambivalence, about whether or not to fight. Player-types vary in the manner by which such inter-daemonic conflict is resolved, and varieties of self-deception are modeled as type-specific conflict-resolution mechanisms. In the display phase of the game, players signal to one another and update their beliefs before finally committing to a decision (hawk or dove). Self-deception can affect player beliefs, and hence player actions, before or after signaling. In support of Trivers' conjecture, the self-deceiving types do outperform the non-self-deceiving type. We analyse the sensitivity of this result to parameters of the cognitive model, specifically the cognitive resolution of the players and the influence of player signals on co-player beliefs.