The reputation of punishers

Punishment is a potential mechanism to stabilise cooperation between self-regarding agents. Theoretical and empirical studies on the importance of a punitive reputation have yielded conflicting results. Here, we propose that a variety of factors interact to explain why a punitive reputation is sometimes beneficial and sometimes harmful. We predict that benefits are most likely to occur in forced play scenarios and in situations where punishment is the only means to convey an individual's cooperative intent and willingness to uphold fairness norms. By contrast, if partner choice is possible and an individual's cooperative intent can be inferred directly, then individuals with a nonpunishing cooperative reputation should typically be preferred over punishing cooperators

Exploring the trade-off between quality and fairness in human partner choice

Partner choice is an important force underpinning cooperation in humans and other animals. Nevertheless, the mechanisms individuals use to evaluate and discriminate among partners who vary across different dimensions are poorly understood. Generally, individuals are expected to prefer partners who are both able and willing to invest in cooperation but how do individuals prioritize the ability over willingness to invest when these characteristics are opposed to one another? We used a modified Dictator Game to tackle this question. Choosers evaluated partners varying in quality (proxied by wealth) and fairness, in conditions when wealth was relatively stable or liable to change. When both partners were equally fair (or unfair), choosers typically preferred the richer partner. Nevertheless, when asked to choose between a rich-stingy and a poor-fair partner, choosers prioritized fairness over wealth—with this preference being particularly pronounced when wealth was unstable. The implications of these findings for real-world partner choice are discussed

Conflict and cooperation in paranoia: a large-scale behavioural experiment

BACKGROUND: Paranoia involves thoughts and beliefs about the harmful intent of others but the social consequences have been much less studied. We investigated whether paranoia predicts maladaptive social behaviour in terms of cooperative and punitive behaviour using experimental game theory paradigms, and examined whether reduced cooperation is best explained in terms of distrust as previous studies have claimed. METHODS: We recruited a large population sample (N = 2132) online. All participants completed the Green et al. Paranoid Thoughts Scale and (i) a Dictator Game and (ii) an Ultimatum Game, the former with an option for costly punishment. Following distrust-based accounts, we predicted highly paranoid people would make higher offers when the outcome depended on receiving a positive response from their partner (Ultimatum Game) but no difference when the partner's response was irrelevant (Dictator Game). We also predicted paranoia would increase punitive responses. Predictions were pre-registered in advance of data collection. Data and materials are open access. RESULTS: Highly paranoid participants actually made lower offers than non-paranoid participants both in the Dictator Game and in the Ultimatum Game. Paranoia positively predicted punitive responses. CONCLUSIONS: These findings suggest that distrust is not the best explanation for reduced cooperation in paranoia and alternative explanations, such as increased self-interest, may apply. However, the tendency to attribute harmful intent to partners was important in motivating punitive responses. These results highlight differing motivations underlying adverse social behaviour in paranoia and suggest that accounts based solely on the presenting features of paranoia may need to be rethought

Supporting Conservation: The Roles of Flagship Species and Identifiable Victims

Psychological insights into human behaviour can have enormous applied value for promoting charitable giving. Nevertheless, the application of these insights to conservation appeals featuring non-human animals has scarcely been explored. Although people often donate more when presented with single 'identifiable' victims, whether this effect also extends to non-humans is not known. Similarly, although many conservation appeals feature flagship species, it is unclear whether flagship species generate increased donations. We experimentally investigated how (i) identifiable versus statistical beneficiaries and (ii) flagship versus non-flagship species affected donations to a conservation charity. Unexpectedly, subjects did not donate more when presented with single identifiable beneficiaries rather than groups of beneficiaries. Flagship species, on the other hand, increased donation amounts relative to appeals featuring non-flagship species. We discuss how these findings can inform and improve the effectiveness of conservation fundraising appeals

Exploring the Motivations for Punishment: Framing and Country-Level Effects

Identifying the motives underpinning punishment is crucial for understanding its evolved function. In principle, punishment of distributional inequality could be motivated by the desire to reciprocate losses ('revenge') or by the desire to reduce payoff asymmetries between the punisher and the target ('inequality aversion'). By separating these two possible motivations, recent work suggests that punishment is more likely to be motivated by disadvantageous inequality aversion than by a desire for revenge. Nevertheless, these findings have not consistently replicated across different studies. Here, we suggest that considering country of origin—previously overlooked as a possible source of variation in responses—is important for understanding when and why individuals punish one another. We conducted a two-player stealing game with punishment, using data from 2,400 subjects recruited from the USA and India. US-based subjects punished in response to losses and disadvantageous inequality, but seldom invested in antisocial punishment (defined here as punishment of non-stealing partners). India-based subjects, on the other hand, punished at higher levels than US-based subjects and, so long as they did not experience disadvantageous inequality, punished stealing and non-stealing partners indiscriminately. Nevertheless, as in the USA, when stealing resulted in disadvantageous inequality, India-based subjects punished stealing partners more than non-stealing partners. These results are consistent with the hypothesis that variation in punitive behavior varies across societies, and support the idea that punishment might sometimes function to improve relative status, rather than to enforce cooperation

Third-party punishers do not compete to be chosen as partners in an experimental game

Third-party punishment is thought to act as an honest signal of cooperative intent and such signals might escalate when competing to be chosen as a partner. Here, we investigate whether partner choice competition prompts escalating investment in third-party punishment. We also consider the case of signalling via helpful acts to provide a direct test of the relative strength of the two types of signals. Individuals invested more in third-party helping than third-party punishment and invested more in both signals when observed compared to when investments would be unseen. We found no clear effect of partner choice (over and above mere observation) on investments in either punishment or helping. Third-parties who invested more than a partner were preferentially chosen for a subsequent Trust Game although the preference to interact with the higher investor was more pronounced in the help than in the punishment condition. Third-parties who invested more were entrusted with more money and investments in third-party punishment or helping reliably signalled trustworthiness. Individuals who did not invest in third-party helping were more likely to be untrustworthy than those who did not invest in third-party punishment. This supports the conception of punishment as a more ambiguous signal of cooperative intent compared to help

Dictator Game Giving: The Importance of Descriptive versus Injunctive Norms.

Human behaviour is influenced by social norms but norms can entail two types of information. Descriptive norms refer to what others do in this context, while injunctive norms refer to what ought to be done to ensure social approval. In many real-world situations these norms are often presented concurrently meaning that their independent effects on behaviour are difficult to establish. Here we used an online Dictator Game to test how descriptive and injunctive norms would influence dictator donations when presented independently of one another. In addition, we varied the cost of complying with the norm: By stating that $0.20 or$0.50 cent donations from a $1 stake were normal or suggested, respectively. Specifying a higher target amount was associated with increased mean donation size. In contrast to previous studies, descriptive norms did not seem to influence giving behaviour in this context, whereas injunctive norms were associated with increased likelihood to give at least the target amount to the partner. This raises the question of whether injunctive norms might be more effective than descriptive norms at promoting prosocial behaviour in other settings

Power asymmetries and punishment in a prisoner's dilemma with variable cooperative investment

In many two-player games, players that invest in punishment finish with lower payoffs than those who abstain from punishing. These results question the effectiveness of punishment at promoting cooperation, especially when retaliation is possible. It has been suggested that these findings may stem from the unrealistic assumption that all players are equal in terms of power. However, a previous empirical study which incorporated power asymmetries into an iterated prisoner's dilemma (IPD) game failed to show that power asymmetries stabilize cooperation when punishment is possible. Instead, players cooperated in response to their partner cooperating, and punishment did not yield any additional increase in tendency to cooperate. Nevertheless, this previous study only allowed an all-or-nothing–rather than a variable–cooperation investment. It is possible that power asymmetries increase the effectiveness of punishment from strong players only when players are able to vary their investment in cooperation. We tested this hypothesis using a modified IPD game which allowed players to vary their investment in cooperation in response to being punished. As in the previous study, punishment from strong players did not increase cooperation under any circumstances. Thus, in two-player games with symmetric strategy sets, punishment does not appear to increase cooperation

Human punishment is motivated by both a desire for revenge and a desire for equality

Humans willingly pay a cost to punish defecting partners in experimental games. However, the psychological motives underpinning punishment are unclear. Punishment could stem from the desire to reciprocally harm a cheat (i.e. revenge) which is arguably indicative of a deterrent function. Alternatively, punishment could be motivated by the desire to redress the balance between punisher and cheat. Such a desire for equality might be more indicative of a fitness-leveling function. We used a two player experimental game to disentangle these two possibilities. In this game, one player could choose to steal $0.20 from their partner. Depending on the treatment, players interacting with a stealing partner experienced either advantageous inequality, equal outcomes or disadvantageous inequality. Players could punish stealing partners, but some players had access to effective punishment (1:3 fee to fine) whereas others could only use ineffective punishment (1:1). Players who had access to effective punishment could reduce disadvantageous inequality by tailoring their investment in punishment whereas ineffective punishment did not change the relative payoffs of the individuals in the game but could be used to exact revenge. Players punished regardless of whether stealing created outcome inequality or whether punishment was ineffective at removing payoff differentials, suggesting that punishment was at least partly motivated by the desire to inflict reciprocal harm. However, in the effective punishment condition, players' tendency to punish increased if stealing resulted in disadvantageous inequality and, when possible, punishers tailored their investment in punishment to create equal outcomes. Together these findings suggest that punishment is motivated by both a desire for revenge and a desire for equality. The implications of these findings are discussed