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The target article offers a game-theoretical analysis of primitive intergroup aggression (i.e., raiding) and discusses difficulties in achieving peace. We argue the analysis does not capture the actual strategy space, missing out “do-nothing.” Experimental evidence robustly shows people prefer doing nothing against out-group members over cooperating with/attacking them. Thus, the target article overestimates the likelihood of intergroup aggression.

While negative gossip serves important functions for groups, previous studies have revealed that individuals negatively evaluate negative gossipers. Given the ubiquity of gossip, there should be conditions under which negative gossipers get away with negative evaluations. In our study (N = 386), we tested the hypothesis that individuals evaluate ingroup negative gossipers more leniently than outgroup negative gossipers and that those high in social anxiety evaluate negative gossipers more negatively than those low in social anxiety, potentially regardless of the group membership of negative gossipers. We found that individuals liked and evaluated negative gossipers less and less favourably than non-gossipers regardless of their group membership, inconsistently with our hypothesis. Contrary to our hypothesis, we found that individuals high in social anxiety liked and evaluated negative gossipers more and more favourably than those low in social anxiety.

Indirect reciprocity is a reputation-based mechanism proposed to explain the evolution of human cooperation. Theoretical models demonstrated that the use of both first-order information (i.e., whether an evaluation target cooperated) and second-order information (i.e. the reputation of an interaction partner of the evaluation target) is critical for the evolution of cooperation. However, empirical findings on the use of second-order information have been mixed. Drawing upon the literature on group-bounded indirect reciprocity, we tested the hypothesis that individuals would be more sensitive to second-order information when evaluating ingroup interactions, compared to when evaluating outgroup interactions. We conducted a preregistered online experiment (N = 604), where we independently manipulated group membership (ingroup vs. outgroup), target behaviour (cooperation vs. defection), and recipient reputation (good vs. bad). We found that donors who defected against good recipients were rated more negatively than those who defected against bad recipients, indicating the use of second-order information. Partly consistently with our hypothesis, when individuals evaluated coopering donors, second-order information influenced reputation for ingroup donor-recipient interactions more than for outgroup donor-recipient interactions. Nevertheless, individuals readily used second-order information, whether or not they evaluated ingroup or outgroup donor-recipient interactions.

Previous studies on psychological adaptations to pathogen threats revealed the link between pathogen psychology and group behavior, especially in-group-oriented mindsets such as conformity, and the endorsement of group binding moral values. The relationship between behavioral immune responses and in-group attitudes has been mostly discussed in relation to the adaptive strategy to avoid pathogens. Yet, there is the other side of the behavioral immune system: reactive defense against pathogens (e.g., soliciting social support from others). By operationally defining in-group-oriented mindsets as the endorsement of group binding moral values, we explored how the tendencies to avoid diseases and minimize the negative influences of contracted diseases were each related to in-group-oriented mindsets in two countries (Study 1: the UK, N  = 645; Study 2: Japan, N  = 651). We found that the endorsement of group binding moral values was robustly associated with the latter but not with the former, suggesting that the reactive side of pathogen psychology may play an important role in shaping in-group-oriented mindsets.

Audience cost theory suggests that as a country increases its audience costs, it can send a credible threat to an opponent and prevail in an international crisis. Many experimental studies show that domestic citizens of a challenger state disapprove of a leader who backs down in a crisis, which constitutes evidence for audience costs. However, what about the audience’s perception in the target country? Even if audience costs emerge in a threatening country, audiences in its adversary may not recognize this. If that is the case, audience costs do not function as costly signals. Additionally, the challenger’s regime type may play an important role in how people perceive the emergence of audience costs. Our pre-registered survey experiment in the United States (N = 1404) finds that audiences in a target state correctly perceive the emergence of audience costs in a challenger state. However, we also find that the magnitude of perceived audience costs or threat credibility does not differ between a democratic and a dictatorial challenger. These findings suggest that leaders of both democratic and autocratic regimes can effectively tie their hands by increasing domestic audience costs.

The emergence of COVID-19 dramatically changed social behavior across societies and contexts. Here we study whether social norms also changed. Specifically, we study this question for cultural tightness (the degree to which societies generally have strong norms), specific social norms (e.g. stealing, hand washing), and norms about enforcement, using survey data from 30,431 respondents in 43 countries recorded before and in the early stages following the emergence of COVID-19. Using variation in disease intensity, we shed light on the mechanisms predicting changes in social norm measures. We find evidence that, after the emergence of the COVID-19 pandemic, hand washing norms increased while tightness and punishing frequency slightly decreased but observe no evidence for a robust change in most other norms. Thus, at least in the short term, our findings suggest that cultures are largely stable to pandemic threats except in those norms, hand washing in this case, that are perceived to be directly relevant to dealing with the collective threat. Tightness-looseness theory predicts that social norms strengthen following threat. Here the authors test this and find that, after the emergence of the COVID-19 pandemic, hand washing norms increased, but no evidence was observed for a robust change in most other norms.

When someone violates a social norm, others may think that some sanction would be appropriate. We examine how the experience of emotions like anger and disgust relate to the judged appropriateness of sanctions, in a pre-registered analysis of data from a large-scale study in 56 societies. Across the world, we find that individuals who experience anger and disgust over a norm violation are more likely to endorse confrontation, ostracism and, to a smaller extent, gossip. Moreover, we find that the experience of anger is consistently the strongest predictor of judgments of confrontation, compared to other emotions. Although the link between state-based emotions and judgments may seem universal, its strength varies across countries. Aligned with theoretical predictions, this link is stronger in societies, and among individuals, that place higher value on individual autonomy. Thus, autonomy values may increase the role that emotions play in guiding judgments of social sanctions.

Issues related to sustainability (e.g., climate change and over-fishing) often manifest themselves as intergenerational social dilemmas, where people are faced with a choice between self-serving, unsustainable behavior and sustainable, personally costly behavior. Extending the previous literature on (non-intergenerational) intergroup cooperation, we tested whether group membership of the future generations influenced sustainable decision-making. In two preregistered studies using the intergenerational sustainability dilemma game, we found that individuals were more likely to make a sustainable (vs. selfish) decision when they believed that their current behavior would benefit future ingroup members, whereas more selfish decisions were made when benefits would accrue to outgroup members. These findings held in both the minimal group (Study 1: N = 1393) and national group (Study 2: Japan vs. China, N = 1781) contexts. The effect of ingroup intergenerational membership on cooperation was mediated by higher felt responsibility for future generations in both minimal and national group contexts. The effect of outgroup membership on intergenerational cooperation was mediated by a reduced sense of reputational concern in the minimal group context and by reduced affinity, legacy motivation, and responsibility for future generations in the nationality context. Two experimental studies using the intergenerational sustainable dilemma game found that people made more sustainable choices when future beneficiaries were ingroup members, and less when they were outgroup members.

Norton et al., 2007, demonstrated a counterintuitive phenomenon that knowing other people better and/or having more information about them is associated with decreased liking. They summarized it as ambiguity leads to liking, whereas familiarity can breed contempt. In a Registered Report with a US Prolific undergraduate student sample (N = 801), we directly replicated Studies 1a, 1b and 2 and conceptually replicated Studies 3 and 4 from Norton et al., 2007. Extending their research, we also proposed that curiosity provides an alternative path to liking, hypothesizing that curiosity mediates the relationship between knowledge and liking. Overall, we found weak support for the original findings. Consistent with the original article, participants believed they would like someone who they knew more about (original: h = 0.52-0.70; replication: h = 0.55-0.75) and that knowledge positively predicts liking (original: h = 0.21-0.45; replication: h = 0.57-0.76). However, we found no indication of the number of traits known influencing liking (original: r = -0.43 to -0.005; replication: r = -0.05 to 0.06) or perceived similarity to the target (d = 0.00), for a mediating effect of perceived similarity, for a dissimilarity cascade effect, or for changes in liking or perceived similarity as a factor of learning more about the target. In our extensions, we found support for a positive relationship between curiosity and liking (r = 0.62-0.70), but not for knowledge and curiosity (r = -0.06 to 0.05). Overall, our findings suggest that learning more about others may not influence perceptions of liking, similarity or curiosity towards them. Materials, data and code are available on https://osf.io/j6tqr/. This Registered Report has been officially endorsed by Peer Community in Registered Reports: https://doi.org/10.24072/pci.rr.100947.Norton et al., 2007, demonstrated a counterintuitive phenomenon that knowing other people better and/or having more information about them is associated with decreased liking. They summarized it as ambiguity leads to liking, whereas familiarity can breed contempt. In a Registered Report with a US Prolific undergraduate student sample (N = 801), we directly replicated Studies 1a, 1b and 2 and conceptually replicated Studies 3 and 4 from Norton et al., 2007. Extending their research, we also proposed that curiosity provides an alternative path to liking, hypothesizing that curiosity mediates the relationship between knowledge and liking. Overall, we found weak support for the original findings. Consistent with the original article, participants believed they would like someone who they knew more about (original: h = 0.52-0.70; replication: h = 0.55-0.75) and that knowledge positively predicts liking (original: h = 0.21-0.45; replication: h = 0.57-0.76). However, we found no indication of the number of traits known influencing liking (original: r = -0.43 to -0.005; replication: r = -0.05 to 0.06) or perceived similarity to the target (d = 0.00), for a mediating effect of perceived similarity, for a dissimilarity cascade effect, or for changes in liking or perceived similarity as a factor of learning more about the target. In our extensions, we found support for a positive relationship between curiosity and liking (r = 0.62-0.70), but not for knowledge and curiosity (r = -0.06 to 0.05). Overall, our findings suggest that learning more about others may not influence perceptions of liking, similarity or curiosity towards them. Materials, data and code are available on https://osf.io/j6tqr/. This Registered Report has been officially endorsed by Peer Community in Registered Reports: https://doi.org/10.24072/pci.rr.100947.