Cooperation and social organization depend on weighing private and public reputations.

To avoid exploitation by defectors, people can use past experiences with others when deciding to cooperate or not ('private information'). Alternatively, people can derive others' reputation from 'public' information provided by individuals within the social network. However, public information may be aligned or misaligned with one's own private experiences and different individuals, such as 'friends' and 'enemies', may have different opinions about the reputation of others. Using evolutionary agent-based simulations, we examine how cooperation and social organization is shaped when agents (1) prioritize private or public information about others' reputation, and (2) integrate others' opinions using a friend-focused or a friend-and-enemy focused heuristic (relying on reputation information from only friends or also enemies, respectively). When agents prioritize public information and rely on friend-and-enemy heuristics, we observe polarization cycles marked by high cooperation, invasion by defectors, and subsequent population fragmentation. Prioritizing private information diminishes polarization and defector invasions, but also results in limited cooperation. Only when using friend-focused heuristics and following past experiences or the recommendation of friends create prosperous and stable populations based on cooperation. These results show how combining one's own experiences and the opinions of friends can lead to stable and large-scale cooperation and highlight the important role of following the advice of friends in the evolution of group cooperation.

The nasty neighbor effect in humans.

Like other group-living species, humans often cooperate more with an in-group member than with out-group members and strangers. Greater in-group favoritism should imply that people also compete less with in-group members than with out-group members and strangers. However, in situations where people could invest to take other's resources and invest to protect against exploitation, we observed the opposite. Akin to what in other species is known as the "nasty neighbor effect," people invested more when facing an in-group rather than out-group member or stranger across 51 nations, in different communities in Kenya, and in representative samples from the United Kingdom. This "nasty neighbor" behavior is independent of in-group favoritism in trust and emerges when people perceive within-group resource scarcity. We discuss how to reconcile that humans exhibit nastiness and favoritism toward in-group members with existing theory on in-group favoritism.

Distinct neurocognitive pathways underlying creativity: An integrative approach.

By examining the shared neuro-cognitive correlates of curiosity and creativity, we better understand the brain basis of creativity. However, by only examining shared components, important neuro-cognitive correlates are overlooked. Here, we argue that any comprehensive brain model of creativity should consider multiple cognitive processes and, alongside the interplay between brain networks, also the neurochemistry and neural oscillations that underly creativity.

Equality and efficiency shape cooperation in multiple-public-goods provision problems.

The functioning of groups and societies requires that individuals cooperate on public goods such as healthcare and state defense. More often than not, individuals face multiple public goods and must choose on which to cooperate, if at all. Such decisions can be difficult when public goods are attractive on one dimension (e.g., being "efficient" in providing comparatively high returns) and unattractive on another (e.g., creating inequality by providing some group members greater returns than others). We examined how people manage such decision conflicts in five preregistered experiments (N = 900) that confronted participants with two public goods that varied in efficiency and (in)equality of returns. People cooperated more on the comparatively efficient public good and on the equal-return (vs. unequal-return) public good (Experiment 1), yet when the unequal-returns public good was also the most efficient, individuals cooperated comparatively more on this unequal-but-efficient public good when they themselves benefitted the most from inequality (Experiments 2-4). Low beneficiaries largely ignored public goods efficiency and preferentially cooperated on the equal- rather than unequal-returns public good. Expectations (Experiments 2-4), preferences for revising the multiple-public-goods provision problems' choice architecture (Experiments 3-4), and descriptive norms held by uninvolved arbitrators (Experiment 5) echoed these cooperation patterns, but uninvolved arbitrators deemed it socially appropriate to cooperate more on the equal than the unequal public good regardless of beneficiary position. We discuss implications for theory and policy on cooperation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

On being unpredictable and winning.

In theory, it can be strategically advantageous for competitors to make themselves unpredictable to their opponents, for example, by variably mixing hostility and friendliness. Empirically, it remains open whether and how competitors make themselves unpredictable, why they do so, and how this conditions conflict dynamics and outcomes. We examine these questions in interactive attacker-defender contests, in which attackers invest to capture resources held and defended by their opponent. Study 1, a reanalysis of nine (un)published experiments (total N = 650), reveals significant cross-trial variability especially in proactive attacks and less in reactive defense. Study 2 (N = 200) shows that greater variability makes both attacker's and defender's next move more difficult to predict, especially when variability is due to occasional rather than (in)frequent extreme investments in conflict. Studies 3 (N = 27) and 4 (N = 106) show that precontest testosterone, a hormone associated with risk-taking and status competition, drives variability during attack which, in turn, increases sympathetic arousal in defenders and defender variability (Study 4). Rather than being motivated by wealth maximization, being unpredictable in conflict and competition emerges in function of the attacker's desire to win "no matter what" and comes with significant welfare cost to both victor and victim. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Peace as prerequisite rather than consequence of cooperation.

We take issue with Glowacki's assumption that intergroup relations are characterized by positive-sum interactions and suggest to include negative-sum interactions, and between-group independence. As such, peace may be better defined as the absence of negative-sum interactions. Rather than being a consequence of cooperation, peace emerges as a necessary but not sufficient prerequisite for positive (in)direct reciprocity between groups that, in turn, is key to social identities and cultural complexity.