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).

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).

Political ideology and moral dilemmas in public good provision.

Individuals often face dilemmas in which non-cooperation serves their self-interest and cooperation favors society at large. Cooperation is often considered the moral choice because it creates equality and fairness among citizens. Accordingly, individuals whose political ideology attaches greater value to equality than to agency and self-reliance should not only cooperate on more rather than less efficient public goods, but also more on public goods from which individuals benefit equally rather than unequally. We examine this possibility by comparing ideologically left-leaning and right-leaning individuals' cooperation on multiple public goods that varied in efficiency and (in)equality in returns. We find that left-leaning individuals cooperate more than right-leaning ones, but only on public goods that benefit everyone equally, and not more on public goods that generate inequalities. Left-leaning individuals also trust and expect others to cooperate more on equal- versus unequal-returns public goods, while self-identified right-leaning individuals do not differentiate between these. Interestingly, ideology does not predict which public good is deemed more morally appropriate to cooperate on. Results combined specify when and why self-identified leftists can(not) be expected to cooperate more than rightists and reveal how moral decision-making depends on structural elements of the public good provision problems that citizens face.

The evolution of universal cooperation.

Humans work together in groups to tackle shared problems and contribute to local club goods that benefit other group members. Whereas benefits from club goods remain group bound, groups are often nested in overarching collectives that face shared problems like pandemics or climate change. Such challenges require individuals to cooperate across group boundaries, raising the question how cooperation can transcend beyond confined groups. Here, we show how frequent intergroup interactions allow groups to transition from group-bound to universal cooperation. With frequent intergroup interactions, reciprocity of cooperative acts permeates group boundaries and enables the evolution of universal cooperation. As soon as intergroup interactions take place frequently, people start to selectively reward cooperation aimed at benefitting everyone, irrespective of their group membership. Simulations further show that it becomes more difficult to overcome group-bound cooperation when populations are fragmented into many small groups. Our findings reveal important prerequisites for the evolution of universal cooperation.