Voluntary restrictions on self-reliance increase cooperation and mitigate wealth inequality

An outside individual option increases optimism and facilitates collaboration when groups form flexibly

Voluntary participation is a central yet understudied aspect of collaboration. Here, we model collaboration as people's voluntary choices between joining an uncertain public goods provisioning in groups and pursuing a less profitable but certain individual option. First, we find that voluntariness in collaboration increases the likelihood of group success via two pathways, both contributing to form more optimistic groups: pessimistic defectors are filtered out from groups, and some individuals update their beliefs to become cooperative. Second, we reconcile these findings with existing literature that highlights the detrimental effects of an individual option. We argue that the impact of an outside individual option on collaboration depends on the "externality" of loners - the influence that those leaving the group still exert on group endeavors. Theoretically and experimentally, we show that if collaboration allows for flexible group formation, the negative externality of loners remains limited, and the presence of an individual option robustly aids collaborative success.

Group Formation and the Evolution of Human Social Organization

Humans operate in groups that are oftentimes nested in multilayered collectives such as work units within departments and companies, neighborhoods within cities, and regions within nation states. With psychological science mostly focusing on proximate reasons for individuals to join existing groups and how existing groups function, we still poorly understand why groups form ex nihilo, how groups evolve into complex multilayered social structures, and what explains fission-fusion dynamics. Here we address group formation and the evolution of social organization at both the proximate and ultimate level of analysis. Building on models of fitness interdependence and cooperation, we propose that socioecologies can create positive interdependencies among strangers and pave the way for the formation of stable coalitions and groups through reciprocity and reputation-based partner selection. Such groups are marked by in-group bounded, parochial cooperation together with an array of social institutions for managing the commons, allowing groups to scale in size and complexity while avoiding the breakdown of cooperation. Our analysis reveals how distinct group cultures can endogenously emerge from reciprocal cooperation, shows that social identification and group commitment are likely consequences rather than causes of group cooperation, and explains when intergroup relations gravitate toward peaceful coexistence, integration, or conflict.

Explaining inequality tolerance in the lab: effects of political efficacy and prospects of mobility on collective demand for redistribution

The low public demand for redistribution despite growing economic inequality has been characterized as a paradox especially for disadvantaged individuals. One prominent explanation for people's tolerance to growing inequality posits that increased optimism about prospects of upward mobility undermines support for redistribution. A less explored explanation postulates that low political efficacy of disadvantaged individuals to enact meaningful change erodes collective demand for redistribution. In two preregistered experiments, we create a dynamic environment where low-income individuals collectively demand income redistribution by contributing to a public pool (collective action strategy), compete with each other for high-income group positions (individual mobility strategy), or avoid risks and disengage from both strategies (social inaction strategy). Lack of political efficacy, operationalized as high redistribution thresholds, gradually curtailed collective action, while exposure to high prospects of mobility did not influence collective action even when income group boundaries were highly permeable. Across participants, we identified three behavioral types (i.e., "mobility seekers", "egalitarians", and "disillusioned") whose prevalence was affected by political efficacy but not by prospects of mobility or actual group permeability. These results cast doubt on the universality of the prospects of mobility hypothesis and highlight the prominent role of political inequality in the perpetuation of economic inequality.

Inferences about interdependence shape cooperation

During social interactions in daily life, people possess imperfect knowledge of their interdependence (i.e., how behaviors affect each person's outcomes), and what people infer about their interdependence can shape their behaviors. We review theory and research that suggests people can infer their interdependence with others along several dimensions, including mutual dependence, power, and corresponding-versus-conflicting interests. We discuss how perceptions of interdependence affect how people cooperate and punish others' defection in everyday life. We propose that people understand their interdependence with others through knowledge of the action space, cues during social interactions (e.g., partner behaviors), and priors based on experience. Finally, we describe how learning interdependence could occur through domain-specific and domain-general mechanisms.

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.

Climate policy support as a tool to control others' (but not own) environmental behavior?

Drastic reductions in greenhouse gas emissions are necessary to successfully mitigate climate change. Individual environmental behavior is central to this change. Given that environmental behavior necessitates 1) effortful individual self-control and 2) cooperation by others, public policy may constitute an attractive instrument for regulating one's own as well as others' environmental behavior. Framing climate change mitigation as a cooperative self-control problem, we explore the incremental predictive power of self-control and beliefs surrounding others' cooperation beyond established predictors of policy support in study 1 using machine-learning (N = 610). In study 2, we systematically test and confirm the effects of self-control and beliefs surrounding others' cooperation (N = 270). Both studies showed that personal importance of climate change mitigation and perceived insufficiency of others' environmental behavior predict policy support, while there was no strong evidence for a negative association between own-self control success and policy support. These results emerge beyond the effects of established predictors, such as environmental attitudes and beliefs, risk perception (study 1), and social norms (study 2). Results are discussed in terms of leveraging policy as a behavioral enactment constraint to control others' but not own environmental behavior.