Search

We appreciate Barrett’s (2011, this issue) comments and her discussion of how our two-stage model is and is not consistent with Darwin’s views on the evolution of emotion expressions. Like many pioneering books, Darwin’s The Expression of Emotions in Man and Animals represents a flurry of novel and revolutionary, yet often inconsistent, ideas, which lend themselves to different readings. However, while the historical perspective Barrett provides is useful, the scientific conversation on emotion expressions has evolved since Darwin. Here, we briefly discuss why the two alternative explanations Barrett offers for the origins of emotion expressions—expressions as cultural symbols and/or as evolutionary byproducts—are both untenable in light of existing research. We also note that although evidence for our two-stage model is currently incomplete, our goal was not to tell a complete story. Instead, we sought to offer the best emerging explanation for the existing research and provide a path for future empirical work that can test it. [ABSTRACT FROM PUBLISHER]

We develop a cultural evolutionary theory of the origins of prosocial religions and apply it to resolve two puzzles in human psychology and cultural history: (1) the rise of large-scale cooperation among strangers and, simultaneously, (2) the spread of prosocial religions in the last 10–12 millennia. We argue that these two developments were importantly linked and mutually energizing. We explain how a package of culturally evolved religious beliefs and practices characterized by increasingly potent, moralizing, supernatural agents, credible displays of faith, and other psychologically active elements conducive to social solidarity promoted high fertility rates and large-scale cooperation with co-religionists, often contributing to success in intergroup competition and conflict. In turn, prosocial religious beliefs and practices spread and aggregated as these successful groups expanded, or were copied by less successful groups. This synthesis is grounded in the idea that although religious beliefs and practices originally arose as nonadaptive by-products of innate cognitive functions, particular cultural variants were then selected for their prosocial effects in a long-term, cultural evolutionary process. This framework (1) reconciles key aspects of the adaptationist and by-product approaches to the origins of religion, (2) explains a variety of empirical observations that have not received adequate attention, and (3) generates novel predictions. Converging lines of evidence drawn from diverse disciplines provide empirical support while at the same time encouraging new research directions and opening up new questions for exploration and debate. [ABSTRACT FROM AUTHOR]

We extend the target authors' moral disciplining theory (MDT) by discussing signaling, proscriptive and prescriptive morality, and the dynamics by which signaling may operate in tandem with proscriptive and prescriptive forms of moral disciplining. We also suggest that MDT can help explain challenges to economic and social progress by revealing fundamental tensions between puritanical intuitions and liberal ideals. [ABSTRACT FROM AUTHOR]

People believe that effort is valuable, but what kind of value does it confer? We find that displays of effort signal moral character. Eight studies (N = 5,502) demonstrate the nature of these effects in the domains of paid employment, personal fitness, and charitable fundraising. The exertion of effort is deemed morally admirable (Studies 1-6) and is monetarily rewarded (Studies 2-6), even in situations where effort does not directly generate additional product, quality, or economic value. Convergent patterns of results emerged in South Korean and French cross-cultural replications (Studies 2b and 2c). We contend that the seeming irrationality of valuing effort for its own sake, such as in situations where one's efforts do not directly increase economic output (Studies 3-6), reveals a "deeply rational" social heuristic for evaluating potential cooperation partners. Specifically, effort cues engender broad moral trait ascriptions, and this moralization of effort influences donation behaviors (Study 5) and cooperative partner choice decision-making (Studies 4 and 6). In situating our account of effort moralization into past research and theorizing, we also consider the implications of these effects for social welfare policy and the future of work. [ABSTRACT FROM AUTHOR]

Belief in free will is a pervasive phenomenon that has important consequences for prosocial actions and punitive judgments, but little research has investigated why free will beliefs are so widespread. Across 5 studies using experimental, survey, and archival data and multiple measures of free will belief, we tested the hypothesis that a key factor promoting belief in free will is a fundamental desire to hold others morally responsible for their wrongful behaviors. In Study 1, participants reported greater belief in free will after considering an immoral action than a morally neutral one. Study 2 provided evidence that this effect was due to heightened punitive motivations. In a field experiment (Study 3), an ostensibly real classroom cheating incident led to increased free will beliefs, again due to heightened punitive motivations. In Study 4, reading about others' immoral behaviors reduced the perceived merit of anti-free-will research, thus demonstrating the effect with an indirect measure of free will belief. Finally, Study 5 examined this relationship outside the laboratory and found that the real-world prevalence of immoral behavior (as measured by crime and homicide rates) predicted free will belief on a country level. Taken together, these results provide a potential explanation for the strength and prevalence of belief in free will: It is functional for holding others morally responsible and facilitates justifiably punishing harmful members of society. [ABSTRACT FROM AUTHOR]

In 14 studies, we tested whether political conservatives' stronger free will beliefs were linked to stronger and broader tendencies to moralize and, thus, a greater motivation to assign blame. In Study 1 (meta-analysis of 5 studies, n = 308,499) we show that conservatives have stronger tendencies to moralize than liberals, even for moralization measures containing zero political content (e.g., moral badness ratings of faces and personality traits). In Study 2, we show that conservatives report higher free will belief, and this is statistically mediated by the belief that people should be held morally responsible for their bad behavior (n = 14,707). In Study 3, we show that political conservatism is associated with higher attributions of free will for specific events. Turning to experimental manipulations to test our hypotheses, we show the following: when conservatives and liberals see an action as equally wrong there is no difference in free will attributions (Study 4); when conservatives see an action as less wrong than liberals, they attribute less free will (Study 5); and specific perceptions of wrongness account for the relation between political ideology and free will attributions (Study 6a and 6b). Finally, we show that political conservatives and liberals even differentially attribute free will for the same action depending on who performed it (Studies 7a–d). These results are consistent with our theory that political differences in free will belief are at least partly explicable by conservatives' tendency to moralize, which strengthens motivation to justify blame with stronger belief in free will and personal accountability. [ABSTRACT FROM AUTHOR]

Many scholars have argued that religion reduces violent behavior within human social groups. Here, we tested whether intelligence moderates this relationship. We hypothesized that religion would have greater utility for regulating violent behavior among societies with relatively lower average IQs than among societies with relatively more cognitively gifted citizens. Two studies supported this hypothesis. Study 1, a longitudinal analysis from 1945 to 2010 (with up to 176 countries and 1,046 observations), demonstrated that declines in religiosity were associated with increases in homicide rates—but only in countries with relatively low average IQs. Study 2, a multiverse analysis (171 models) using modern data (97–195 countries) and various controls, consistently confirmed that lower rates of religiosity were more strongly associated with higher homicide rates in countries with lower average IQ. These findings raise questions about how secularization might differentially affect groups of different mean cognitive ability. [ABSTRACT FROM AUTHOR]

Four experiments (total N = 3591) examined how thinking about Karma and God increases adherence to social norms that prescribe fairness in anonymous dictator games. We found that (1) thinking about Karma decreased selfishness among karmic believers across religious affiliations, including Hindus, Buddhists, Christians, and non-religious Americans; (2) thinking about God also decreased selfishness among believers in God (but not among non-believers), replicating previous findings; and (3) thinking about both karma and God shifted participants' initially-selfish offers towards fairness (the normatively prosocial response), but had no effect on already fair offers. These supernatural framing effects were obtained and replicated in high-powered, pre-registered experiments and remained robust to several methodological checks, including hypothesis guessing, game familiarity, demographic variables, between- and within-subjects designs, and variation in data exclusion criteria. These results support the role of culturally-elaborated beliefs about supernatural justice as a motivator of believer's adherence to prosocial norms. [ABSTRACT FROM AUTHOR]

The novel Coronavirus that spread around the world in early 2020 triggered a global pandemic and economic downturn that affected nearly everyone. Yet the crisis had a disproportionate impact on the poor and revealed how easily working-class individuals' financial security can be destabilised by factors beyond personal control. In a pre-registered longitudinal study of Americans (N = 233) spanning April 2019 to May 2020, we tested whether the pandemic altered beliefs about the extent to which poverty is caused by external forces and internal dispositions and support for economic inequality. Over this timespan, participants revealed a shift in their attributions for poverty, reporting that poverty is more strongly impacted by external-situational causes and less by internal-dispositional causes. However, we did not detect an overall mean-level change in opposition to inequality or support for government intervention. Instead, only for those who most strongly recognized the negative impact of COVID-19 did changes in poverty attributions translate to decreased support for inequality, and increased support for government intervention to help the poor. [ABSTRACT FROM AUTHOR]

Although much of human morality evolved in an environment of small group living, almost 6 billion people use the internet in the modern era. We argue that the technological transformation has created an entirely new ecosystem that is often mismatched with our evolved adaptations for social living. We discuss how evolved responses to moral transgressions, such as compassion for victims of transgressions and punishment of transgressors, are disrupted by two main features of the online context. First, the scale of the internet exposes us to an unnaturally large quantity of extreme moral content, causing compassion fatigue and increasing public shaming. Second, the physical and psychological distance between moral actors online can lead to ineffective collective action and virtue signaling. We discuss practical implications of these mismatches and suggest directions for future research on morality in the internet era., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Does believing that "effort doesn't pay" in society shape how people view dishonest-illegal transgressions? Across five studies, we show that when people view societal success as non-meritocratic-that is, more dependent on luck and circumstances than on hard work-they are more lenient in their moral judgements of dishonest-illegal transgressions. Perceiving society as non-meritocratic predicted greater justifiability of dishonest-illegal transgressions in the United States (Study 2), and across 42 countries (N = 49,574; Study 1). And inducing participants to view society as non-meritocratic increased justifiability of others' dishonest-illegal transgressions, via greater feelings of sympathy (Studies 3 and 4). Next, we investigated the contours of these effects. Perceiving societal success as non-meritocratic rather than based on hard work causes people to view dishonest-illegal transgressions as more justifiable if they are perpetrated by the poor, but not the rich (Study 4), and if the dishonest-illegal transgressions are related to economic striving, such as money laundering and dealing illegal drugs (Study 5). In sum, when people see a social system as unfair, they show greater tolerance for dishonest-illegal transgressions perpetrated to circumvent the system., (© 2024 The Authors. British Journal of Social Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.)

Moral psychology was shaped around three categories of agents and patients: humans, other animals, and supernatural beings. Rapid progress in artificial intelligence has introduced a fourth category for our moral psychology to deal with: intelligent machines. Machines can perform as moral agents, making decisions that affect the outcomes of human patients or solving moral dilemmas without human supervision. Machines can be perceived as moral patients, whose outcomes can be affected by human decisions, with important consequences for human-machine cooperation. Machines can be moral proxies that human agents and patients send as their delegates to moral interactions or use as a disguise in these interactions. Here we review the experimental literature on machines as moral agents, moral patients, and moral proxies, with a focus on recent findings and the open questions that they suggest.

Scientific evidence regularly guides policy decisions 1 , with behavioural science increasingly part of this process 2 . In April 2020, an influential paper 3 proposed 19 policy recommendations ('claims') detailing how evidence from behavioural science could contribute to efforts to reduce impacts and end the COVID-19 pandemic. Here we assess 747 pandemic-related research articles that empirically investigated those claims. We report the scale of evidence and whether evidence supports them to indicate applicability for policymaking. Two independent teams, involving 72 reviewers, found evidence for 18 of 19 claims, with both teams finding evidence supporting 16 (89%) of those 18 claims. The strongest evidence supported claims that anticipated culture, polarization and misinformation would be associated with policy effectiveness. Claims suggesting trusted leaders and positive social norms increased adherence to behavioural interventions also had strong empirical support, as did appealing to social consensus or bipartisan agreement. Targeted language in messaging yielded mixed effects and there were no effects for highlighting individual benefits or protecting others. No available evidence existed to assess any distinct differences in effects between using the terms 'physical distancing' and 'social distancing'. Analysis of 463 papers containing data showed generally large samples; 418 involved human participants with a mean of 16,848 (median of 1,699). That statistical power underscored improved suitability of behavioural science research for informing policy decisions. Furthermore, by implementing a standardized approach to evidence selection and synthesis, we amplify broader implications for advancing scientific evidence in policy formulation and prioritization., (© 2023. The Author(s).)

Over the last decade, robots continue to infiltrate the workforce, permeating occupations that once seemed immune to automation. This process seems to be inevitable because robots have ever-expanding capabilities. However, drawing from theories of cultural evolution and social learning, we propose that robots may have limited influence in domains that require high degrees of "credibility"; here we focus on the automation of religious preachers as one such domain. Using a natural experiment in a recently automated Buddhist temple (Study 1) and a fully randomized experiment in a Taoist temple (Study 2), we consistently show that religious adherents perceive robot preachers-and the institutions which employ them-as less credible than human preachers. This lack of credibility explains reductions in religious commitment after people listen to robot (vs. human) preachers deliver sermons. Study 3 conceptually replicates this finding in an online experiment and suggests that religious elites require perceived minds (agency and patiency) to be credible, which is partly why robot preachers inspire less credibility than humans. Our studies support cultural evolutionary theories of religion and suggest that escalating religious automation may induce religious decline. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Most humans believe in a god or gods, a belief that may promote prosociality toward coreligionists. A critical question is whether such enhanced prosociality is primarily parochial and confined to the religious ingroup or whether it extends to members of religious outgroups. To address this question, we conducted field and online experiments with Christian, Muslim, Hindu, and Jewish adults in the Middle East, Fiji, and the United States ( N = 4,753). Participants were given the opportunity to share money with anonymous strangers from different ethno-religious groups. We manipulated whether they were asked to think about their god before making their choice. Thinking about God increased giving by 11% (4.17% of the total stake), an increase that was extended equally to ingroup and outgroup members. This suggests that belief in a god or gods may facilitate intergroup cooperation, particularly in economic transactions, even in contexts with heightened intergroup tension.

Americans venerate rags-to-riches stories. Here we show that people view those who became rich more positively than those born rich and expect the Became Rich to be more sympathetic toward social welfare (Studies 1a and b). However, we also find that these intuitions are misguided. Surveys of wealthy individuals (Studies 2a and b) reveal that, compared with the Born Rich, the Became Rich perceive improving one's socioeconomic conditions as less difficult, which, in turn, predicts less empathy for the poor, less perceived sacrifices by the poor, more internal attributions for poverty, and less support for redistribution. Corroborating this, imagining having experienced upward mobility (vs. beginning and staying at the top) causes people to view such mobility as less difficult, reducing empathy and support for those failing to move up (Study 3). These findings suggest that becoming rich may shift views about the poor in ways that run counter to common intuitions and cultural assumptions., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

Objective. When medical resources are scarce, clinicians must make difficult triage decisions. When these decisions affect public trust and morale, as was the case during the COVID-19 pandemic, experts will benefit from knowing which triage metrics have citizen support. Design. We conducted an online survey in 20 countries, comparing support for 5 common metrics (prognosis, age, quality of life, past and future contribution as a health care worker) to a benchmark consisting of support for 2 no-triage mechanisms (first-come-first-served and random allocation). Results. We surveyed nationally representative samples of 1000 citizens in each of Brazil, France, Japan, and the United States and also self-selected samples from 20 countries (total N = 7599) obtained through a citizen science website (the Moral Machine). We computed the support for each metric by comparing its usability to the usability of the 2 no-triage mechanisms. We further analyzed the polarizing nature of each metric by considering its usability among participants who had a preference for no triage. In all countries, preferences were polarized, with the 2 largest groups preferring either no triage or extensive triage using all metrics. Prognosis was the least controversial metric. There was little support for giving priority to healthcare workers. Conclusions. It will be difficult to define triage guidelines that elicit public trust and approval. Given the importance of prognosis in triage protocols, it is reassuring that it is the least controversial metric. Experts will need to prepare strong arguments for other metrics if they wish to preserve public trust and morale during health crises., Highlights: We collected citizen preferences regarding triage decisions about scarce medical resources from 20 countries.We find that citizen preferences are universally polarized.Citizens either prefer no triage (random allocation or first-come-first served) or extensive triage using all common triage metrics, with "prognosis" being the least controversial.Experts will need to prepare strong arguments to preserve or elicit public trust in triage decisions., Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Jean-François Bonnefon acknowledges support from the grant ANR-17-EURE-0010 and the research foundation TSE-Partnership. The funding agreement ensured the authors’ independence in designing the study, interpreting the data, writing, and publishing the report., (© The Author(s) 2022.)

Although people report grave concern over their data privacy, they take little care to protect it. We suggest that this privacy paradox can be understood in part as the consequence of an evolutionary mismatch: Privacy intuitions evolved in an environment that was radically different from the one found online. This evolved privacy psychology leaves people disconnected from the consequence of online privacy threats., Competing Interests: Declaration of Conflicting Interests: The author(s) declared that there were no conflicts of interest with respect to the authorship or the publication of this article., (© The Author(s) 2021.)

The COVID-19 pandemic represents a massive global health crisis. Because the crisis requires large-scale behaviour change and places significant psychological burdens on individuals, insights from the social and behavioural sciences can be used to help align human behaviour with the recommendations of epidemiologists and public health experts. Here we discuss evidence from a selection of research topics relevant to pandemics, including work on navigating threats, social and cultural influences on behaviour, science communication, moral decision-making, leadership, and stress and coping. In each section, we note the nature and quality of prior research, including uncertainty and unsettled issues. We identify several insights for effective response to the COVID-19 pandemic and highlight important gaps researchers should move quickly to fill in the coming weeks and months.

Amidst rising economic inequality and mounting evidence of its pernicious social effects, what motivates opposition to inequality? Five studies (n = 34,442) show that attributing poverty to situational forces is associated with greater concern about inequality, preference for egalitarian policies and inequality-reducing behaviour. In Study 1, situational attributions for poverty were associated with reduced support for inequality across 34 countries. Study 2 replicated these findings with a nationally representative sample of Americans. Three experiments then tested whether situational attributions for poverty are malleable and motivate egalitarianism. Bolstering situational attributions for poverty through a writing exercise (Study 3) and a computer-based poverty simulation (Studies 4a and b) increased egalitarian action and reduced support for inequality immediately (Studies 3 and 4b), 1 d later and 155 d post-intervention (Study 4b). Causal attributions for poverty offer one accessible means of shaping inequality-reducing attitudes and actions. Situational attributions may be a potent psychological lever for lessening societal inequality.

When do people find it acceptable to sacrifice one life to save many? Cross-cultural studies suggested a complex pattern of universals and variations in the way people approach this question, but data were often based on small samples from a small number of countries outside of the Western world. Here we analyze responses to three sacrificial dilemmas by 70,000 participants in 10 languages and 42 countries. In every country, the three dilemmas displayed the same qualitative ordering of sacrifice acceptability, suggesting that this ordering is best explained by basic cognitive processes rather than cultural norms. The quantitative acceptability of each sacrifice, however, showed substantial country-level variations. We show that low relational mobility (where people are more cautious about not alienating their current social partners) is strongly associated with the rejection of sacrifices for the greater good (especially for Eastern countries), which may be explained by the signaling value of this rejection. We make our dataset fully available as a public resource for researchers studying universals and variations in human morality., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

Machines powered by artificial intelligence increasingly mediate our social, cultural, economic and political interactions. Understanding the behaviour of artificial intelligence systems is essential to our ability to control their actions, reap their benefits and minimize their harms. Here we argue that this necessitates a broad scientific research agenda to study machine behaviour that incorporates and expands upon the discipline of computer science and includes insights from across the sciences. We first outline a set of questions that are fundamental to this emerging field and then explore the technical, legal and institutional constraints on the study of machine behaviour.

With the rapid development of artificial intelligence have come concerns about how machines will make moral decisions, and the major challenge of quantifying societal expectations about the ethical principles that should guide machine behaviour. To address this challenge, we deployed the Moral Machine, an online experimental platform designed to explore the moral dilemmas faced by autonomous vehicles. This platform gathered 40 million decisions in ten languages from millions of people in 233 countries and territories. Here we describe the results of this experiment. First, we summarize global moral preferences. Second, we document individual variations in preferences, based on respondents' demographics. Third, we report cross-cultural ethical variation, and uncover three major clusters of countries. Fourth, we show that these differences correlate with modern institutions and deep cultural traits. We discuss how these preferences can contribute to developing global, socially acceptable principles for machine ethics. All data used in this article are publicly available.

Autonomous vehicles (AVs) should reduce traffic accidents, but they will sometimes have to choose between two evils, such as running over pedestrians or sacrificing themselves and their passenger to save the pedestrians. Defining the algorithms that will help AVs make these moral decisions is a formidable challenge. We found that participants in six Amazon Mechanical Turk studies approved of utilitarian AVs (that is, AVs that sacrifice their passengers for the greater good) and would like others to buy them, but they would themselves prefer to ride in AVs that protect their passengers at all costs. The study participants disapprove of enforcing utilitarian regulations for AVs and would be less willing to buy such an AV. Accordingly, regulating for utilitarian algorithms may paradoxically increase casualties by postponing the adoption of a safer technology., (Copyright © 2016, American Association for the Advancement of Science.)

American politicians often justify income inequality by referencing the opportunities people have to move between economic stations. Though past research has shown associations between income mobility and resistance to wealth redistribution policies, no experimental work has tested whether perceptions of mobility influence tolerance for inequality. In this article, we present a cross-national comparison showing that income mobility is associated with tolerance for inequality and experimental work demonstrating that perceptions of higher mobility directly affect attitudes toward inequality. We find support for both the prospect of upward mobility and the view that peoples' economic station is the product of their own efforts, as mediating mechanisms., (© The Author(s) 2016.)

Gomes and McCullough (2015) are to be commended on their high-powered attempt to replicate our earlier research (Shariff & Norenzayan, 2007). We suggest that notable differences between the two studies indicate that Gomes and McCullough were testing a different question. Here we place Gomes and McCullough's results in context with other studies and discuss how their findings may point to an interesting boundary condition of the original effect., ((c) 2015 APA, all rights reserved).)

If free-will beliefs support attributions of moral responsibility, then reducing these beliefs should make people less retributive in their attitudes about punishment. Four studies tested this prediction using both measured and manipulated free-will beliefs. Study 1 found that people with weaker free-will beliefs endorsed less retributive, but not consequentialist, attitudes regarding punishment of criminals. Subsequent studies showed that learning about the neural bases of human behavior, through either lab-based manipulations or attendance at an undergraduate neuroscience course, reduced people's support for retributive punishment (Studies 2-4). These results illustrate that exposure to debates about free will and to scientific research on the neural basis of behavior may have consequences for attributions of moral responsibility., (© The Author(s) 2014.)

The sanctioning of norm-transgressors is a necessary--though often costly--task for maintaining a well-functioning society. Prior to effective and reliable secular institutions for punishment, large-scale societies depended on individuals engaging in 'altruistic punishment'--bearing the costs of punishment individually, for the benefit of society. Evolutionary approaches to religion suggest that beliefs in powerful, moralizing Gods, who can distribute rewards and punishments, emerged as a way to augment earthly punishment in large societies that could not effectively monitor norm violations. In five studies, we investigate whether such beliefs in God can replace people's motivation to engage in altruistic punishment, and their support for state-sponsored punishment. Results show that, although religiosity generally predicts higher levels of punishment, the specific belief in powerful, intervening Gods reduces altruistic punishment and support for state-sponsored punishment. Moreover, these effects are specifically owing to differences in people's perceptions that humans are responsible for punishing wrongdoers.

We examine empirical evidence for religious prosociality, the hypothesis that religions facilitate costly behaviors that benefit other people. Although sociological surveys reveal an association between self-reports of religiosity and prosociality, experiments measuring religiosity and actual prosocial behavior suggest that this association emerges primarily in contexts where reputational concerns are heightened. Experimentally induced religious thoughts reduce rates of cheating and increase altruistic behavior among anonymous strangers. Experiments demonstrate an association between apparent profession of religious devotion and greater trust. Cross-cultural evidence suggests an association between the cultural presence of morally concerned deities and large group size in humans. We synthesize converging evidence from various fields for religious prosociality, address its specific boundary conditions, and point to unresolved questions and novel predictions.

We present two studies aimed at resolving experimentally whether religion increases prosocial behavior in the anonymous dictator game. Subjects allocated more money to anonymous strangers when God concepts were implicitly activated than when neutral or no concepts were activated. This effect was at least as large as that obtained when concepts associated with secular moral institutions were primed. A trait measure of self-reported religiosity did not seem to be associated with prosocial behavior. We discuss different possible mechanisms that may underlie this effect, focusing on the hypotheses that the religious prime had an ideomotor effect on generosity or that it activated a felt presence of supernatural watchers. We then discuss implications for theories positing religion as a facilitator of the emergence of early large-scale societies of cooperators.