Humans regulate intergroup conflict through parochial altruism; they self-sacrifice to contribute to in-group welfare and to aggress against competing out-groups. Parochial altruism has distinct survival functions, and the brain may have evolved to sustain and promote in-group cohesion and effectiveness and to ward off threatening out-groups. Here, we have linked oxytocin, a neuropeptide produced in the hypothalamus, to the regulation of intergroup conflict. In three experiments using double-blind placebo-controlled designs, male participants self-administered oxytocin or placebo and made decisions with financial consequences to themselves, their in-group, and a competing out-group. Results showed that oxytocin drives a "tend and defend" response in that it promoted in-group trust and cooperation, and defensive, but not offensive, aggression toward competing out-groups.

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Human ethnocentrism—the tendency to view one's group as centrally important and superior to other groups—creates intergroup bias that fuels prejudice, xenophobia, and intergroup violence. Grounded in the idea that ethnocentrism also facilitates within-group trust, cooperation, and coordination, we conjecture that ethnocentrism may be modulated by brain oxytocin, a peptide shown to promote cooperation among in-group members. In double-blind, placebo-controlled designs, males self-administered oxytocin or placebo and privately performed computer-guided tasks to gauge different manifestations of ethnocentric in-group favoritism as well as out-group derogation. Experiments 1 and 2 used the Implicit Association Test to assess in-group favoritism and out-group derogation. Experiment 3 used the infrahumanization task to assess the extent to which humans ascribe secondary, uniquely human emotions to their in-group and to an out-group. Experiments 4 and 5 confronted participants with the option to save the life of a larger collective by sacrificing one individual, nominated as in-group or as out-group. Results show that oxytocin creates intergroup bias because oxytocin motivates in-group favoritism and, to a lesser extent, out-group derogation. These findings call into question the view of oxytocin as an indiscriminate “love drug” or “cuddle chemical” and suggest that oxytocin has a role in the emergence of intergroup conflict and violence.

Recent research suggests that refraining from cheating in tempting situations requires self-control, which indicates that serving self-interest is an automatic tendency. However, evidence also suggests that people cheat to the extent that they can justify their unethical behavior to themselves. To merge these different lines of research, we adopted a dual-system approach that distinguished between the intuitive and deliberative cognitive systems. We suggest that for people to restrict their dishonest behavior, they need to have enough time and no justifications for self-serving unethical behavior. We employed an anonymous die-under-cup task in which participants privately rolled a die and reported the outcome to determine their pay. We manipulated the time available for participants to report their outcome (short vs. ample). The results of two experiments support our prediction, revealing that the dark side of people’s automatic self-serving tendency may be overcome when time to decide is ample and private justifications for dishonesty are not available.

Cooperation is essential for completing tasks that individuals cannot accomplish alone. Whereas the benefits of cooperation are clear, little is known about its possible negative aspects. Introducing a novel sequential dyadic die-rolling paradigm, we show that collaborative settings provide fertile ground for the emergence of corruption. In the main experimental treatment the outcomes of the two players are perfectly aligned. Player A privately rolls a die, reports the result to player B, who then privately rolls and reports the result as well. Both players are paid the value of the reports if, and only if, they are identical (e.g., if both report 6, each earns €6). Because rolls are truly private, players can inflate their profit by misreporting the actual outcomes. Indeed, the proportion of reported doubles was 489% higher than the expected proportion assuming honesty, 48% higher than when individuals rolled and reported alone, and 96% higher than when lies only benefited the other player. Breaking the alignment in payoffs between player A and player B reduced the extent of brazen lying. Despite player B's central role in determining whether a double was reported, modifying the incentive structure of either player A or player B had nearly identical effects on the frequency of reported doubles. Our results highlight the role of collaboration-particularly on equal terms-in shaping corruption. These findings fit a functional perspective on morality. When facing opposing moral sentiments-to be honest vs. to join forces in collaboration-people often opt for engaging in corrupt collaboration.cooperation | corruption | decision making | behavioral ethics |

We test the theory that shame evolved as a defense against being devalued by others. By hypothesis, shame is a neurocomputational program tailored by selection to orchestrate cognition, motivation, physiology, and behavior in the service of: (i) deterring the individual from making choices where the prospective costs of devaluation exceed the benefits, (ii) preventing negative information about the self from reaching others, and (iii) minimizing the adverse effects of devaluation when it occurs. Because the unnecessary activation of a defense is costly, the shame system should estimate the magnitude of the devaluative threat and use those estimates to cost-effectively calibrate its activation: Traits or actions that elicit more negative evaluations from others should elicit more shame. As predicted, shame closely tracks the threat of devaluation in the United States (r = .69), India (r = .79), and Israel (r = .67). Moreover, shame in each country strongly tracks devaluation in the others, suggesting that shame and devaluation are informed by a common species-wide logic of social valuation. The shame-devaluation link is also specific: Sadness and anxietyemotions that coactivate with shame-fail to track devaluation. To our knowledge, this constitutes the first empirical demonstration of a close, specific match between shame and devaluation within and across cultures.shame | emotion | valuation | culture | evolutionary psychology I n all known foraging societies past and present, humans have lived embedded in dense networks of cooperative and competitive interactions, a condition that is believed to have prevailed during the evolution of our species (1-3). Individuals in such social ecologies suffered or prospered depending on the summed effects of the choices of others-such as when and how often to share food, to provide care for another's child, to defer in conflicts, and so on. Ancestrally, the difference between an individual reproducing successfully, struggling, or dying early would have depended (in part) on the degree to which others traded off their own welfare for the welfare of that individual.Over the last fifty years, evolutionary researchers have identified a number of selection pressures that favored the evolution of decision systems that regulate welfare trade-offs between individuals, including kin selection (4), reciprocity/exchange (5, 6), risk-pooling (2), parenting (7), mating (8), externality management (9), and the asymmetric war of attrition (10). These theories, in turn, led to the empirical discovery of various choice architectures that evolved to produce best-bet welfare trade-off decisions given the information available to the actor about a potential recipient [e.g., how to respond to cues of genetic relatedness; how to respond to cues predicting the recipient's ability to effectively assert and defend her or his interests; how to respond to cues indicating a potential partner tends to cheat or free-ride (11-16)].In short, favorable valuation by others was a critical resource for our anc...

Is self-serving lying intuitive? Or does honesty come naturally? Many experiments have manipulated reliance on intuition in behavioral-dishonesty tasks, with mixed results. We present two meta-analyses (with evidential value) testing whether an intuitive mind-set affects the proportion of liars ( k = 73; n = 12,711) and the magnitude of lying ( k = 50; n = 6,473). The results indicate that when dishonesty harms abstract others, promoting intuition causes more people to lie, log odds ratio = 0.38, p = .0004, and people to lie more, Hedges’s g = 0.26, p < .0001. However, when dishonesty inflicts harm on concrete others, promoting intuition has no significant effect on dishonesty ( p > .63). We propose one potential explanation: The intuitive appeal of prosociality may cancel out the intuitive selfish appeal of dishonesty, suggesting that the social consequences of lying could be a promising key to the riddle of intuition’s role in honesty. We discuss limitations such as the relatively unbalanced distribution of studies using concrete versus abstract victims and the overall large interstudy heterogeneity.

Does everybody lie? A dominant view is that lying is part of everyday social interaction.Recent research, however, has claimed, that robust individual differences exist, with most people reporting that they do not lie, and only a small minority reporting very frequent lying. In this study, we found most people to subjectively report little or no lying. Importantly, we found self-reports of frequent lying to positively correlate with real-life cheating and psychopathic tendencies. Our findings question whether lying is normative and common among most people, and instead suggest that most people are honest most of the time and that a small minority lies frequently.