Oxytocin and Intergroup Conflict: Human society is organized into groups, such as those based on nationality or religion, which can lead to intergroup conflicts, with sometimes devastating consequences. Intergroup conflict engages a human behavior termed parochial altruism: For example, a soldier who fights against the enemy at risk to themselves to protect their country is a parochial altruist. De Dreu et al. (p. 1408 ; see the cover; see the News story by Miller ) have discovered a role for oxytocin, a neuropeptide produced in the hypothalamus, in regulating parochial altruism during human intergroup competition and conflict. Oxytocin is already known to play a role in trusting behavior, and naturally occurring genetic variants of the oxytocin receptor exist within the human population. Administration of oxytocin modulated defense-related aggression toward competing groups, but did not affect unprovoked, hateful behavior. Thus, there may be a neurobiological basis for intergroup conflict in humans.

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.

Unethical behavior by “ordinary” people poses significant societal and personal challenges. We present a novel framework centered on the role of self-serving justification to build upon and advance the rapidly expanding research on intentional unethical behavior of people who value their morality highly. We propose that self-serving justifications emerging before and after people engage in intentional ethical violations mitigate the threat to the moral self, enabling them to do wrong while feeling moral. Pre-violation justifications lessen the anticipated threat to the moral self by redefining questionable behaviors as excusable. Post-violation justifications alleviate the experienced threat to the moral self through compensations that balance or lessen violations. We highlight the psychological mechanisms that prompt people to do wrong and feel moral, and suggest future research directions regarding the temporal dimension of self-serving justifications of ethical misconduct.

Significance: Recent financial scandals highlight the devastating consequences of corruption. While much is known about individual immoral behavior, little is known about the collaborative roots of curruption. In a novel experimental paradigm, people could adhere to one of two competing moral norms: collaborate vs. be honest. Whereas collaborative settings may boost honesty due to increased observability, accountability, and reluctance to force others to become accomplices, we show that collaboration, particularly on equal terms, is inductive to the emergence of corruption. When partners' profits are not aligned, or when individuals complete a comparable task alone, corruption levels drop. These findings reveal a dark side of collaboration, suggesting that human cooperative tendencies, and not merely greed, take part in shaping corruption.