Michel J. J. Handgraaf

The Neuropeptide Oxytocin Regulates Parochial Altruism in Intergroup Conflict Among Humans

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. A hypothalamic hormone modulates bonding within a group and defense-related aggression between competing groups. 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.

Oxytocin promotes human ethnocentrism

Human ethnocentrism—the tendency to view ones 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.

Less power or powerless? Egocentric empathy gaps and the irony of having little versus no power in social decision making

The authors investigate the effect of power differences and associated expectations in social decision making. Using a modified ultimatum game, the authors show that allocators lower their offers to recipients when the power difference shifts in favor of the allocator. Remarkably, however, when recipients are completely powerless, offers increase. This effect is mediated by a change in framing of the situation: When the opponent is without power, feelings of social responsibility are evoked. On the recipient side, the authors show that recipients do not anticipate these higher outcomes resulting from powerlessness. They prefer more power over less, expecting higher outcomes when they are more powerful, especially when less power entails powerlessness. Results are discussed in relation to empathy gaps and social responsibility.

Social Utility in Ultimatum Bargaining

In this article we will provide an overview of factors that influence the weight that self-interest and equity related motives receive in ultimatum bargaining. These factors are grouped into three main categories: factors relating to the context of the game, factors relating to the parties involved, and factors related to characteristics of the game. Results of the studies are discussed in relation to the concept of social utility. The authors point out possible omissions in the literature—especially the lack of interest for the behavior of recipients—and recommend directions for future research.

Ethical manoeuvring: why people avoid both major and minor lies.

This research examines whether and why people manoeuvre their unethical behaviour so as to maximize material gains at a minimal psychological cost. Employing an anonymous die-under-cup paradigm, we asked people to report the outcome of a private die roll and gain money as a function of their reports. Supporting self-concept maintenance theory, results showed that people avoid both major lies (i.e. over-reporting the highest possible outcome) and minor lies (yielding little material gain), but did over-report intermediate outcomes when this implied a substantial increase compared to a walk-away value. Results suggest that lying is psychologically costly. We propose that organizations allowing freedom of choice while narrowing the available ways to unethically boost personal profit should see a decrease in unethical behaviour among their employees.

Oxytocin Motivates Non-Cooperation in Intergroup Conflict to Protect Vulnerable In-Group Members

Intergroup conflict is often driven by an individuals motivation to protect oneself and fellow group members against the threat of out-group aggression, including the tendency to pre-empt out-group threat through a competitive approach. Here we link such defense-motivated competition to oxytocin, a hypothalamic neuropeptide involved in reproduction and social bonding. An intergroup conflict game was developed to disentangle whether oxytocin motivates competitive approach to protect (i) immediate self-interest, (ii) vulnerable in-group members, or (iii) both. Males self-administered oxytocin or placebo (double-blind placebo-controlled) and made decisions with financial consequences to themselves, their fellow in-group members, and a competing out-group. Game payoffs were manipulated between-subjects so that non-cooperation by the out-group had high vs. low impact on personal payoff (personal vulnerability), and high vs. low impact on payoff to fellow in-group members (in-group vulnerability). When personal vulnerability was high, non-cooperation was unaffected by treatment and in-group vulnerability. When personal vulnerability was low, however, in-group vulnerability motivated non-cooperation but only when males received oxytocin. Oxytocin fuels a defense-motivated competitive approach to protect vulnerable group members, even when personal fate is not at stake.

Oxytocin modulates selection of allies in intergroup conflict

In intergroup competition and conflict, humans benefit from coalitions with strong partners who help them to protect their in-group and prevail over competing out-groups. Here, we link oxytocin, a neuropeptide produced in the hypothalamus, to ally selection in intergroup competition. In a double-blind placebo-controlled experiment, males self-administered oxytocin or placebo, and made selection decisions about six high-threat and six low-threat targets as potential allies in intergroup competition. Males given oxytocin rather than placebo viewed high-threat targets as more useful allies and more frequently selected them into their team than low-threat targets.

The salience of a recipient’s alternatives: Inter- and intrapersonal comparison in ultimatum games

The social utility model suggests that in social decision-making, both inter- and intrapersonal comparisons are important in assessing the utility of a decision outcome. In the ultimatum game both these comparisons play a role. This is especially true for recipients reacting to an unfair offer. We propose that the relative weights inter- and intrapersonal comparisons receive in ultimatum games depend on the way the decision is structured. In three studies we show that presenting recipients with a straightforward choice instead of the usual accept/reject question makes recipients more inclined to accept unfair offers. Moreover, the existence of an alternative outcome, i.e., the fact that refusal of the offer also leads to a substantial outcome, similarly raises the level of acceptances in a standard ultimatum game. Results are discussed in relation to the joint/separate evaluation disparity and the distinction between occurrences and non-occurrences.

Write when hot - Submit when not: seasonal bias in peer review or acceptance?

At a top psychology journal, Psychological Science (PS), submissions peak during the summer months. We tested whether this seasonal submission bias decreases the likelihood of a paper being accepted in that period. Month of submission data was obtained for all 575 publications in PS for the period 2003–2006. Whereas submissions to PS were higher in the summer, there was no evidence that most accepted publications were originally submitted in the summer. Thus, contributors submit to PS when the likelihood of acceptance is the lowest – creating their own entrance barrier. A similar seasonal pattern was not identified for Personality and Social Psychology Bulletin, another top psychology journal. Using the Web of Knowledge database, we further assessed whether overcoming the seasonal entrance barrier influences the number of citations a paper receives in subsequent years. We discuss the possibility that the different rejections policies in the two journals, employing desk rejections or not, may explain this discrepancy, and explore a range of alternative hypotheses.

Reply to Chen et al.: Perhaps goodwill is unlimited but oxytocin-induced goodwill is not

Chen et al. (1) raise several issues with the data and interpretations published in De Dreu et al. (2). We appreciate their constructive remarks. Here, we address their concerns and explain why our data do, in fact, show that oxytocin promotes human ethnocentrism.