Oxytocin-enforced norm compliance reduces xenophobic outgroup rejection.

Never before have individuals had to adapt to social environments defined by such magnitudes of ethnic diversity and cultural differentiation. However, neurobiological evidence informing about strategies to reduce xenophobic sentiment and foster altruistic cooperation with outsiders is scarce. In a series of experiments settled in the context of the current refugee crisis, we tested the propensity of 183 Caucasian participants to make donations to people in need, half of whom were refugees (outgroup) and half of whom were natives (ingroup). Participants scoring low on xenophobic attitudes exhibited an altruistic preference for the outgroup, which further increased after nasal delivery of the neuropeptide oxytocin. In contrast, participants with higher levels of xenophobia generally failed to exhibit enhanced altruism toward the outgroup. This tendency was only countered by pairing oxytocin with peer-derived altruistic norms, resulting in a 74% increase in refugee-directed donations. Collectively, these findings reveal the underlying sociobiological conditions associated with outgroup-directed altruism by showing that charitable social cues co-occurring with enhanced activity of the oxytocin system reduce the effects of xenophobia by facilitating prosocial behavior toward refugees.

Impact of nutrition on social decision making.

Food intake is essential for maintaining homeostasis, which is necessary for survival in all species. However, food intake also impacts multiple biochemical processes that influence our behavior. Here, we investigate the causal relationship between macronutrient composition, its bodily biochemical impact, and a modulation of human social decision making. Across two studies, we show that breakfasts with different macronutrient compositions modulated human social behavior. Breakfasts with a high-carbohydrate/protein ratio increased social punishment behavior in response to norm violations compared with that in response to a low carbohydrate/protein meal. We show that these macronutrient-induced behavioral changes in social decision making are causally related to a lowering of plasma tyrosine levels. The findings indicate that, in a limited sense, "we are what we eat" and provide a perspective on a nutrition-driven modulation of cognition. The findings have implications for education, economics, and public policy, and emphasize that the importance of a balanced diet may extend beyond the mere physical benefits of adequate nutrition.

The Neuropeptide Oxytocin Induces a Social Altruism Bias.

Current psychological concepts of social and ecological responsibility emphasize the relevance of altruism, suggesting that more altruistic individuals are more likely to engage in sustainable behaviors. Emerging evidence indicates a central role of the neuropeptide oxytocin in promoting altruism. Whether this influence extends to ecological responsibility or is limited to the social domain remains unknown. In two independent experiments involving 172 human participants, we addressed this question by exposing subjects to a sustainability-related monetary donation task, with the option to support either socially or ecologically framed charities. We found that oxytocin induced a context-dependent change in altruistic behavior away from pro-environmental toward pro-social donations, while keeping constant the overall proportion of donated money. This pro-social bias transcended to the domain of sustainable consumption. Collectively, our findings demonstrate that altruistic priorities vary as a function of oxytocin system activity, which has implications for the promotion of pro-environmental attitudes and eco-friendly behaviors. SIGNIFICANCE STATEMENT: Individual responses to ecological and social sustainability require a shift in personal priorities away from selfish to more altruistic behaviors. Emerging evidence indicates a central role of the hypothalamic peptide oxytocin in promoting altruism, but whether the influence of oxytocin benefits altruistic decision-making in the context of ecological and social sustainability is unclear. In two independent behavioral experiments involving 172 human subjects, we show that heightened oxytocin system activity induces a social altruism bias at the cost of ecological responsibility. Our results have fundamental implications for policy interventions and business strategies designed to sustain ecological resources by suggesting that a social framing may attract more individuals to engage in pro-environmental and eco-friendly behaviors.

Enhancement in dopamine reduces generous behaviour in women.

Generosity is a human behavior common in social contexts. However, humans are not equally generous to everyone alike. Instead, generosity decreases as a function of social distance, an effect called social discounting. Studies show that such social discounting effect depends on diverse factors including personality traits, cultures, stress or hormonal levels. Recently, the importance of the neurotransmitter dopamine in regulating social interactions has been highlighted. However, it remains unclear how exactly dopamine agonist administration modulates generous behavior as a function of social discounting. Here, we investigate the causal effect of dopamine agonist administration on social discounting in a pharmacological intervention study. We employ a randomized, double-blind, within-subject design to investigate the impact of the D2/D3 receptor agonist pramipexole on social discounting by keeping gender constant. We apply hyperbolic social discount model to the data and provide evidence that women under pramipexole become less generous in general, especially towards close others. Our results highlight the crucial role of dopamine in social decision making.

Human Cooperation and Its Underlying Mechanisms.

Cooperation is a uniquely human behavior and can be observed across cultures. In order to maintain cooperative behavior in society, people are willing to punish deviant behavior on their own expenses and even without any personal benefits. Cooperation has been object of research in several disciplines. Psychologists, economists, sociologists, biologists, and anthropologists have suggested several motives possibly underlying cooperative behavior. In recent years, there has been substantial progress in understanding neural mechanisms enforcing cooperation. Psychological as well as economic theories were tested for their plausibility using neuroscientific methods. For example, paradigms from behavioral economics were adapted to be tested in the magnetic resonance imaging (MRI) scanner. Also, related brain functions were modulated by using transmagnetic brain stimulation (TMS). While cooperative behavior has often been associated with positive emotions, noncooperative behavior was found to be linked to negative emotions. On a neural level, the temporoparietal junction (TPJ), the striatum, and other reward-related brain areas have been shown to be activated by cooperation, whereas noncooperation has mainly been associated with activity in the insula.

A neural link between generosity and happiness.

Generous behaviour is known to increase happiness, which could thereby motivate generosity. In this study, we use functional magnetic resonance imaging and a public pledge for future generosity to investigate the brain mechanisms that link generous behaviour with increases in happiness. Participants promised to spend money over the next 4 weeks either on others (experimental group) or on themselves (control group). Here, we report that, compared to controls, participants in the experimental group make more generous choices in an independent decision-making task and show stronger increases in self-reported happiness. Generous decisions engage the temporo-parietal junction (TPJ) in the experimental more than in the control group and differentially modulate the connectivity between TPJ and ventral striatum. Importantly, striatal activity during generous decisions is directly related to changes in happiness. These results demonstrate that top-down control of striatal activity plays a fundamental role in linking commitment-induced generosity with happiness.

A matter of distance-The effect of oxytocin on social discounting is empathy-dependent.

Generosity is an important behavior enriching human society and can be observed across cultures. However, generosity has been shown to be modulated as a function of social distance, also referred to as social discounting. Oxytocin and empathy are other factors that have been shown to play an important role in generous behavior. However, how exactly oxytocin and empathy impact social discounting is yet unknown. Here, we administered oxytocin or placebo in a double-blind design, and measured social discounting behavior. Additionally, individual differences in empathy were assessed. Our results show that the effect of oxytocin on generous behavior is modulated by trait empathy; only for those subjects who received oxytocin there was a positive correlation between individual trait empathy and their generous behavior towards close others.

Generalized Negative Reciprocity in the Dictator Game--How to Interrupt the Chain of Unfairness.

Humans are tremendously sensitive to unfairness. Unfairness provokes strong negative emotional reactions and influences our subsequent decision making. These decisions might not only have consequences for ourselves and the person who treated us unfairly but can even transmit to innocent third persons--a phenomenon that has been referred to as generalized negative reciprocity. In this study we aimed to investigate whether regulation of emotions can interrupt this chain of unfairness. Real allocations in a dictator game were used to create unfair situations. Three different regulation strategies, namely writing a message to the dictator who made an unfair offer, either forwarded or not forwarded, describing a neutral picture and a control condition in which subjects just had to wait for three minutes, were then tested on their ability to influence the elicited emotions. Subsequently participants were asked to allocate money between themselves and a third person. We show that writing a message which is forwarded to the unfair actor is an effective emotion regulation strategy and that those participants who regulated their emotions successfully by writing a message made higher allocations to a third person. Thus, using message writing as an emotion regulation strategy can interrupt the chain of unfairness.

Helping or punishing strangers: neural correlates of altruistic decisions as third-party and of its relation to empathic concern.

Social norms are a cornerstone of human society. When social norms are violated (e.g., fairness) people can either help the victim or punish the violator in order to restore justice. Recent research has shown that empathic concern influences this decision to help or punish. Using functional magnetic resonance imaging (fMRI) we investigated the neural underpinnings of third-party help and punishment and the involvement of empathic concern. Participants saw a person violating a social norm, i.e., proposing unfair offers in a dictator game, at the expense of another person. The participants could then decide to either punish the violator or help the victim. Our results revealed that both third-party helping as well as third-party punishing activated the bilateral striatum, a region strongly related with reward processing, indicating that both altruistic decisions share a common neuronal basis. In addition, also different networks were involved in the two processes compared with control conditions; bilateral striatum and the right lateral prefrontal cortex (lPFC) during helping and bilateral striatum as well as left lPFC and ventral medial prefrontal cortex (vmPFC) during punishment. Further we found that individual differences in empathic concern influenced whether people prefer to help or to punish. People with high empathic concern helped more frequently, were faster in their decision and showed higher activation in frontoparietal regions during helping compared with punishing. Our findings provide insights into the neuronal basis of human altruistic behavior and social norm enforcement mechanism.

Be nice if you have to--the neurobiological roots of strategic fairness.

Social norms, such as treating others fairly regardless of kin relations, are essential for the functioning of human societies. Their existence may explain why humans, among all species, show unique patterns of prosocial behaviour. The maintenance of social norms often depends on external enforcement, as in the absence of credible sanctioning mechanisms prosocial behaviour deteriorates quickly. This sanction-dependent prosocial behaviour suggests that humans strategically adapt their behaviour and act selfishly if possible but control selfish impulses if necessary. Recent studies point at the role of the dorsolateral prefrontal cortex (DLPFC) in controlling selfish impulses. We test whether the DLPFC is indeed involved in the control of selfish impulses as well as the strategic acquisition of this control mechanism. Using repetitive transcranial magnetic stimulation, we provide evidence for the causal role of the right DLPFC in strategic fairness. Because the DLPFC is phylogenetically one of the latest developed neocortical regions, this could explain why complex norm systems exist in humans but not in other social animals.

Neural correlates of receiving an apology and active forgiveness: an FMRI study.

Interpersonal conflicts are a common element of many social relationships. One possible process in rebuilding social relationships is the act of apologizing. Behavioral studies have shown that apologies promote forgiveness. However, the neural bases of receiving an apology and forgiveness are still unknown. Hence, the aim of the present fMRI study was to investigate brain processes involved in receiving an apology and active forgiveness of an ambiguous offense. We asked one group of participants (player A) to make decisions, which were either positive or negative for another group of participants (player B). The intention of player A was ambiguous to player B. In case of a negative impact, participants in the role of player A could send an apology message to participants in the role of player B. Subsequently players B were asked whether they wanted to forgive player A for making a decision with negative consequences. We found that receiving an apology yielded activation in the left inferior frontal gyrus, the left middle temporal gyrus, and left angular gyrus. In line with previous research we found that forgiving judgments activated the right angular gyrus.