Oxytocin enhances implicit social conformity to both in-group and out-group opinions

Dishonest collaboration in an intergroup context

Collaborations may sometimes increase the likelihood of engaging in dishonest behaviour. As yet, it remains unknown what factors contribute to this phenomenon. Here, we investigate whether it matters with whom people are collaborating for the extent to which they are dishonest. We aim to (I) replicate dishonest collaboration effects and (II) examine whether collaborating with an ingroup member (vs. outgroup member) amplifies dishonesty. In three pre-registered studies (N = 782), we used the sequential dyadic die-rolling paradigm in both student (Study 1: Lab context) and community samples (Studies 2-3: Field context). In this paradigm, two players form a dyad (either with an ingroup or an outgroup member) and earn winnings depending on both their own and the other's dice roll. Crucially, dice rolls are private, and players can inflate their winnings by misreporting their dice roll. Collectively, our studies replicate the dishonest collaboration effect, showing the robustness of collaborative dishonesty over samples and contexts. However, our studies suggest that dishonesty is similar when collaborating with an ingroup versus an outgroup member. Alternative processes are discussed that may play a role in collaborative dishonesty resulting in the absence of an intergroup effect.

Oxytocin Dynamics in the Body and Brain Regulated by the Receptor for Advanced Glycation End-Products, CD38, CD157, and Nicotinamide Riboside

Investigating the neurocircuit and synaptic sites of action of oxytocin (OT) in the brain is critical to the role of OT in social memory and behavior. To the same degree, it is important to understand how OT is transported to the brain from the peripheral circulation. To date, of these, many studies provide evidence that CD38, CD157, and receptor for advanced glycation end-products (RAGE) act as regulators of OT concentrations in the brain and blood. It has been shown that RAGE facilitates the uptake of OT in mother’s milk from the digestive tract to the cell surface of intestinal epithelial cells to the body fluid and subsequently into circulation in male mice. RAGE has been shown to recruit circulatory OT into the brain from blood at the endothelial cell surface of neurovascular units. Therefore, it can be said that extracellular OT concentrations in the brain (hypothalamus) could be determined by the transport of OT by RAGE from the circulation and release of OT from oxytocinergic neurons by CD38 and CD157 in mice. In addition, it has recently been found that gavage application of a precursor of nicotinamide adenine dinucleotide, nicotinamide riboside, for 12 days can increase brain OT in mice. Here, we review the evaluation of the new concept that RAGE is involved in the regulation of OT dynamics at the interface between the brain, blood, and intestine in the living body, mainly by summarizing our recent results due to the limited number of publications on related topics. And we also review other possible routes of OT recruitment to the brain.

Oxytocin and the Neurobiology of Prosocial Behavior

Humans are an unusually prosocial species, who engage in social behaviors that include altruism-whereby an individual engages in costly or risky acts to improve the welfare of another person-care, and cooperation. Current perspectives on the neurobiology of human prosociality suggest that it is deeply rooted in the neuroendocrine architecture of the social brain and emphasize the modulatory role of the neuropeptide hormone oxytocin. In this review, we provide a conceptual overview of the neurobiology of prosocial behavior with a focus on oxytocin's modulatory role in human prosociality. Specifically, we aim to encourage a better understanding of the peptide's susceptibility to diverse factors that produce heterogeneity in outcomes and the resulting methodological implications for measuring the behavioral effects of oxytocin in humans. After providing an overview of the state-of-the-art research on oxytocin's exogenous use, we elaborate on the peptide's modulatory role in the context of care-based altruism, cooperation, and conflict and discuss its potential for therapeutic interventions in psychiatric disorders characterized by social dysfunction.

Intranasal oxytocin in the treatment of autism spectrum disorders: A multilevel meta-analysis

Intranasal oxytocin has been shown to promote social functioning and has recently been applied as a treatment for autism spectrum disorders (ASD). The current meta-analysis aims to assess the crucial question of oxytocin's efficacy in the treatment of ASD. We performed a systematic literature search, including randomized, single- or double-blind/open-label and placebo-controlled clinical trials as well as single-arm, non-randomized and uncontrolled studies investigating exogenous oxytocin effect on ASD. A total of 28 studies (N = 726 ASD patients) met our predefined inclusion criteria. We used a multilevel meta-analytic model and found that oxytocin had beneficial effects on social functioning, but did not find strong evidence for symptoms improvement in the non-social domain. Our findings suggest that oxytocin administration can be regarded as an effective treatment for some core aspects of ASD, especially in the domain of social functioning, highlighting the promise of using oxytocin as a new-generation therapeutic to address core social impairments in ASD.

Oxytocin amplifies the influence of good intentions on social judgments

Studies have shown that the evolutionarily conserved neuropeptide oxytocin (OT) promotes various prosocial behaviors, yet there are few studies of the effect of OT on social judgments, especially on judgments when the actor's intention and the final outcome are incongruent. In a double-blind, placebo-controlled experiment, participants were asked to play the role of the recipient in a dictator game and to make social judgments about the dictator after intranasal OT administration. To isolate the outcome and the intention of the dictator's allocation, we developed a novel social judgment task in which recipients were told that 50% of the dictators' proposals would be reversed. The results showed that the effect of OT on social judgment was modulated by intention: OT increased goodness ratings only towards dictators with hyperfair intention. Our findings support the affiliative-motivation theory which states that OT enhances the affiliative motivation and recognition of positive-valence social stimuli.

Unraveling the role of oxytocin in the motivational structure of conflict

Current psychological perspectives emphasize “attack” and “defense” as the behavioral mechanisms underlying conflict. Here, we extend this view by highlighting the relevance of pathological altruism and the neuroendocrine pathways associated with hostile behaviors. Specifically, we elucidate the modulatory role of the neuropeptide hormone oxytocin in motivating extraordinary levels of in-group commitment that can promote extreme behaviors and endure conflict with out-groups.

Oxytocin Facilitates Social Learning by Promoting Conformity to Trusted Individuals

There is considerable interest in the role of the neuropeptide oxytocin in promoting social cohesion both in terms of promoting specific social bonds and also more generally for increasing our willingness to trust others and/or to conform to their opinions. These latter findings may also be important in the context of a modulatory role for oxytocin in improving the efficacy of behavioral therapy in psychiatric disorders. However, the original landmark studies claiming an important role for oxytocin in enhancing trust in others, primarily using economic game strategies, have been questioned by subsequent meta-analytic approaches or failure to reproduce findings in different contexts. On the other hand, a growing number of studies have consistently reported that oxytocin promotes conformity to the views of groups of in-group individuals. Most recently we have found that oxytocin can increase acceptance of social advice given by individual experts without influencing their perceived trustworthiness per se, but that increased conformity in this context is associated with how much an expert is initially trusted and liked. Oxytocin can also enhance the impact of information given by experts by facilitating expectancy and placebo effects. Here we therefore propose that a key role for oxytocin is not in facilitating social trust per se but in conforming to, and learning from, trusted individuals who are either in-group members and/or perceived experts. The implications of this for social learning and use of oxytocin as an adjunct to behavioral therapy in psychiatric disorders are discussed. Interpersonal trust within social groups is of key importance for social interactions, bonds, cooperation and learning and trust between different groups can also help ensure a stable and peaceful co-existence as well as mutually beneficial co-operation and trade. Trust is generally considered to be critical for co-operation and reciprocity in social and economic interactions but importantly trust also involves risk of potential injury if misplaced or broken and we have a natural aversion to taking such risks (Hardin, 2002; Ostrom and Walker, 2003). Indeed, an important factor influencing our trust behavior is that we are strongly motivated to avoid others betraying our trust (Bohnet and Zeckhauser, 2004; Bohnet et al., 2008). Trust can potentially be influenced by our assessment of the level of risk that trusting others might have and also by increased sensitivity to physical and/or other cues for detecting trustworthiness. It is therefore of great importance to identify both behavioral and physiological factors which can act to enhance trust, particularly in situations where individuals have impaired trust and therefore find it hard to interact socially with others and learn from them and/or to benefit optimally from cognitive and behavioral therapeutic strategies.

Socially Learned Attitude Change is not reduced in Medicated Patients with Schizophrenia

Schizophrenia is often associated with distinctive or odd social behaviours. Previous work suggests this could be due to a general reduction in conformity; however, this work only assessed the tendency to publicly agree with others, which may involve a number of different mechanisms. In this study, we specifically investigated whether patients display a reduced tendency to adopt other people’s opinions (socially learned attitude change). We administered a computerized conformity task, assumed to rely on reinforcement learning circuits, to 32 patients with schizophrenia or schizo-affective disorder and 39 matched controls. Each participant rated 153 faces for trustworthiness. After each rating, they were immediately shown the opinion of a group. After approximately 1 hour, participants were unexpectedly asked to rate all the faces again. We compared the degree of attitude change towards group opinion in patients and controls. Patients presented equal or more social influence on attitudes than controls. This effect may have been medication induced, as increased conformity was seen with higher antipsychotic dose. The results suggest that there is not a general decline in conformity in medicated patients with schizophrenia and that previous findings of reduced conformity are likely related to mechanisms other than reinforcement based social influence on attitudes.

The Role of Oxytocin in Antisocial Personality Disorders: A Systematic Review of the Literature

Background and aims: Antisocial personality disorder is an enduring mental disorder associated with significant disease burden and treatment difficulties. This is apparent within forensic populations. There is growing evidence to suggest that treatment with oxytocin could have some benefit in treating a range of psychiatric disorders. There are no reviews studying the use of oxytocin for patients with ASPD. We aim to present the first literature review on the use of oxytocin in patients with ASPD. Method: We searched relevant databases for original research on effect of oxytocin upon persons with a diagnosis of ASPD or healthy participants with symptoms seen in ASPD. Studies were included if they included healthy participants that evaluated the effect of oxytocin on symptoms relevant to ASPD, including empathy, inhibitory control, compliance, conformity, aggression, violence, and moral responsibility. Results: Thirty-six studies were included. There were a range of study designs, including randomized controlled trials, double blinded, single blinded, and unblinded controlled trials. The sample sizes in studies ranged from 20 to 259 participants. Studies looked at participants with a diagnosis of ASPD and participants with symptoms relevant to ASPD, including empathy, inhibitory control, compliance, conformity, aggression, violence, and moral responsibility. Oxytocin was found to demonstrate diversified effects, in most cases being associated with socially positive or non-criminogenic behaviors. However, some studies found opposite, and non-desirable, effects, e.g., an increase in violent inclinations to partners. The two studies looking at participants with ASPD had a number of limitations and had conflicting results on the impact that OT has on aggression in ASPD. Conclusions: This is the first systematic literature review exploring the potential use of oxytocin in managing ASPD and the symptoms of ASPD. It is apparent that there is a body of evidence addressing related symptoms in healthy individuals. There were diversified effects with oxytocin showing some benefits in promoting positive effects on symptoms of ASPD, but there were also studies showing non-desirable effects. It is difficult to draw any direct inferences from healthy control studies. Further high quality large sample studies are required to explore the effects of oxytocin in those with ASPD.

Endogenous Oxytocin Release Eliminates In-Group Bias in Monetary Transfers With Perspective-Taking

Oxytocin (OT) has been shown to facilitate trust, empathy and other prosocial behaviors. At the same time, there is evidence that exogenous OT infusion may not result in prosocial behaviors in all contexts, increasing in-group biases in a number of studies. The current investigation seeks to resolve this inconsistency by examining if endogenous OT release is associated with in-group bias. We studied a large group of participants (N = 399) in existing groups and randomly formed groups. Participants provided two blood samples to measure the change in OT after a group salience task and then made computer-mediated monetary transfer decisions to in-group and out-group members. Our results show that participants with an increase in endogenous OT showed no bias in monetary offers in the ultimatum game (UG) to out-group members compared to in-groups. There was also no bias in accepting UG offers, though in-group bias persisted for a unilateral monetary transfer. Our analysis shows that the strength of identification with one's group diminished the effects that an increase in OT had on reducing bias, but bias only recurred when group identification reached 87% of its maximum value. Our results indicate that the endogenous OT system appears to reduce in-group bias in some contexts, particularly those that require perspective-taking.

Oxytocin facilitation of acceptance of social advice is dependent upon the perceived trustworthiness of individual advisors

The neuropeptide oxytocin may increase social cohesion by making us more willing to trust others and/or to conform to their opinions. Here we investigated whether intranasal oxytocin can influence acceptance of advice given on solving everyday social problems by either individual expert (psychologist) or non-expert advisors with or without influencing their perceived likeability or trustworthiness. In a double-blind, between-subject, placebo-control design study in 160 male and female subjects, intranasal oxytocin (24IU) only significantly enhanced acceptance of advice given by female psychologists who were rated as the most trustworthy advisors. However, oxytocin itself did not alter either trustworthiness or likeability ratings. The oxytocin effect on acceptance of the female psychologist's advice was not maintained after a week, with subjects mainly reverting to their original solutions. These findings suggest that while oxytocin can transiently increase acceptance of advice from the most trustworthy individuals this is because it makes subjects more likely to conform to their opinions rather than enhancing their perceived trustworthiness or likeability. Thus in every day contexts oxytocin may primarily promote social cohesion by facilitating conformity towards the opinions of the most trusted individuals.

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.

Generous to whom? The influence of oxytocin on social discounting

Oxytocin is thought to play an essential role in pro-social behaviors, such as generosity and altruism, in humans. Yet, most research in humans that demonstrated the pro-social effect of oxytocin had participants interact with partners who were total strangers to them. In real life, however, people often interact with others varying in social relatedness with them (a concept known as social distance), ranging from their parents to total strangers. Here we employed the social-discounting framework to investigate whether the effect of oxytocin on prosociality depends on the social distance between the participants and their interaction partners. In a double-blind, placebo-controlled experiment (n=172 participants), we measured the amount of money participants were willing to forgo to another person as a function of social distance. We found that oxytocin administration selectively enhanced amount of money forgone toward total strangers, as opposed to someone closer to participants, suggesting that social distance constrained the pro-social effect of oxytocin.

The Neuropeptide Oxytocin Enhances Information Sharing and Group Decision Making Quality

Groups can make better decisions than individuals when members cooperatively exchange and integrate their uniquely held information and insights. However, under conformity pressures group members are biased towards exchanging commonly known information, and away from exchanging unique information, thus undermining group decision-making quality. At the neurobiological level, conformity associates with the neuropeptide oxytocin. A double-blind placebo controlled study found no evidence for oxytocin induced conformity. Compared to placebo groups, three-person groups whose members received intranasal oxytocin, focused more on unique information (i) and repeated this information more often (ii). These findings reveal oxytocin as a neurobiological driver of group decision-making processes.

Fear or greed? Oxytocin regulates inter-individual conflict by enhancing fear in men

People may choose non-cooperation in social dilemmas either out of fear (if others choose to defect) or out of greed (when others choose to cooperate). Previous studies have shown that exogenous oxytocin motivates a "tend and defend" pattern in inter-group conflict in which oxytocin stimulates in-group cooperation and out-group defense. Using a double-blind placebo-controlled design combined with a modified Prisoner's dilemma game (PDG), we examined the effect of oxytocin on social motivations in inter-individual conflict in men. Results showed that compared with the placebo group, oxytocin-exposed participants were less cooperative in general. Specifically, oxytocin amplified the effect of fear on defection but did not influence the effect of greed. Another non-social control study confirmed participants' decisions were sensitive to social factors. Our findings suggest that even when social group conflict is removed, oxytocin promotes distrust of strangers in "me and you" inter-individual conflict by elevating social fear in men.

Oxytocin Effect on Collective Decision Making: A Randomized Placebo Controlled Study

Collective decision making often benefits both the individuals and the group in a variety of contexts. However, for the group to be successful, individuals should be able to strike a balance between their level of competence and their influence on the collective decisions. The hormone oxytocin has been shown to promote trust, conformism and attention to social cues. We wondered if this hormone may increase participants’ (unwarranted) reliance on their partners’ opinion, resulting in a reduction in collective benefit by disturbing the balance between influence and competence. To test this hypothesis we employed a randomized double-blind placebo-controlled design in which male dyads self-administered intranasal oxytocin or placebo and then performed a visual search task together. Compared to placebo, collective benefit did not decrease under oxytocin. Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin. Moreover, trial-by-trial analysis showed that under oxytocin the more competent member of each dyad was less likely to change his mind during disagreements, while the less competent member showed a greater willingness to change his mind and conform to the opinion of his more reliable partner. This role-dependent effect may be mediated by enhanced monitoring of own and other’s performance level under oxytocin. Such enhanced social learning could improve the balance between influence and competence and lead to efficient and beneficial collaboration.