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Although oxytocin has been shown to enhance trust behavior, to date no study has directly established whether oxytocin can modulate the effect of repair strategies on restoring damaged trust. In the current double-blind, between-subjects, placebo-controlled design study, two repair strategies were used to examine the effect of intranasal oxytocin administration on modulating trust restoration in a revised trust game. The results showed that although oxytocin had no overall effect on modulating trust restoration, it did have a significant gender specific effect. Female subjects showed less evidence for trust repair in the oxytocin compared with the placebo treatment group. This suggests that oxytocin may make female subjects exhibit more punitive behavior towards partners who violate their trust and less sensitive to repair strategies provided by them. Interestingly, this gender specific effect was more evident in the context of attempted trust repair using financial compensation. However, it also extended to both apology alone and no compensation conditions, but not to the fair one, in females exhibiting high trait forgiveness. Thus females with a more forgiving attitude towards betrayal may actually be more likely to punish betrayal following oxytocin treatment.
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... One study that investigated OT effects regarding trust repair included both women and men, but the focus of the study was on trust betrayal and participants therefore received intranasal OT only after experiencing trust betrayal in the game (Yao et al., 2014). They found that OT led to significantly reduced trust repair after trust betrayal in females, while there was no significant difference for male participants. ...
... This study aims to answer several open research questions by investigating the effects of intranasal oxytocin in both men and women in their luteal phase using the same incentivized trust paradigm with facially manipulated opposite-sex interaction partners. First, we investigate whether OT's trust enhancing effects in men, as shown in the seminal study by Kosfeld et al. (2005), expands to women, given that this research question surprisingly has not been thoroughly addressed to date (but see Yao et al., 2014). To do this, we included women who did not take any hormonal contraceptives, and who therefore could be tested during a standardized phase of their menstrual cycle, namely the luteal phase. ...
... First, high plasma OT levels in women seem to be related to poor quality and reduced contact with friends, family and the romantic partner (Taylor, 2006). Second, women who received intranasal OT showed less evidence for trust repair after trust betrayal in the trust game than women who received placebo (Yao et al., 2014). In contrast, OT administered to single males increased the tolerance of being disliked by females . ...
Thesis
By modulating social approach behavior, oxytocin critically affects the formation and maintenance of monogamous relationships. A seminal study showed that in men, oxytocin increases trust and hence approach behavior towards unfamiliar others. In women, however, oxytocin’s effects on trust are still unknown. Furthermore, the decision whether to trust a potential romantic partner or not is strongly influenced by facial features such as attractiveness and threat. The former acts as a signal of good reproductive fitness, the latter as a signal of potential trust abuse, both being highly relevant in a mating context. This dissertation thus studies largely unknown gender differences in the relevance of attractiveness and threat by using a refined trust game with interaction partners that vary in these facial features. It furthermore addresses the research gap of gender differences in oxytocin’s effects on trust by systematically comparing single men and women in the luteal phase. In Chapter 1, literature is reviewed on the psychobiological factors and gender differences in social approach behavior and trust, and on possible ways to measure trust. Chapter 2 presents a refined, incentivized trust game, which includes photos of interaction partners that vary in facial attractiveness and threat. Results from 93 participants (all singles; 46 women during their luteal phase) with romantic interest in the opposite sex show that both women and men trusted attractive and unthreatening interaction partners more often. Moreover, women’s trust behavior was more strongly affected by threat than by attractiveness, whereas men’s trust behavior was equally affected by both features. From an evolutionary perspective, it might be advantageous for women to be more vigilant towards threat cues due to a higher parental investment. For men, on the other hand, it might be more beneficial to approach women whose attractiveness signals a good reproductive fitness, as men can produce more offspring than women can. To study gender differences in oxytocin’s effects on trust, Chapter 3 first reviews the literature on oxytocin, with a focus on gender differences in oxytocin’s effects. Then, it presents data from 144 participants (all singles with romantic interest in the opposite sex; 73 women during their luteal phase) who played the trust game after intranasal administration of oxytocin or placebo in a randomized, double-blind procedure. We find that oxytocin, compared to placebo, increased trust behavior to a larger degree in men than in women. Furthermore, this gender difference in oxytocin effects was more pronounced when participants interacted with unattractive and unthreatening interaction partners. We therefore demonstrate for the first time that there are gender differences in oxytocin’s effects on trust behavior towards potential romantic partners, and that this effect is dependent on facial features. Gender differences in the oxytocin system and its interaction with gonadal hormones might explain the gender-specific oxytocin effects on social approach behavior. Finally, Chapter 4 integrates the findings from both studies and provides a general discussion of gender differences in approach behavior both with and without oxytocin, as well as limitations and implications of this dissertation. Taken together, this dissertation reveals gender differences in the importance of facial attractiveness and threat, and in oxytocin’s effects when singles approach potential romantic partners. Future studies could utilize this refined version of the trust game to investigate oxytocin’s effect on approach behavior in homosexual participants, in friends, and in clinical samples like participants with social anxiety disorder or autism. Furthermore, our findings emphasize that more research including both genders is necessary to understand the mechanisms and evolutionary purpose of oxytocin’s effects on social cognition and behavior.
... This was the phase in which the computerised investor resumed a higher level of cooperation, following the second 'betrayal' phase in which the trustee received only small investments compared to the initial phase. Although it has been suggested that oxytocin may reduce betrayal aversion [2,52], females receiving oxytocin had significantly reduced trust repair following betrayal, but this effect was not found in males, such as included in our study [53]. Converging evidence shows that oxytocin does not appears to have solitary pro-social effects, but that the effect of oxytocin on human behavior is far more nuanced and also depends on environmental factors and personality traits [7]. ...
... Third, our sample consisted exclusively of young adult males and can therefore not be extrapolated to females. A previous study showed that the effect of oxytocin following betrayal on the Trust Game might be gender specific [53]. Fourth, we quantified baseline levels of trust using a questionnaire (Trust Inventory), independent of the Trust Game. ...
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Oxytocin has been proposed to enhance feelings of trust, however, these findings have been difficult to replicate. Environmental or hormonal factors might influence this association. We studied whether oxytocin moderates the association between the testosterone-cortisol ratio, which is associated with risk taking behavior and aggression, and trustworthiness, while controlling for the general level of trust. A randomized double-blind placebo-controlled study with 53 healthy males was performed in which 32IU oxytocin (n = 27) or placebo (n = 26) was administered intranasally. Participants subsequently played the Trust Game in which they were allocated to the role of trustee. In the third phase of the Trust Game, we found a positive association between the testosterone-cortisol-ratio and the proportion of the amount that is returned to the investor (P=<0.01). However, administration of oxytocin reduced reciprocity in those with a high testosterone-cortisol ratio after reciprocity restoration (a significant interaction effect between administration of oxytocin and the testosterone-cortisol ratio in the third phase of the Trust Game, P = 0.015). The third phase of the Trust Game represents the restoration of reciprocity and trustworthiness, after this is violated in the second phase. Therefore, our data suggest that oxytocin might hinder the restoration of trustworthiness and diminish risk-taking behavior when trust is violated, especially in those who are hormonally prone to risk-taking behavior by a high testosterone-cortisol ratio.
... Such a causal link between oxytocin and trust in humans, however, has not been corroborated in other research. Nave et al. (2015) reviewed six studies (Baumgartner et al., 2008;Barraza, 2010;Mikolajczak et al., 2010;Ebert et al., 2013;Klackl et al., 2013;Yao et al., 2014) in which unsuccessful attempts were made to replicate the results of Kosfeld et al. (2005). Although some of the details of the experiments in these studies were modifications of the original, the underlying principles were essentially the same: intranasal administration of oxytocin and a trust game. ...
... Even when we considered sensitivity to oxytocin, we did not detect significant difference in the mean average transfers between groups. These results are consistent with the results of many studies reporting that replication attempts were not successful (Baumgartner et al., 2008;Barraza, 2010;Mikolajczak et al., 2010;Ebert et al., 2013;Klackl et al., 2013;Yao et al., 2014). A novel framework for eliciting trust in humans is needed, even though the effect of oxytocin on trust really exists. ...
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There have been numerous studies in which the biological role of oxytocin in trusting behavior has been investigated. However, a link between oxytocin and trust in humans was discovered only in one early study. We hypothesized that there is a large interindividual variation in oxytocin sensitivity, and that such variation is one reason for the doubt surrounding the role of oxytocin in trusting behavior. Here, in a double-blind, prospective, case-control study, we administered intranasal oxytocin to participants of trust and risk games. We measured salivary oxytocin concentration, relating it to the amount of money transferred among participants (a proxy for trust) and the autism-spectrum quotient (AQ). A one-sided Fisher’s exact test was performed to detect differences between the oxytocin and placebo groups in the proportions of investors who transferred the maximum amount of money. We discovered a tendency for participants who received oxytocin to transfer higher amounts of money to co-participants than those who received a placebo ( P = 0.04). We also revealed a high degree of interindividual variation in salivary oxytocin concentrations after oxytocin administration. After stratifying the samples with respect to oxytocin sensitivity, oxytocin-sensitive participants in the oxytocin group also transferred higher amounts of money than those in the placebo group ( P = 0.03), while such a tendency was not observed for oxytocin-insensitive participants ( P = 0.34). Participants with lower AQ scores (less severe autistic traits) exhibited a greater tendency toward trusting behavior after oxytocin administration than did those with higher AQ scores ( P = 0.02). A two-sample t -test that was performed to detect significant differences in the mean transfers between the oxytocin and placebo groups indicated no significant between-group difference in the mean transfers ( P = 0.08). There are two possible interpretations of these results: First, there is no effect of oxytocin on trust in humans; second, the effects of oxytocin on trust in humans is person-dependent. However, the results should be interpreted with caution as the effect size was not larger than the minimal detectable effect size and the results were not statistically significant ( P > 0.05) after Bonferroni corrections.
... Furthermore, a number of studies have demonstrated that oxytocin can reduce limbic and brainstem responses to threatening face expressions in men (Kirsch et al., 2005;Quintana et al., 2016;Luo et al., 2017;Spengler et al., 2017;Kou et al., 2020), which could be of importance given our finding in healthy subjects that higher trait jealousy is associated with enhanced responses to angry faces in these and other regions . While some studies have reported that intranasal oxytocin can increase envy in non-romantic contexts (Shamay-Tsoory et al., 2009) and reduce forgiveness of trust betrayal in women but not men (Yao et al., 2014), these are in monetary gain/loss rather than relationship contexts. Two more recent studies have both demonstrated that intranasal can reduce jealousy ratings and/ or arousal ratings in response to imagined emotional or sexual infidelity by a heterosexual partner (Preckel et al., 2015;Zheng et al., 2021) and also in the context where jealousy is evoked by experiencing being excluded by a partner in an adaptation of the Cyberball game and playing instead with an attractive opposite sex stranger (Zheng et al., 2021). ...
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Romantic jealousy, especially in its pathological form, is a significant contributor to both domestic abuse, including partner sexual coercion and even murder, although relatively little research has been conducted on it. Both obsessive and delusional forms have been identified although only the latter is currently recognized as a pathological disorder. Studies in both clinical and healthy populations have identified altered fronto-striatal responsivity as being associated primarily with romantic jealousy and to date drug based treatments have targeted both dopaminergic and serotonergic systems. However, there is increasing interest in a potential role for the neuropeptide oxytocin, which can also modulate dopaminergic and serotonin systems in the brain and has been shown to altered in other psychotic conditions, such as schizophrenia and obsessive compulsive disorder. Recent studies in healthy populations have reported that when oxytocin is administered intranasally it can influence the brain to promote strengthening of romantic bonds and reduce romantic jealousy in both men and women evoked in either imagined or real contexts. These findings indicate a possible therapeutic use of intranasal oxytocin administration in pathological jealousy.
... This sexual asymmetry of OXT effects on gaze direction processing is consistent with previous findings (Yao et al. 2014;Yue et al. 2018). In the present study, OXT only improved women's capacity to detect the differences between direct and ambiguous averted gaze. ...
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Background Perceiving accurately that others are looking away from us (averted gaze) is as important, for social interactions, as perceiving that others are looking at us (direct gaze). However, previous studies have revealed that when the deflection angle of averted gaze is small, individuals tend to falsely perceive it as direct gaze. Oxytocin (OXT) has been shown to increase orientation to the eye region. Therefore, a critical question is whether and how OXT would facilitate the perception of ambiguous averted gaze.Objectives The present study aimed to measure the effects of OXT on the performance of males and females in distinguishing ambiguous averted gaze from direct gaze of different emotional faces.Methods In a double-blind placebo-controlled crossover experiment, 48 participants were presented successively two emotional faces with direct gaze (defined as 0, indicating the center of the eye) or averted gaze (defined as ±4, indicating the corner of the eye; +4 means that the iris moves 4 steps to the right; and −4 means that the iris moves 4 steps to the left) following intranasal oxytocin or placebo treatment and asked to make judgments on whether or not the two faces were the same in terms of identity. The interference effect of gaze direction was calculated by subtracting the mean accuracy and reaction time in the congruent gaze condition from those in the incongruent gaze condition. The logic of the measurement was if intranasal OXT would facilitate the detection of ambiguous averted gaze, we would observe a larger interference effect in the gaze incongruent condition compared with the gaze congruent condition, leading to longer RT or/and lower accuracy for identification judgment in the gaze incongruent condition.ResultsWhile there were no OXT effects in accuracy, we found a significant interaction between treatment, sex, and gaze congruency in reaction times. That is, following OXT as compared to placebo, women displayed stronger interference of gaze direction, whereas in men no significant difference was observed. Besides, this interaction did not vary across different emotional expressions.Conclusions Our findings provide the first evidence for sex-dependent effects of OXT on the perception of ambiguous averted gaze. Given potential therapeutic applications of OXT to patients with developmental and psychiatric disorders, who are characterized as atypical in encoding gaze features, the findings suggest that rather different treatment outcomes could be anticipated in males and females.
... The present study was further limited by our restriction of the analysis to men. Considering that Yao et al. 38 found oxytocin to induce prosocial behaviours in women but not men, future research should explore whether oxytocin has a negative effect on competitiveness in women. The need for such research is underscored by the specific role of oxytocin in female reproductive functions, such as in facilitating parturition and milk ejection during lactation 39,40 . ...
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Oxytocin-enhanced prosocial behaviour depends on individual characteristics. This study investigated the relationship between oxytocin and competitiveness, which is another important social trait and predicts economic and social outcomes. In this double-blind, randomized, and placebo-controlled study of 192 male participants, we examined whether oxytocin moderates competitiveness and whether the effect of oxytocin on competitiveness is amplified in individuals with autistic traits. While our results show no relationship between oxytocin and competitiveness, we observed suggestive patterns: albeit not significantly, oxytocin reduced and enhanced competitiveness among participants without autistic traits and among their counterparts with autistic traits, respectively.
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Various factors have been attributed to the inconsistent reproducibility of human oxytocin research in the cognitive and behavioral sciences. These factors include small sample sizes, a lack of pre-registered studies, and the absence of overarching theoretical frameworks that can account for oxytocin’s effects over a broad range of contexts. While there have been efforts to remedy these issues, there has been very little systematic scrutiny of the role of auxiliary assumptions, which are claims that are not central for testing a hypothesis but nonetheless critical for testing theories. For instance, the hypothesis that oxytocin increases the salience of social cues is predicated on the assumption that intranasally administered oxytocin increases oxytocin levels in the brain. Without robust auxiliary assumptions, it is unclear whether a hypothesis testing failure is due to an incorrect hypothesis or poorly supported auxiliary assumptions. Consequently, poorly supported auxiliary assumptions can be blamed for hypothesis failure, thereby safeguarding theories from falsification. In this article, I will evaluate the body of evidence for key auxiliary assumptions in human behavioral oxytocin research in terms of theory, experimental design, and statistical inference, and highlight assumptions that require stronger evidence. Strong auxiliary assumptions will leave hypotheses vulnerable for falsification, which will improve hypothesis testing and consequently advance our understanding of oxytocin’s role in cognition and behavior.
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Trust is essential for establishing and maintaining cooperative behaviors between individuals and institutions in a wide variety of social, economic, and political contexts. This book explores trust through the lens of neurobiology, focusing on empirical, methodological, and theoretical aspects. Written by a distinguished group of researchers from economics, psychology, human factors, neuroscience, and psychiatry, the chapters shed light on the neurobiological underpinnings of trust as applied in a variety of domains. Researchers and students will discover a refined understanding of trust by delving into the essential topics in this area of study outlined by leading experts.
Chapter
The neuropeptide oxytocin (OXT) has been linked to interpersonal trust. While initial behavioral studies demonstrated a facilitating effect of OXT on trusting behavior, more recently these findings have been challenged. In this chapter we review the literature reporting two approaches that are used to evaluate OXT’s effects: exogenous OXT administration and the investigation of the endogenous OXT system. With respect to trust, we report results from studies investigating trusting behavior, mostly using economic games, and studies looking on the intention to trust other individuals. Overall, clear evidence for a direct trust-promoting effect of OXT as proposed by early studies cannot be found. Instead, there is evidence that the relationship between OXT and trust is modulated by manifold contextual factors that are closely interrelated, e.g., social affiliation, personality traits, gender, mental disorders, and genetic disposition. Furthermore, it could be argued that the effect of OXT on trust is not a specific one but only a subphenomenon of the more general prosocial effect of the neuropeptide. Future research should aim to conceive models of the OXT–trust connection considering the interactions between genes, brain functioning, and the environment, advancing the knowledge of understanding interpersonal trust.
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The hormones oxytocin, vasopressin, and testosterone have been implicated in cooperative behaviours and have attracted increasing research interest for their potential to regulate human cooperation in both healthy and clinical populations. However, the behavioural effects of the administration of these hormones remain to be verified. The current analysis included 41 studies involving 3,269 participants with a narrow age range. We examined the administration effects of these hormones on cooperative behaviour and the regulatory effects of individual characteristics, hormone interventions, and task structure and context. Results revealed a moderate positive effect size of oxytocin intranasal administration, a large negative effect size of vasopressin intranasal administration, and nonsignificant effects of testosterone administration on cooperative behaviours. Participants with mental dysfunctions were less sensitive to oxytocin and vasopressin administration. Oxytocin administration was effective in an in-group situation and for initial choices, corroborating a Tit-for-Tat strategy.
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Previous studies have shown that when a recipient suffers from financial harm, allocators can use repair strategies that address financial or relational interests to promote relationship repair. Research to date, however, has neglected to study the effects of financial and relational strategies on relationship preservation simultaneously. In the present contribution, we examine this question. Based on the equality norm, we hypothesized that a financial compensation that fails to redress the harm suffered by the recipient (i.e., undercompensation) will be less effective in preserving a relationship than a financial compensation that do redress it (i.e., equal compensation and overcompensation). Moreover, we expected that relational strategies (i.e., apologies) would promote relationship preservation in contexts where the financial compensation alone is insufficient to redress the harm to the recipient, thus in cases of undercompensation. The results of a pilot study and a lab experiment using the dictator game confirmed our hypotheses. Consequently, our studies demonstrate that even in purely economic settings, relational strategies (i.e., apologies) can facilitate relationship preservation over and above financial strategies (i.e., financial compensation).
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