Social high performers under stress behave more prosocially and detect happy emotions better in a male sample.

Psychosocial stress is increasing in society, impacting our lives in all social domains. However, the conditions under which stress facilitates ("tend-and-befriend") or hinders ("fight-or-flight") social approach remain elusive. We tested whether previous heterogeneous findings might be resolved by accounting for individual differences in social performance under stress. For that purpose, we introduce the novel Trier Social Stress Test (TSST) social performance index that was aggregated across ratings from two independent observers. Moreover, we apply an innovative setup enabling electroencephalographic (EEG) data to be measured inside an electrically-shielded cabin during stress, namely the TSST-EEG. Relying on a sample of 59 healthy male participants, we collected behavioral (i.e., sharing resources with others) and cognitive (i.e., detecting facial emotional expressions) approach patterns while participants experienced either acute psychosocial stress (n = 31) or no stress (control condition; n = 28) and while EEG was being recorded. During stress exposure, high-performing participants behaved more prosocially, and differentiated better between happy and neutral emotions on both behavioral and neurophysiological levels (revealed by intensity differences in a N170-like response). Overall, our findings demonstrate the added value of both the novel TSST social performance index and the novel TSST-EEG setup. By showing that high social performance during the TSST is associated with behavioral, cognitive, and neurophysiological approach patterns, our study offers valuable insights into adaptive or maladaptive psychobiological mechanisms in coping with psychosocial stress. Future stress research should address the role of social performance differences during stress in social interaction to better understand the behavioral consequences of psychosocial stress in humans.

Oxytocin has sex-specific effects on trust and underlying neurophysiological processes.

The neuropeptide oxytocin (OT) regulates mammalian social approach behavior across sexes. Yet most OT studies in humans exclusively investigated men. Here, we studied sex differences in OT's effects on human trust behavior in 144 heterosexual participants (73 women, 71 men). Participants received 24 international units of intranasal OT or placebo treatment and played a trust game in the role of the investor while undergoing electroencephalography. Trustees were represented by photos of the other sex gradually varying in their pre-rated intensities of facial features signaling attractiveness and threat. On a behavioral level, we observed that OT increased trust in men and reduced it in women when trustees showed weak signals of attractiveness and threat. Correspondingly, on the neurophysiological level, we noted that OT intensified the P100 in male participants, but dampened it in female ones. Our findings demonstrate OT's sex- and context-specific effects on social approach behavior and an underlying early visual attention-related brain process. This evidence demonstrates the need to consider psychobiological mechanisms of sexual dimorphism in human OT research.

Facial threat affects trust more strongly than facial attractiveness in women than it does in men.

Trust is essential in initiating social relationships. Due to the differential evolution of sex hormones as well as the fitness burdens of producing offspring, evaluations of a potential mating partner's trustworthiness likely differ across sexes. Here, we explore unknown sex-specific effects of facial attractiveness and threat on trusting other-sex individuals. Ninety-three participants (singles; 46 women) attracted by the other sex performed an incentivized trust game. They had to decide whether to trust individuals of the other sex represented by a priori-created face stimuli gradually varying in the intensities of both attractiveness and threat. Male and female participants trusted attractive and unthreatening-looking individuals more often. However, whereas male participants' trust behavior was affected equally by attractiveness and threat, female participants' trust behavior was more strongly affected by threat than by attractiveness. This indicates that a partner's high facial attractiveness might compensate for high facial threat in male but not female participants. Our findings suggest that men and women prioritize attractiveness and threat differentially, with women paying relatively more attention to threat cues inversely signaling parental investment than to attractiveness cues signaling reproductive fitness. This difference might be attributable to an evolutionary, biologically sex-specific decision regarding parental investment and reproduction behavior.

Victory is its own reward: oxytocin increases costly competitive behavior in schizophrenia.

BACKGROUND: Aberrant sensitivity to social reward may be an important contributor to abnormal social behavior that is a core feature of schizophrenia. The neuropeptide oxytocin impacts the salience of social information across species, but its effect on social reward in schizophrenia is unknown. METHODS: We used a competitive economic game and computational modeling to examine behavioral dynamics and oxytocin effects on sensitivity to social reward among 39 men with schizophrenia and 54 matched healthy controls. In a randomized, double-blind study, participants received one dose of oxytocin (40 IU) or placebo and completed a 35-trial Auction Game that quantifies preferences for monetary v. social reward. We analyzed bidding behavior using multilevel linear mixed models and reinforcement learning models. RESULTS: Bidding was motivated by preferences for both monetary and social reward in both groups, but bidding dynamics differed: patients initially overbid less compared to controls, and across trials, controls decreased their bids while patients did not. Oxytocin administration was associated with sustained overbidding across trials, particularly in patients. This drug effect was driven by a stronger preference for winning the auction, regardless of monetary consequences. Learning rate and response variability did not differ between groups or drug condition, suggesting that differences in bidding derive primarily from differences in the subjective value of social rewards. CONCLUSIONS: Our findings suggest that schizophrenia is associated with diminished motivation for social reward that may be increased by oxytocin administration.