Neural asymmetry in aligning with generous versus selfish descriptive norms in a charitable donation task.

Social alignment is supported by the brain's reward system (ventral striatum), presumably because attaining synchrony generates feelings of connectedness. However, this may hold only for aligning with generous others, while aligning with selfishness might threaten social connectedness. We investigated this postulated asymmetry in an incentivized fMRI charitable donation task. Participants decided how much of their endowment to donate to real charities, and how much to keep for themselves. Compared to a baseline condition, donations significantly increased or decreased in function of the presence of descriptive norms. The fMRI data reveal that processing selfish norms (more than generous ones) recruited the amygdala and anterior insula. Aligning with selfish norms correlated on average with reduced activity in the lateral prefrontal cortex (LPFC) and, at the individual level, with decreasing activity in the ventral striatum (VS). Conversely, as participants aligned more with generous norms, they showed increasing activity in the LPFC and, on average, increased activity in the VS. This increase occurred beyond the increased VS activity which was also observed in the baseline condition. Taken together, this suggests that aligning with generosity, while effortful, provides a "warm glow of herding" associated with collective giving, but that aligning with selfishness does not.

A registered replication study on oxytocin and trust.

In an influential paper, Kosfeld et al. (2005) showed that intranasal administration of oxytocin (OT) increases the transfers made by investors in the trust game-suggesting that OT increases trust in strangers. Subsequent studies investigating the role of OT in the trust game found inconclusive effects on the trusting behaviour of investors but these studies deviated from the Kosfeld et al. study in an important way-they did not implement minimal social contact (MSC) between the investors and the trustees in the trust game. Here, we performed a large double-blind and placebo-controlled replication study of the effects of OT on trusting behaviour that yields a power of more than 95% and implements an MSC condition as well as a no-social-contact (NoC) condition. We find no effect of OT on trusting behaviour in the MSC condition. Exploratory post hoc analyses suggest that OT may increase trust in individuals with a low disposition to trust in the NoC condition, but this finding requires confirmation in future research. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 19 October 2018. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.11980368.

A functional MRI study on how oxytocin affects decision making in social dilemmas: Cooperate as long as it pays off, aggress only when you think you can win.

We investigate if the neuropeptide oxytocin (OT), known to moderate social behaviour, influences strategic decision making in social dilemmas by facilitating the integration of incentives and social cues. Participants (N=29) played two economic games with different incentive structures in the fMRI scanner after receiving OT or placebo (following a double blind, within-subject design). Pictures of angry or neutral faces (the social cues) were displayed alongside the game matrices. Consistent with a priori hypotheses based on the modulatory role of OT in mesolimbic dopaminergic brain regions, the results indicate that, compared to placebo, OT significantly increases the activation of the nucleus accumbens during an assurance (coordination) game that rewards mutual cooperation. This increases appetitive motivation so that cooperative behaviour is facilitated for risk averse individuals. OT also significantly attenuates the amygdala, thereby reducing the orienting response to social cues. The corresponding change in behaviour is only apparent in the chicken (or anti-coordination) game, where aggression is incentivized but fatal if the partner also aggresses. Because of this ambiguity, decision making can be improved by additional information, and OT steers decisions in the chicken game in accordance with the valence of the facial cue: aggress when face is neutral; retreat when it is angry. Through its combined influence on amygdala and nucleus accumbens, OT improves the selection of a cooperative or aggressive strategy in function of the best match between the incentives of the game and the social cues present in the decision environment.

Trust as commodity: social value orientation affects the neural substrates of learning to cooperate.

Individuals differ in their motives and strategies to cooperate in social dilemmas. These differences are reflected by an individual's social value orientation: proselfs are strategic and motivated to maximize self-interest, while prosocials are more trusting and value fairness. We hypothesize that when deciding whether or not to cooperate with a random member of a defined group, proselfs, more than prosocials, adapt their decisions based on past experiences: they 'learn' instrumentally to form a base-line expectation of reciprocity. We conducted an fMRI experiment where participants (19 proselfs and 19 prosocials) played 120 sequential prisoner's dilemmas against randomly selected, anonymous and returning partners who cooperated 60% of the time. Results indicate that cooperation levels increased over time, but that the rate of learning was steeper for proselfs than for prosocials. At the neural level, caudate and precuneus activation were more pronounced for proselfs relative to prosocials, indicating a stronger reliance on instrumental learning and self-referencing to update their trust in the cooperative strategy.

Sexual dimorphism in oxytocin responses to health perception and disgust, with implications for theories on pathogen detection.

In response to a recent hypothesis that the neuropeptide oxytocin might be involved in human pathogen avoidance mechanisms, we report the results of a study in which we investigate the effect of intranasal oxytocin on two behaviors serving as proxies for pathogen detection. Participants received either oxytocin or a placebo and were asked to evaluate (1) the health of Caucasian male computer-generated pictures that varied in facial redness (an indicator of hemoglobin perfusion) and (2) a series of pictures depicting disgusting scenarios. Men, but not women, evaluated all faces, regardless of color, as less healthy when given oxytocin compared to a placebo. Women, on the other hand, expressed decreased disgust when given oxytocin compared to a placebo. These results suggest that intranasal oxytocin administration does not facilitate pathogen detection based on visual cues, but instead reveal clear sex differences in the perception of health and sickness cues.

Oxytocin does not make a face appear more trustworthy but improves the accuracy of trustworthiness judgments.

Previous research on the relation between oxytocin and trustworthiness evaluations has yielded inconsistent results. The current study reports an experiment using artificial faces which allows manipulating the dimension of trustworthiness without changing factors like emotions or face symmetry. We investigate whether (1) oxytocin increases the average trustworthiness evaluation of faces (level effect), and/or whether (2) oxytocin improves the discriminatory ability of trustworthiness perception so that people become more accurate in distinguishing faces that vary along a gradient of trustworthiness. In a double blind oxytocin/placebo experiment (N=106) participants conducted two judgement tasks. First they evaluated the trustworthiness of a series of pictures of artificially generated faces, neutral in the trustworthiness dimension. Next they compared neutral faces with artificially generated faces that were manipulated to vary in trustworthiness. The results indicate that oxytocin (relative to a placebo) does not affect the evaluation of trustworthiness in the first task. However, in the second task, misclassification of untrustworthy faces as trustworthy occurred significantly less in the oxytocin group. Furthermore, oxytocin improved the discriminatory ability of untrustworthy, but not trustworthy faces. We conclude that oxytocin does not increase trustworthiness judgments on average, but that it helps people to more accurately recognize an untrustworthy face.

The effect of oxytocin on cooperation in a prisoner's dilemma depends on the social context and a person's social value orientation.

The interactionist approach to the study of exogenous oxytocin (OT) effects on prosocial behavior has emphasized the need to consider both contextual cues and individual differences. Therefore, an experiment was set up to examine the joint effect of intranasal OT, a salient social cue and the personality trait social value orientation on cooperative behavior in one-shot prisoner's dilemma games. The outcome of these mixed-motive games is known to be highly dependent on values and on social information that might reveal the partner's intent. Consistent with an a priori hypothesis, OT and social information interact significantly to affect the behavior of individuals with a proself value orientation: after prior contact with the game partner, OT enhances cooperative behavior, whereas in anonymous conditions, it exacerbates their intrinsic self-interested behavior. These effects of OT do not hold for individuals with a prosocial value orientation, whose cooperation levels appear to be more influenced by prior contact with the game partner. Follow-up hypotheses for why prosocial and proself individuals respond differently to exogenous OT were developed.

Establishing cooperation in a mixed-motive social dilemma. An fMRI study investigating the role of social value orientation and dispositional trust.

When people are confronted with social dilemmas, their decision-making strategies tend to be associated with individual social preferences; prosocials have an intrinsic willingness to cooperate, while proselfs need extrinsic motivators signaling personal gain. In this study, the biological roots for the proselfs/prosocials concept are explored by investigating the neural correlates of cooperative versus defect decisions when participants engage in a series of one-shot, anonymous prisoner's dilemma situations. Our data are in line with previous studies showing that prosocials activate several social cognition regions of the brain more than proselfs (here: medial prefrontal cortex, temporo-parietal junction, and precuneus BA 7 (Brodmann area 7), and that dispositional trust positively affects prosocials' decisions to cooperate. At the neural level, however, dispositional trust appears to exert a greater marginal effect on brain activity of proselfs in three social cognition regions, which does not translate into an increase in cooperation. An event-related analysis shows that cooperating prosocials show significantly more activation in the precuneus (BA 7) than proselfs. Based on previous research, we interpret this result to be consistent with prosocials' enhanced tendency to infer the intentions of others in social dilemma games, and the importance of establishing norm congruence when they decide to cooperate.

When do people cooperate? The neuroeconomics of prosocial decision making.

Understanding the roots of prosocial behavior is an interdisciplinary research endeavor that has generated an abundance of empirical data across many disciplines. This review integrates research findings from different fields into a novel theoretical framework that can account for when prosocial behavior is likely to occur. Specifically, we propose that the motivation to cooperate (or not), generated by the reward system in the brain (extending from the striatum to the ventromedial prefrontal cortex), is modulated by two neural networks: a cognitive control system (centered on the lateral prefrontal cortex) that processes extrinsic cooperative incentives, and/or a social cognition system (including the temporo-parietal junction, the medial prefrontal cortex and the amygdala) that processes trust and/or threat signals. The independent modulatory influence of incentives and trust on the decision to cooperate is substantiated by a growing body of neuroimaging data and reconciles the apparent paradox between economic versus social rationality in the literature, suggesting that we are in fact wired for both. Furthermore, the theoretical framework can account for substantial behavioral heterogeneity in prosocial behavior. Based on the existing data, we postulate that self-regarding individuals (who are more likely to adopt an economically rational strategy) are more responsive to extrinsic cooperative incentives and therefore rely relatively more on cognitive control to make (un)cooperative decisions, whereas other-regarding individuals (who are more likely to adopt a socially rational strategy) are more sensitive to trust signals to avoid betrayal and recruit relatively more brain activity in the social cognition system. Several additional hypotheses with respect to the neural roots of social preferences are derived from the model and suggested for future research.

The cognitive demands on cooperation in social dilemmas: an fMRI study.

This study uses fMRI to investigate the cognitive demands of decision-making in two types of cooperation games: a prisoner's dilemma (PD) eliciting a temptation to free-ride, leading to a dominant, self-interested response, and a stag hunt (SH) that has no dominant response but offers pay-off incentives that make mutual cooperation collectively beneficial but risky. Consequently, the PD poses greater conflict between self- and collective interest, greater demands for computational reasoning to derive the optimal solution, and greater demands for mentalizing to infer the intentions of others. Consistent with these differences between the two games, the results indicate that the PD is associated with increased activity in the anterior cingulate gyrus, prefrontal cortex, parietal lobe, and temporoparietal junction. With less conflict, the demands for computation and mentalizing are reduced in the SH, and cooperation levels increase dramatically. The differences in brain activation elicited by the different incentive structures of the PD and the SH appear to be independent of individual differences in revealed social preferences.

Oxytocin and cooperation under conditions of uncertainty: the modulating role of incentives and social information.

The neuropeptide Oxytocin (OT) has been implicated in many aspects of mammalian social behavior. This study investigates how OT interacts with two well-studied determinants of cooperative behavior: incentives and social information. Participants received OT or a placebo and played two economic games: a Coordination Game (with strong incentives to cooperate) and a Prisoner's Dilemma (with weak cooperative incentives). OT enhanced cooperation only when social information was present, and this effect was significantly more pronounced in the Coordination Game. When social information was lacking, OT surprisingly decreased cooperation. Consistent with the well-established role of OT in trust-building and in social cognition, social information appears to be crucial for OT to boost cooperative expectations in an interdependent social interaction that provides incentives to cooperate. When these cues are absent, OT appears to instead elicit a risk-averse strategy.

Social value orientation: related to empathy and the ability to read the mind in the eyes.

This study explores correlates of social value orientation, a personality trait that reflects a stable individual difference in the way people evaluate outcomes for themselves and others in situations of interdependence. Previous findings (e.g., the triangle hypothesis) have indicated that people with a prosocial orientation tend to view their interacting partners as having heterogeneous social motives, whereas people with a proself orientation tend to believe all people are alike and selfish. Consistent with this idea that people vary in their perception of other's social motives, the data in this study indicate that a prosocial orientation correlated positively with the ability to adopt another person's point of view and infer mental states from eye gazes. These social skills correlated negatively with an individualistic orientation.

Spontaneous Eye Blink Rates vary according to individual differences in generalized control perception.

This study tested the hypothesis that individual differences in generalized control perception for 43 undergraduate adults may be reflected in Spontaneous Eye Blink Rates during conversation in an interview. Control perception was assessed by means of Rotter's internal-external Locus of Control questionnaires, while Spontaneous Eye Blink Rates were computed from filmed videos of interviews consisting of a series of questions which could presumably have triggered different mental states. Pearson correlations and linear regression analyses indicated that the individual differences in Spontaneous Eye Blink Rates did not differ significantly across different questions, but that Spontaneous Eye Blink Rates measured over the entire interview correlated positively and significantly with an internal Locus of Control (r = .26). This could be interpreted as modest but corroborative evidence that a personality trait reflecting control perception may have a biological component. The possible roles of dopamine neurotransmission and frontal cortex involvement in higher cognition and Locus of Control are discussed.

On feeling in control: a biological theory for individual differences in control perception.

This review aims to create a cross-disciplinary framework for understanding the perception of control. Although, the personality trait locus of control, the most common measure of control perception, has traditionally been regarded as a product of social learning, it may have biological antecedents as well. It is suggested that control perception follows from the brain's capacity for self regulation, leading to flexible and goal directed behaviours. To this account, a model is presented which spans several levels of analyses. On a behavioural level, control perception may be a corollary of emotion regulation, executive functions, and social cognition. On a neural level, these self-regulatory functions are substantiated in part by the dorsolateral and ventral prefrontal cortex and the anterior cingulate cortex. In addition, a possible role of subcortical-cortical dopamine pathways underlying control perception is discussed.

Tonic and phasic activation and arousal effects as a function of feedback in repetitive-choice reaction time tasks.

This study examines the effects of positive and negative feedback on performance during choice reaction time tasks to assess whether they differentially affect phasic arousal and tonic activation. Participants (N = 96) received either no feedback or signals of reward, punishment, or both during a semantic and a visuospatial repetitive-choice reaction time task. The number of errors made was analyzed both on a trial-by-trial basis and over a continuous series of 80 trials (assessing phasic and tonic feedback effects, respectively). The results show that punishment and reward have different phasic and tonic effects on performance. The data further show that feedback effects interact with the task characteristics: semantic versus visuospatial, and reaction stimulus preceded by a warning signal versus an irrelevant signal. The interaction effects appear to be consistent with the proposed neurological model.