Toko Kiyonari

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 Prisoners 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.

THE SOCIAL EXCHANGE HEURISTIC MANAGING ERRORS IN SOCIAL EXCHANGE

We extend the logic of Haselton and Busss (2000) error management theory to the domain of social exchange and propose that a psychological mechanism, referred to as the social exchange heuristic (SEH), produces certain cognitive biases that affect how individuals manage these errors. We predicted that the SEH would remain dormant in individuals who failed to realize that they were in a situation that involved social exchange. In the first experiment (n = 78), PD players who had a chance, before they played the game, to think both about the nature of the game they were playing and about their partners choice were less cooperative compared to players of the standard one-shot PDG. In the second experiment (n = 105), PD players were again less cooperative when they made their decision before they were matched with a particular partner than after they had been matched with a partner. Results strongly suggest the operation of a SEH.

In Search of Homo economicus

Homo economicus, a model for humans in neoclassical economics, is a rational maximizer of self-interest. However, many social scientists regard such a person as a mere imaginary creature. We found that 31 of 446 residents of relatively wealthy Tokyo suburbs met the behavioral definition of Homo economicus. In several rounds of economic games, participants whose behavior was consistent with this model always apportioned the money endowed by the experimenter to themselves, leaving no share for their partners. These participants had high IQs and a deliberative decision style. An additional 39 participants showed a similar disregard for other people’s welfare, although they were slightly more altruistic than those in the Homo economicus group. The psychological composition of these quasi–Homo economicus participants was distinct from that of participants in the Homo economicus group. Although participants in the latter group behaved selfishly on the basis of rational calculations, those in the former group made selfish choices impulsively. The implications of these findings concerning the two types of extreme noncooperators are discussed.

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 prisoners 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 partners 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.

Inducing Cooperative Behavior among Proselfs versus Prosocials: The Moderating Role of Incentives and Trust

This study investigates how an individual’s social value orientation (SVO) interacts with explicit cooperative incentives on one hand, and intrinsic and extraneously induced trust on the other hand, to affect cooperative behavior. In three experiments, subjects (n = 322) played a one-shot prisoner’s dilemma (PD; with weak cooperative incentives) and an assurance game (AG; with strong cooperative incentives) in conditions with or without trust signals. The authors found, as expected, that cooperative behavior is strongly spurred by explicit incentives, but not by trust, among people with a proself value orientation. Conversely, trust is very important to enhance cooperative behavior of participants with a prosocial value orientation, whereas explicit incentives are less important compared to proselfs. The authors conclude that this study reveals two fundamentally different logics of cooperative behavior: one based on extrinsic incentives and the other on trust.

Does Trust Beget Trustworthiness? Trust and Trustworthiness in Two Games and Two Cultures: A Research Note.

An important unanswered question in the empirical literature on trust is whether trusting begets trustworthiness. In two experimental games, with Japanese and American participants, respectively, we compared trust and trustworthiness to provide an answer to this question. The trustee in the standard Trust Game knows that he or she is trusted, whereas the trustee in the Faith Game does not know whether or not this is the case. Except for this fact, the trustee faces the same choice in both situations. If the simple fact that one is trusted by someone else makes a person more trustworthy to the truster, then the trustee in the Trust Game should behave in a more trustworthy manner. Our results indicate that trust does not beget trustworthiness, at least in one-shot games. The results also indicate that trust and trustworthiness are two sides of the same coin but are quite distinct, partially replicating the recent findings of Buchan, Croson, and Dawes. American trusters were more trusting than their Japanese counterparts in the Trust Game, whereas American trustees were less trustworthy. The nationality difference in trust and trustworthiness is less pronounced in the Faith Game. We conclude that trust researchers should consider the limitations of one-shot games in studying the determinants of trust and trustworthiness.

Representation of economic preferences in the structure and function of the amygdala and prefrontal cortex

Social value orientations (SVOs) are economic preferences for the distribution of resources – prosocial individuals are more cooperative and egalitarian than are proselfs. Despite the social and economic implications of SVOs, no systematic studies have examined their neural correlates. We investigated the amygdala and dorsolateral prefrontal cortex (DLPFC) structures and functions in prosocials and proselfs by functional magnetic resonance imaging and evaluated cooperative behavior in the Prisoner’s Dilemma game. We found for the first time that amygdala volume was larger in prosocials and positively correlated with cooperation, while DLPFC volume was larger in proselfs and negatively correlated with cooperation. Proselfs’ decisions were marked by strong DLPFC and weak amygdala activity, and prosocials’ decisions were marked by strong amygdala activity, with the DLPFC signal increasing only in defection. Our findings suggest that proselfs’ decisions are controlled by DLPFC-mediated deliberative processes, while prosocials’ decisions are initially guided by automatic amygdala processes.

Response time in economic games reflects different types of decision conflict for prosocial and proself individuals

Significance Prosocial and proself predispositions dictate economic game players’ fast decisions but exert limited influence when game players take a longer time in making decisions. Prosocially predisposed individuals use the extended time to contemplate the risk of being exploited. Selfishly predisposed individuals are suggested to behave according to the immediate incentives of the games when they make decisions quickly and become behaviorally less selfish as they spend more time assessing the long-term strategic implications of always behaving according to immediate incentives. Different strategies are needed to promote prosocial behavior and to design institutions depending on the constitution of the population. Behavioral and neuroscientific studies explore two pathways through which internalized social norms promote prosocial behavior. One pathway involves internal control of impulsive selfishness, and the other involves emotion-based prosocial preferences that are translated into behavior when they evade cognitive control for pursuing self-interest. We measured 443 participants’ overall prosocial behavior in four economic games. Participants’ predispositions [social value orientation (SVO)] were more strongly reflected in their overall game behavior when they made decisions quickly than when they spent a longer time. Prosocially (or selfishly) predisposed participants behaved less prosocially (or less selfishly) when they spent more time in decision making, such that their SVO prosociality yielded limited effects in actual behavior in their slow decisions. The increase (or decrease) in slower decision makers was prominent among consistent prosocials (or proselfs) whose strong preference for prosocial (or proself) goals would make it less likely to experience conflict between prosocial and proself goals. The strong effect of RT on behavior in consistent prosocials (or proselfs) suggests that conflict between prosocial and selfish goals alone is not responsible for slow decisions. Specifically, we found that contemplation of the risk of being exploited by others (social risk aversion) was partly responsible for making consistent prosocials (but not consistent proselfs) spend longer time in decision making and behave less prosocially. Conflict between means rather than between goals (immediate versus strategic pursuit of self-interest) was suggested to be responsible for the time-related increase in consistent proselfs’ prosocial behavior. The findings of this study are generally in favor of the intuitive cooperation model of prosocial behavior.

No place to hide: When shame causes proselfs to cooperate

Shame is considered a social emotion with action tendencies that elicit socially beneficial behavior. Yet, unlike other social emotions, prior experimental studies do not indicate that incidental shame boosts prosocial behavior. Based on the affect as information theory, we hypothesize that incidental feelings of shame can increase cooperation, but only for self-interested individuals, and only in a context where shame is relevant with regards to its action tendency. To test this hypothesis, cooperation levels are compared between a simultaneous prisoners dilemma (where “defect” may result from multiple motives) and a sequential prisoners dilemma (where “second player defect” is the result of intentional greediness). As hypothesized, shame positively affected proselfs in a sequential prisoners dilemma. Hence ashamed proselfs become inclined to cooperate when they believe they have no way to hide their greediness, and not necessarily because they want to make up for earlier wrong-doing.

Sexually dimorphic preference for altruism in the opposite sex according to recipient.

Sexual selection may affect human altruistic behaviour. Evolutionary psychology predicts that human mate preference reflects sexual selection. We investigated sex differences in preference for opposite-sex altruism according to recipient because the reasons for altruistic behaviour differ according to the relationship between actor and recipient. We employed the Self-Report Altruism Scale Distinguished by the Recipient, which was newly developed to evaluate altruism among Japanese undergraduates. We asked participants to evaluate preferences for each item based on the recipient of the altruistic behaviour (family members, friends or acquaintances, and strangers). Preference for opposite-sex altruism differed according to recipient, gender of the participant, and relationship type, and several significant interactions were observed among these factors. We suggest that whereas women use a potential partners altruism towards strangers as a costly signal of their resource-holding potential when choosing a mate, they consider altruism towards family when they are in a long-term relationship to ensure that resources are not allocated to non-relatives.