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Concept: Dictator game


The strong reciprocity model of the evolution of human cooperation has gained some acceptance, partly on the basis of support from experimental findings. The observation that unfair offers in the ultimatum game are frequently rejected constitutes an important piece of the experimental evidence for strong reciprocity. In the present study, we have challenged the idea that the rejection response in the ultimatum game provides evidence of the assumption held by strong reciprocity theorists that negative reciprocity observed in the ultimatum game is inseparably related to positive reciprocity as the two sides of a preference for fairness. The prediction of an inseparable relationship between positive and negative reciprocity was rejected on the basis of the results of a series of experiments that we conducted using the ultimatum game, the dictator game, the trust game, and the prisoner’s dilemma game. We did not find any correlation between the participants' tendencies to reject unfair offers in the ultimatum game and their tendencies to exhibit various prosocial behaviors in the other games, including their inclinations to positively reciprocate in the trust game. The participants' responses to postexperimental questions add support to the view that the rejection of unfair offers in the ultimatum game is a tacit strategy for avoiding the imposition of an inferior status.

Concepts: Game theory, Hypothesis, The Evolution of Cooperation, Prisoner's dilemma, Dictator game, Ultimatum game, Experimental economics, Reciprocity


This study investigated whether children with autism spectrum disorder (ASD) and typically developing children matched on receptive language share resources fairly and reciprocally. Children completed age-appropriate versions of the Ultimatum and Dictator Games with real stickers and an interactive partner. Both groups offered similar numbers of stickers (preferring equality over self-interest), offered more stickers in the Ultimatum Game, and verbally referenced ‘fairness’ at similar rates. However, children with ASD were significantly more likely to accept unfair offers and were significantly less likely to reciprocate the puppet’s offers. Failure to reciprocate fair sharing may significantly impact on social cohesion and children’s ability to build relationships. These important differences may be linked to broader deficits in social-cognitive development and potentially self-other understanding.

Concepts: Sociology, Autism, Pervasive developmental disorder, Asperger syndrome, Autism spectrum, PDD-NOS, Dictator game, Accept


We exploit the fact that generosity and trustworthiness are highly correlated and the former can thus be a sign of the latter. Subjects decide between a generous and a mean split in a dictator game. Some of them are informed from the start that afterwards they will participate in a trust game and that their choice in the dictator game may matter; others are not informed in advance. In the trust game, before trusters decide whether or not to trust, some trustees can reveal (or conceal) only their true choice in the dictator game, while others can say to trusters, truthfully or otherwise, what they chose. We find that a generous choice made naturally by uninformed trustees and reliably revealed is more effective in persuading trusters to trust than a generous choice that could be strategic or a lie. Moreover, we find that, when they can, mean subjects lie and go on to be untrustworthy.

Concepts: Game theory, Virtue, Social psychology, Dictator game, Ultimatum game


Psychopathic personality traits are linked with selfish and non-cooperative responses during economical decision making games. However, the possibility that these responses may vary when responding to members of the in-group and the out-group has not yet been explored. We aimed to examine the effects of primary (selfish, uncaring) and secondary (impulsive, irresponsible) psychopathic personality traits on the responses of non-offending participants to the in-group and the out-group (defined in terms of affiliation to a UK University) across a series of economical decision making games. We asked a total of 60 participants to act as the proposer in both the dictator game and the ultimatum game. We found that across both tasks, those who scored highly for secondary psychopathic traits showed an elevated intergroup bias, making more generous offers toward members of the in-group relative to the out-group. An exaggerated intergroup bias may therefore represent a motivational factor for the antisocial behavior of those with elevated secondary psychopathic traits.

Concepts: Game theory, Abnormal psychology, Antisocial personality disorder, Conduct disorder, Psychopathy, Dictator game, Personality disorders, Narcissism


Impairments in social functioning are a common feature of psychiatric disorders. Game paradigms pose a unique way for studying how people make decisions in interpersonal contexts. In the last decade, researchers have started to use these paradigms to study social decision-making in patients with psychiatric disorders.

Concepts: Game theory, Psychology, Medicine, Sociology, Mental disorder, Psychiatry, Dictator game, Subgame perfect equilibrium



The accumulation of findings that most responders in the ultimatum game reject unfair offers provides evidence that humans are driven by social preferences such as preferences for fairness and prosociality. On the other hand, if and how the proposer’s behavior is affected by social preferences remains unelucidated. We addressed this question for the first time by manipulating the knowledge that the proposer had about the responder’s belief concerning the intentionality of the proposer. In a new game called the “ultimatum game with ambiguous intentions of the proposer (UGAMB),” we made the intentionality of the proposer ambiguous to the recipient. We expected and found that the proposer would make more unfair offers in this new game than in the standard ultimatum game. This expectation can be derived from either the preference-based model or the strategy model of the proposer’s giving decision. The additional finding that more unfair giving in the UGAMB was not mediated by the proposer’s expectation that the recipient would be more willing to accept unfair offers provided support for the preference-based model. Using a psychological measure of cognitive control, the preference-based model received additional support through a conceptual replication of the previous finding that cognitive control of intuitive drive for prosociality in the dictator game, rather than mind reading in the ultimatum game, is responsible for the difference in giving between the two games.

Concepts: Game theory, Psychology, Mind, Thought, Utility, Dictator game, Ultimatum game, Experimental economics


The design of effective donor recruitment campaigns requires an accurate understanding of donor motivations. This requires cross-validation of theoretically derived, psychometrically assessed motivations with behavioural preferences. Theoretical models suggest that blood donors should be more sensitive than nondonors to violations of fairness norms. Specifically, active blood donors, compared to nondonors, should endorse beliefs of reciprocal fairness, norms of both positive and negative reciprocity and reject more unfair offers in a behavioural economic game (the ultimatum game). This study is the first to test this hypothesis.

Concepts: Game theory, Economics, Assessment, Psychometrics, Motivation, Dictator game, Reciprocity, Subgame perfect equilibrium


Social decision making has recently been evaluated in alcohol use disorder (AUD) using the ultimatum game (UG) task, suggesting a possible deficit in aversive emotion regulation elicited by the unfairness during this task. Despite the relevance to relapse of this possible faulty regulation, the brain correlates of the UG in AUD are unknown.

Concepts: Game theory, Psychology, Critical thinking, Cognition, Decision theory, Dictator game, Rulemaking, Subgame perfect equilibrium


In this research we examine the phenomenon of egocentric reciprocity, where individuals protect self-interest by adopting an eye-for-an-eye strategy in negatively imbalanced exchanges, and by taking advantage of overly generous treatment in positively imbalanced exchanges. We conducted two experiments using a modified ultimatum game examining attitudinal and behavioral responses to imbalanced exchanges. The experiments allowed us to explore the moderating role of relational closeness (i.e., whether the game partner was a friend or a stranger) and the mediating role of anger and indebtedness in these moderated relationships. Our results consistently demonstrate the phenomenon of egocentric reciprocity. Most importantly, this research reveals that friendship places a boundary on this egocentric tendency, and that the effects may partially be explained by anger experienced in response to exchange.

Concepts: Game theory, Sociology, Interpersonal relationship, Dictator game, Mediation, Friendship, Exchange, Subgame perfect equilibrium