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Angel Sanchez - One of the best experts on this subject based on the ideXlab platform.
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emotions and strategic behaviour the case of the Ultimatum Game
PLOS ONE, 2016Co-Authors: Ignacio Tamarit, Angel SanchezAbstract:Human behaviour in economic interactions has attracted an increasing amount of attention over the last decades. The economic assumption that people would behave focusing on their own material self-interest was proved incomplete, once the empirical evidence consistently showed that many other motives may influence such behaviour. Therefore, models that can incorporate rational decision process as well as other intervening factors are a key issue to both understand the observations from economic experiments and to apply the lessons learned from them. In this paper, we incorporate the influence of emotions to the utility function in an explicit manner, using the Ultimatum Game as a case study. Our model is amenable to analytical study, and is connected with the Circumplex model of emotions and with Kahneman’s two-system theory. The simplicity of the model allows to obtain predictions for the offers and acceptance thresholds. We study two specific examples, when the model parameters are distributed uniformly or normally, and show that in the latter case the results are already qualitatively correct. Although this work can be considered as a first approach, it includes what we believe are the main stylized facts, is able to qualitatively reproduce experimental results in a very simple manner, and can be straightforwardly extended to other Games.
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empathy emerges spontaneously in the Ultimatum Game small groups and networks
PLOS ONE, 2012Co-Authors: Jaime Iranzo, Angel Sanchez, L M Floria, Yamir MorenoAbstract:The Ultimatum Game, in which one subject proposes how to share a pot and the other has veto power on the proposal, in which case both lose everything, is a paradigmatic scenario to probe the degree of cooperation and altruism in human subjects. It has been shown that if individuals are empathic, i.e., they play the Game having in mind how their opponent will react by offering an amount that they themselves would accept, then non-rational large offers well above the smallest possible ones are evolutionarily selected. We here show that empathy itself may be selected and need not be exogenously imposed provided that interactions take place only with a fraction of the total population, and that the role of proposer or responder is randomly changed from round to round. These empathic agents, that displace agents with independent (uncorrelated) offers and proposals, behave far from what is expected rationally, offering and accepting sizable fractions of the amount to be shared. Specific values for the typical offer depend on the details of the interacion network and on the existence of hubs, but they are almost always significantly larger than zero, indicating that the mechanism at work here is quite general and could explain the emergence of empathy in very many different contexts.
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the spatial Ultimatum Game revisited
Journal of Theoretical Biology, 2011Co-Authors: Jaime Iranzo, Javier Roman, Angel SanchezAbstract:We revisit the issue of the emergence of fair behavior in the framework of the spatial Ultimatum Game, adding many important results and insights to the pioneering work by Page et al. [2000. The spatial Ultimatum Game. Proc. R. Soc. London B 267, 2177], who showed in a specific example that on a two-dimensional setup evolution may lead to strategies with some degree of fairness. Within this spatial framework, we carry out a thorough simulation study and show that the emergence of altruism is a very generic phenomenon whose details depend on the dynamics considered. A very frequent feature is the spontaneous emergence and fixation of quasiempathetic individuals, whose offers are very close to their acceptance thresholds. We present analytical arguments that allow an understanding of our results and give insights on the manner in which local effects in evolution may lead to such non-rational or apparently maladaptive behaviors.
Abigail Wozniak - One of the best experts on this subject based on the ideXlab platform.
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racial differences in inequality aversion evidence from real world respondents in the Ultimatum Game
Journal of Economic Behavior and Organization, 2012Co-Authors: John D Griffin, David W Nickerson, Abigail WozniakAbstract:Abstract The distinct historical and cultural experiences of American blacks and whites may influence whether members of these groups perceive a particular exchange as fair. We investigate racial differences in fairness standards using preferences for equal treatment in the Ultimatum Game. We focus on whether responders choose to accept a proposed division of a monetary amount or to block it. We use a sample of over 1600 blacks and whites drawn from the universe of registered voters in three states merged with information on neighborhood income and racial composition. We experimentally vary proposed divisions as well as the implied race of the proposer. We find that acceptance in both groups is strongly influenced by the level of inequity in a proposed division, but blacks are also influenced by the offer amount while whites are not. This is driven by the lowest income group in our sample, which represents the 10th percentile of the black income distribution. We are able to reject that blacks and whites in this group share a common, simple utility function. We also find that blacks are more sensitive to unfair proposals from other blacks.
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racial differences in inequality aversion evidence from real world respondents in the Ultimatum Game
Research Papers in Economics, 2011Co-Authors: John D Griffin, David W Nickerson, Abigail WozniakAbstract:The distinct historical and cultural experiences of American blacks and whites may influence whether members of those groups perceive a particular exchange as fair. We investigate racial differences in fairness standards using preferences for equal treatment in the Ultimatum Game, where responders choose to allow a proposed division of a monetary amount or to block it. Although previous research has studied group differences in the Ultimatum Game, no study has been able to examine these across races in America. We use a sample of over 1600 blacks and whites drawn from the universe of registered voters in three states and merged with information on neighborhood income and racial composition. We experimentally vary proposed divisions as well as the implied race of the Ultimatum Game proposer. We find no overall racial differences in acceptance rates or aversion to inequality. However, we uncover racial differences in Ultimatum Game behavior on other dimensions. Many of these are driven by the lowest income group in our sample, which represents the 10th percentile of the black income distribution. We also find that blacks are more sensitive to unfair proposals from other blacks.
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racial differences in inequality aversion evidence from real world respondents in the Ultimatum Game
Social Science Research Network, 2011Co-Authors: John D Griffin, David W Nickerson, Abigail WozniakAbstract:The distinct historical and cultural experiences of American blacks and whites may influence whether members of those groups perceive a particular exchange as fair. We investigate racial differences in fairness standards using preferences for equal treatment in the Ultimatum Game, where responders choose to allow a proposed division of a monetary amount or to block it. Although previous research has studied group differences in the Ultimatum Game, no study has been able to examine these across races in America. We use a sample of over 1600 blacks and whites drawn from the universe of registered voters in three states and merged with information on neighborhood income and racial composition. We experimentally vary proposed divisions as well as the implied race of the Ultimatum Game proposer. We find no overall racial differences in acceptance rates or aversion to unequal divisions. However, we uncover racial differences in the response to pecuniary returns conditional on inequality of the division. This is driven by the lowest income group in our sample, which represents the 10th percentile of the black income distribution. The racial differences are robust across gender and age groups. We also find that blacks are more sensitive to unfair proposals from other blacks.
Aldo Rustichini - One of the best experts on this subject based on the ideXlab platform.
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testosterone administration does not affect men s rejections of low Ultimatum Game offers or aggressive mood
Hormones and Behavior, 2017Co-Authors: Carlos Cueva, Edward R Roberts, Thomas J Spencer, Nisha Rani, Michelle Tempest, Philippe N Tobler, J Herbert, Aldo RustichiniAbstract:Correlative evidence suggests that testosterone promotes dominance and aggression. However, causal evidence is scarce and offers mixed results. To investigate this relationship, we administered testosterone for 48h to 41 healthy young adult men in a within-subjects, double-blind placebo-controlled balanced crossover design. Subjects played the role of responders in an Ultimatum Game, where rejecting a low offer is costly, but serves to destroy the proposer's profit. Such action can hence be interpreted as non-physical aggression in response to social provocation. In addition, subjects completed a self-assessed mood questionnaire. As expected, self-reported aggressiveness was a key predictor of Ultimatum Game rejections. However, while testosterone affected subjective ratings of feeling energetic and interested, our evidence strongly suggests that testosterone had no effect on Ultimatum Game rejections or on aggressive mood. Our findings illustrate the importance of using causal interventions to assess correlative evidence.
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neuroeconomics of 3 person Ultimatum Game with voting the case of responders
2009Co-Authors: Jarosoaw Grygolec, Giorgio Coricelli, Aldo RustichiniAbstract:We study responders’ behavior and corresponding brain activity in 3-person Ultimatum Game with voting in an fMRI experiment. In the Game a proposer decides the split of the pie between himself and 2 responders. If the proposed split gets majority support among 3 players it is implemented, otherwise each player gets nothing. The design has two advantages. First, it avoids priming to discriminate against one of players as in 3-person Ultimatum with a dummy of Guth, van Damme (1998). Second, it allows naturally for situations to arise in which a responder receives either less or more than one of players. The latter is unlike in the classical 2-person Ultimatum Game where proposers’ advantage, experimentally a sure thing, effectively prevents studying responders’ social preferences in the domain of advantageous inequality of a responder. In this paper we focus on low but positive offers to a responder inside MRI machine. The analysis reveals that the decision process on such offers can be separated into two stages. We observed increased activity in nucleus accumbens (positive reward) and amygdala (negative emotion) in the early stage. We interpret this as evidence of a decision conflict, which is detected by anterior cingulate cortex and resolved with help of bilateral insula and right dorso-lateral prefrontal cortex in the late stage of offer evaluation. Based on presented evidence we suggest that the involvement of negative emotions in rejections of low but positive offers is not due to their unfairness, but rather reflects negative reputational signal that the actual acceptance can send to others about the responder.
Long Wang - One of the best experts on this subject based on the ideXlab platform.
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evolution of fairness in the mixture of the Ultimatum Game and the dictator Game
Physica A-statistical Mechanics and Its Applications, 2019Co-Authors: Wei Chen, Long WangAbstract:Abstract The Ultimatum Game characterizes the scheme to split a sum of money between the proposer and the responder. Both players benefit from the successful allocation whenever the scheme presented by the proposer is endorsed by the responder, yet both receive nothing otherwise. Meanwhile, the responder in the Dictator Game has no choice but to accept what is offered by the proposer. As both Games may occur in some realistic situations, we study the population dynamics by considering the mixture of the Ultimatum Game and the Dictator Game. Mixture means a fraction of individuals play the Dictator Game with their partners while others play the Ultimatum Game. We introduce degree-related assignment rules to determine who shall play the Dictator Game in the heterogeneous populations. Our results show that the evolution of fairness can be promoted by assigning an appropriate fraction of hubs to be dictators, a novel finding deviating from the subGame perfect Nash equilibrium where proposers tend to leave next to nothing to their responders. Our work highlights the importance of network reciprocity in enhancing the evolution of fairness.
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random allocation of pies promotes the evolution of fairness in the Ultimatum Game
Scientific Reports, 2015Co-Authors: Xiaofeng Wang, Xiaojie Chen, Long WangAbstract:In the Ultimatum Game, two players are offered a chance to win a pie. The proposer suggests how to split the pie. The responder can either accept or reject the deal. If an agreement is not reached, neither player gets anything. Both Game theory and evolutionary Game theory predict the rational solution that the proposer offers the smallest possible share and the responder accepts it. Fairness thus requires additional mechanisms for natural selection to favor it. Studies to date assumed that individuals have competed for the fixed size of pies, in sharp contrast with real situations, where randomness is ubiquitous. Here we study the impact of random allocation of pies on the evolution of fairness in the Ultimatum Game. Interestingly, we find that the evolution of fairness can be promoted by the randomness associated with the size of pies, without the support of any additional evolutionary mechanisms.
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effects of partner choice and role assignation in the spatial Ultimatum Game
EPL, 2015Co-Authors: Zhihu Yang, Long WangAbstract:Hitherto, there has been an increasing interest in the Ultimatum Game, an elegant metaphor constituted for decoding the self-organization of fair behavior. Most previous studies have been done in the context of unbiased partner selection and symmetric role assignation. However, this is not always the case. To investigate the role of partner choice and role allocation on fairness, we develop a co-evolutionary Ultimatum Game in which agents can dynamically choose interacting neighbors as well as allocate Game roles based on the real-time feedback from interactions. By the Monte Carlo simulation, we find that the related biases always play a crucial role in transforming the evolution of fairness. More specifically, the fairness level can be strikingly promoted when agents often aspire for interactions with more successful players and frequently designate reputable ones as proposers in the Ultimatum Game. For other cases, however, fairness is often remarkably inhibited. Compared with weak selection, strong selection turns out to be more favorable to the evolution of fair behavior. Finally, with proper parameters we witness the spontaneous emergence of social fairness in a totally self-regarding population under the noisy condition.
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adaptive role switching promotes fairness in networked Ultimatum Game
Scientific Reports, 2013Co-Authors: Yanling Zhang, Long WangAbstract:In recent years, mechanisms favoring fair split in the Ultimatum Game have attracted growing interests because of its practical implications for international bargains. In this Game, two players are randomly assigned two different roles respectively to split an offer: the proposer suggests how to split and the responder decides whether or not to accept it. Only when both agree is the offer successfully split; otherwise both get nothing. It is of importance and interest to break the symmetry in role assignment especially when the Game is repeatedly played in a heterogeneous population. Here we consider an adaptive role assignment: whenever the split fails, the two players switch their roles probabilistically. The results show that this simple feedback mechanism proves much more effective at promoting fairness than other alternatives (where, for example, the role assignment is based on the number of neighbors).
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the coevolutionary Ultimatum Game
EPL, 2011Co-Authors: Jia Gao, Long WangAbstract:We develop a minimal model to explore coevolutionary dynamics on spatial Ultimatum Game. Individuals are endowed with the capacity to adjust both their strategy and their social ties. Under strategy dynamics, individuals preferentially imitate the strategy of more successful neighbors. Meanwhile, the egoists, whose offers do not satisfy the partners, run the risk of being dismissed. We find that individuals make fairer offers when they are allowed to switch adverse partnerships. Remarkably, the promotion of fairness by partner rewiring is offset in a certain extent by the emergence of isolated individuals. We also investigate the influence of the average degree on the evolution of fairness under our coevolutionary rules. It is found that a smaller average degree leads to a fairer society under the condition of low partner rewiring frequency. However, if partner rewiring frequency is high, a dense network where isolated individuals are not apt to emerge, is favorable for the establishment of fairness.
Stephen Paul - One of the best experts on this subject based on the ideXlab platform.
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Ultimatum Game bargaining in a partially directed search market
Journal of Economic Behavior and Organization, 2018Co-Authors: Andrew Kloosterman, Stephen PaulAbstract:Abstract We investigate a partially directed search and bargaining market with a laboratory experiment. First, sellers post intervals of possible surplus splits (i.e. the payoffs that would result from posting possible prices) that direct buyers to approach them. Second, after matching occurs, final surpluses are determined by Ultimatum Game bargaining. We investigate the interaction between bargaining and competition in the preliminary search stage, with a focus on how preferences for fair bargaining outcomes affect search. The main results confirm that behavior in the Ultimatum Game is consistent with preferences for fair outcomes, and the main effect on search is to drive up the posted buyer surplus lower bounds above the competitive equilibrium towards more equal surplus splits. Our main treatment variable is the number of buyers in the market, and when the number of buyers is increased, lower bounds and Ultimatum offers to buyers decrease. This is consistent with fairness perceptions being influenced by competition.
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Ultimatum Game bargaining in a partially directed search market
Social Science Research Network, 2018Co-Authors: Andrew Kloosterman, Stephen PaulAbstract:We investigate a partially directed search market where buyers search for sellers and then final prices are determined by Ultimatum Game bargaining. In the search stage of this Game, sellers post intervals of possible surplus splits to attract buyers and then buyers approach one seller from whom they attempt to purchase. Our main goal is to investigate the interaction between bargaining and competition in the preliminary search stage. The main results confirm that behavior in the Ultimatum Game is consistent with past findings (i.e., fairness matters), and the main effect on search is to drive up the posted lower bounds for buyer surplus above the competitive equilibrium (towards more equal splits). Our main treatment variable is the number of buyers in the market, and when the number of buyers is increased, lower bounds and Ultimatum offers to buyers decrease. This is consistent with fairness perceptions being influenced by competition.
