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Prisoner, dilemma

Yutaka Horita, Masanori Takezawa, Keigo Inukai, Toshimasa Kita, Naoki Masuda
In social dilemma games, human participants often show conditional cooperation (CC) behavior or its variant called moody conditional cooperation (MCC), with which they basically tend to cooperate when many other peers have previously cooperated. Recent computational studies showed that CC and MCC behavioral patterns could be explained by reinforcement learning. In the present study, we use a repeated multiplayer prisoner's dilemma game and the repeated public goods game played by human participants to examine whether MCC is observed across different types of game and the possibility that reinforcement learning explains observed behavior...
January 10, 2017: Scientific Reports
Vlastimil Křivan, Ross Cressman
Two most influential models of evolutionary game theory are the Hawk-Dove and Prisoner's dilemma models. The Hawk-Dove model explains evolution of aggressiveness, predicting individuals should be aggressive when the cost of fighting is lower than its benefit. As the cost of aggressiveness increases and outweighs benefits, aggressiveness in the population should decrease. Similarly, the Prisoner's dilemma models evolution of cooperation. It predicts that individuals should never cooperate despite cooperation leading to a higher collective fitness than defection...
January 6, 2017: Journal of Theoretical Biology
Ilona Reding, Michael Kelley, Jonathan T Rowell, Jan Rychtář
Population distributions depend upon the aggregate behavioural responses of individuals to a range of environmental factors. We extend a model of ideally motivated populations to describe the local and regional consequences of interactions between three populations distinguished by their levels of cooperation and exploitation. Inspired by the classic prisoner's dilemma game, stereotypical fitness functions describe a baseline non-cooperative population whose per capita fitness decreases with density, obligate co-operators who initially benefit from the presence of conspecifics, and kleptoparasites who require heterospecifics to extract resources from the environment...
November 2016: Royal Society Open Science
Ozgur Aydogmus, Wen Zhou, Yun Kang
Nonlocal interactions such as spatial interaction are ubiquitous in nature and may alter the equilibrium in evolutionary dynamics. Models including nonlocal spatial interactions can provide a further understanding on the preservation and emergence of cooperation in evolutionary dynamics. In this paper, we consider a variety of two-strategy evolutionary spatial games with nonlocal interactions based on an integro-differential replicator equation. By defining the invasion speed and minimal traveling wave speed for the derived model, we study the effects of the payoffs, the selection pressure and the spatial parameter on the preservation of cooperation...
December 13, 2016: Mathematical Biosciences
József Garay, Villő Csiszár, Tamás F Móri
Game theory focuses on payoffs and typically ignores time constraints that play an important role in evolutionary processes where the repetition of games can depend on the strategies, too. We introduce a matrix game under time constraints, where each pairwise interaction has two consequences: both players receive a payoff and they cannot play the next game for a specified time duration. Thus our model is defined by two matrices: a payoff matrix and an average time duration matrix. Maynard Smith's concept of evolutionary stability is extended to this class of games...
December 1, 2016: Journal of Theoretical Biology
Juan Wang, Wenwen Lu, Lina Liu, Li Li, Chengyi Xia
In the field of evolutionary game theory, network reciprocity has become an important means to promote the level of promotion within the population system. Recently, the interdependency provides a novel perspective to understand the widespread cooperation behavior in many real-world systems. In previous works, interdependency is often built from the direct or indirect connections between two networks through the one-to-one mapping mode. However, under many realistic scenarios, players may need much more information from many neighboring agents so as to make a more rational decision...
2016: PloS One
Felix Henninger, Pascal J Kieslich, Benjamin E Hilbig
We introduce a novel platform for interactive studies, that is, any form of study in which participants' experiences depend not only on their own responses, but also on those of other participants who complete the same study in parallel, for example a prisoner's dilemma or an ultimatum game. The software thus especially serves the rapidly growing field of strategic interaction research within psychology and behavioral economics. In contrast to all available software packages, our platform does not handle stimulus display and response collection itself...
November 11, 2016: Behavior Research Methods
Laura Mieth, Raoul Bell, Axel Buchner
The present study serves to test how positive and negative appearance-based expectations affect cooperation and punishment. Participants played a prisoner's dilemma game with partners who either cooperated or defected. Then they were given a costly punishment option: They could spend money to decrease the payoffs of their partners. Aggregated over trials, participants spent more money for punishing the defection of likable-looking and smiling partners compared to punishing the defection of unlikable-looking and nonsmiling partners, but only because participants were more likely to cooperate with likable-looking and smiling partners, which provided the participants with more opportunities for moralistic punishment...
September 2016: Experimental Psychology
Riccardo Pansini, Lei Shi, Rui-Wu Wang
Cooperation theories assume that interacting individuals can change their strategies under different expected payoffs, depending on their social status or social situations. When looking at sex differences in cooperation, the existing studies have found that the genders cooperate at similar frequencies. However, the majority of the data originate within Western human societies. In this paper, we explore whether there are gender differences in cooperation in China. An Iterated Prisoner's Dilemma game with a punishment option was used to gather data about Southwest Chinese subjects in a culture in which men have a hierarchical advantage over women...
2016: PloS One
Kristen M Sorgi, Mascha van 't Wout
This study evaluated the influence of self-reported levels of depression on interpersonal strategic decision making when interacting with partners who differed in their predetermined tendency to cooperate in three separate computerized iterated Prisoner's Dilemma Games (iPDGs). Across 29 participants, cooperation was lowest when interacting with a predominantly defecting partner and highest when interacting with a predominantly cooperating partner. Greater depression severity was related to steadier and continued cooperation over trials with the cooperating partner, seeming to reflect a prosocial response tendency when interacting with this partner...
December 30, 2016: Psychiatry Research
Oliver P Hauser, Achim Hendriks, David G Rand, Martin A Nowak
Preserving global public goods, such as the planet's ecosystem, depends on large-scale cooperation, which is difficult to achieve because the standard reciprocity mechanisms weaken in large groups. Here we demonstrate a method by which reciprocity can maintain cooperation in a large-scale public goods game (PGG). In a first experiment, participants in groups of on average 39 people play one round of a Prisoner's Dilemma (PD) with their two nearest neighbours on a cyclic network after each PGG round. We observe that people engage in "local-to-global" reciprocity, leveraging local interactions to enforce global cooperation: Participants reduce PD cooperation with neighbours who contribute little in the PGG...
November 3, 2016: Scientific Reports
Nur Altınörs, Mehmet Haberal
OBJECTIVES: The aim of this study was to review and discuss the great variety of ethical issues related to organ donation, organ procurement, transplant activities, and new ethical problems created as a result of technologic and scientific developments. MATERIALS AND METHODS: An extensive literature survey was made, and expert opinions were obtained. RESULTS: The gap between demand and supply of organs for transplant has yielded to organ trafficking, organ tourism, and commercialism...
2016: Experimental and Clinical Transplantation
Bo-Yu Zhang, Song-Jia Fan, Cong Li, Xiu-Deng Zheng, Jian-Zhang Bao, Ross Cressman, Yi Tao
Cooperation coexisting with defection is a common phenomenon in nature and human society. Previous studies for promoting cooperation based on kin selection, direct and indirect reciprocity, graph selection and group selection have provided conditions that cooperators outcompete defectors. However, a simple mechanism of the long-term stable coexistence of cooperation and defection is still lacking. To reveal the effect of direct reciprocity on the coexistence of cooperation and defection, we conducted a simple experiment based on the Prisoner's Dilemma (PD) game, where the basic idea behind our experiment is that all players in a PD game should prefer a cooperator as an opponent...
October 24, 2016: Scientific Reports
Surajeet Chakravarty, Miguel A Fonseca, Sudeep Ghosh, Sugata Marjit
We examine the impact of religious identity and village-level religious fragmentation on behavior in Tullock contests. We report on a series of two-player Tullock contest experiments conducted on a sample of 516 Hindu and Muslim participants in rural West Bengal, India. Our treatments are the identity of the two players and the degree of religious fragmentation in the village where subjects reside. Our main finding is that the effect of social identity is small and inconsistent across the two religious groups in our study...
2016: PloS One
María Pereda
In this work, we aim to contribute to the understanding of human prosocial behavior by studying the influence that a particular form of social pressure, "being watched," has on the evolution of cooperative behavior. We study how cooperation emerges in multiplex complex topologies by analyzing a particular bidirectionally coupled dynamics on top of a two-layer multiplex network (duplex). The coupled dynamics appears between the prisoner's dilemma game in a network and a threshold cascade model in the other. The threshold model is intended to abstract the behavior of a network of vigilant nodes that impose the pressure of being observed altering hence the temptation to defect of the dilemma...
September 2016: Physical Review. E
Jianlei Zhang, Franz J Weissing, Ming Cao
A commonly used assumption in evolutionary game theory is that natural selection acts on individuals in the same time scale; e.g., players use the same frequency to update their strategies. Variation in learning rates within populations suggests that evolutionary game theory may not necessarily be restricted to uniform time scales associated with the game interaction and strategy adaption evolution. In this study, we remove this restricting assumption by dividing the population into fast and slow groups according to the players' strategy updating frequencies and investigate how different strategy compositions of one group influence the evolutionary outcome of the other's fixation probabilities of strategies within its own group...
September 2016: Physical Review. E
Maika Rawolle, Oliver C Schultheiss, Alexandra Strasser, Hugo M Kehr
OBJECTIVE: Visionary images are identity-relevant, picture-like mental representations of a desirable and attainable future appearing regularly in a person's stream of thought. Prior research indicates that both mental and real images provide access to implicit motives. We therefore proposed that visionary images motivate people by arousing their implicit motives and tested this hypothesis in two experimental studies. METHOD: We used guided visualizations to administer motive-domain-specific visionary images (Study 1: achievement and neutral, Mage  = 24...
October 7, 2016: Journal of Personality
Shun Kurokawa
Cooperation is a mysterious phenomenon which is observed in this world. The potential explanation is a repeated interaction. Cooperation is established if individuals meet the same opponent repeatedly and cooperate conditionally. Previous studies have analyzed the following four as characters of conditional cooperators mainly. (i) niceness (i.e., when a conditional cooperator meets an opponent in the first place, he (she) cooperates or defects), (ii) optimism (when a conditional cooperator meets an opponent in the past, but he (she) did not get access to information about the opponent's behavior in the previous round, he (she) cooperates or defects), (iii) generosity (even when a conditional cooperator knows that an opponent defected in the previous round, he (she) cooperates or defects) and (iv) retaliation (a conditional cooperator cooperates with a cooperator with a higher probability than with a defector)...
December 2016: Mathematical Biosciences
Su Do Yi, Seung Ki Baek, Jung-Kyoo Choi
One of the most important questions in game theory concerns how mutual cooperation can be achieved and maintained in a social dilemma. In Axelrod's tournaments of the iterated prisoner's dilemma, Tit-for-Tat (TFT) demonstrated the role of reciprocity in the emergence of cooperation. However, the stability of TFT does not hold in the presence of implementation error, and a TFT population is prone to neutral drift to unconditional cooperation, which eventually invites defectors. We argue that a combination of TFT and anti-TFT (ATFT) overcomes these difficulties in a noisy environment, provided that ATFT is defined as choosing the opposite to the opponent's last move...
January 7, 2017: Journal of Theoretical Biology
Emilia Bea
This article approaches the testimony of the Alsatian psychiatrist Dr Adélaïde Hautval on the pseudo-medicine that was practiced in the Medical experimentation Block 10 of Auschwitz Birkenau, and on her refusal to take part in this crime against humanity. By reading her deportation diary and the acts of a peculiar judgment in Auschwitz that was celebrated in London in 1964, we are confronted with the ethical and professional dilemmas that doctors, who were themselves prisoners, had to face in this situation, and that incited them to resist inhumanity by acts, to disobey their superiors, and to be solidary with the victims...
May 2016: Cuadernos de Bioética: Revista Oficial de la Asociación Española de Bioética y Ética Médica
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