| 1. |
- Alger, I., et al.
(författare)
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Strategic behavior of moralists and altruists
- 2017
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- Does altruism and morality lead to socially better outcomes in strategic interactions than selfishness? We shed some light on this complex and non-trivial issue by examining a few canonical strategic interactions played by egoists, altruists and moralists. By altruists, we mean people who do not only care about their own material payoffs but also about those to others, and, by a moralist, we mean someone who cares about own material payoff and also about what would be his or her material payoff if others were to act like himself or herself. It turns out that both altruism and morality may improve or worsen equilibrium outcomes, depending on the nature of the game. Not surprisingly, both altruism and morality improve the outcomes in standard public goods games. In infinitely repeated games, however, both altruism and morality may diminish the prospects of cooperation, and to different degrees. In coordination games, morality can eliminate socially inefficient equilibria while altruism cannot.
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| 2. |
- Andersson, Lina
(författare)
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Cooperation between emotional players
- 2020
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper uses the framework of stochastic games to propose a model of emotions in repeated interactions. An emotional player can be in either a friendly, a neutral, or a hostile state of mind. The player transitions between the states of mind as a response to observed actions taken by the other player. The state of mind determines the player’s psychological payoff which together with a material payoff constitutes the player’s utility. In the friendly (hostile) state of mind the player has a positive (negative) concern for other players’ material payoffs. This paper shows how emotions can both facilitate and obstruct cooperation in a repeated prisoners’ dilemma game. In finitely repeated games a player who cares only for their own material payoffs can have an incentive to manipulate an emotional player into the friendly state of mind. In infinitely repeated games with two emotional players less patience is required to sustain cooperation. However, emotions can also obstruct cooperation if they make the players unwilling to punish each other, or if the players become hostile when punished.
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| 3. |
- Andersson, Ola, et al.
(författare)
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Nudge the Lunch : A Field Experiment Testing Menu-Primacy Effects on Lunch Choices
- 2021
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Ingår i: Games. - : MDPI. - 2073-4336. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- By way of a field experiment conducted at a university cafeteria this paper finds that placing a vegetarian option instead of a meat option at the top of a menu decreases the share of meat dishes sold by 11%. This translates to a 6% decrease of daily emissions due to food sales. Using data on payment method, we find that the result is most likely driven by non-students responding to the nudge.
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| 4. |
- Andersson, Ola, et al.
(författare)
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Speech Is Silver, Silence Is Golden
- 2013
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 4:3, s. 497-507
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Tidskriftsartikel (refereegranskat)abstract
- This paper experimentally investigates free-riding behavior on communication cost in a coordination game and finds strong indications of such free-riding. Firstly,the subjects wait for others to send a message when communication is costly, which does not happen when communication is costless. Secondly, the proportion of games where no communication or one-way communication takes place is much higher whencommunication is costly compared to when it is free.
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| 5. |
- Asheim, G. B., et al.
(författare)
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Epistemically robust strategy subsets
- 2016
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- We define a concept of epistemic robustness in the context of an epistemic model of a finite normal-form game where a player type corresponds to a belief over the profiles of opponent strategies and types. A Cartesian product X of pure-strategy subsets is epistemically robust if there is a Cartesian product Y of player type subsets with X as the associated set of best reply profiles such that the set Yi contains all player types that believe with sufficient probability that the others are of types in Y-i and play best replies. This robustness concept provides epistemic foundations for set-valued generalizations of strict Nash equilibrium, applicable also to games without strict Nash equilibria. We relate our concept to closedness under rational behavior and thus to strategic stability and to the best reply property and thus to rationalizability.
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| 6. |
- Aurell, Alexander
(författare)
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Mean-Field Type Games between Two Players Driven by Backward Stochastic Differential Equations
- 2018
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, mean-field type games between two players with backward stochastic dynamics are defined and studied. They make up a class of non-zero-sum, non-cooperating, differential games where the players’ state dynamics solve backward stochastic differential equations (BSDE) that depend on the marginal distributions of player states. Players try to minimize their individual cost functionals, also depending on the marginal state distributions. Under some regularity conditions, we derive necessary and sufficient conditions for existence of Nash equilibria. Player behavior is illustrated by numerical examples, and is compared to a centrally planned solution where the social cost, the sum of playercosts, is minimized. The inefficiency of a Nash equilibrium, compared to socially optimal behavior, is quantified by the so-called price of anarchy. Numerical simulations of the price of anarchy indicate how the improvement in social cost achievable by a central planner depends on problem parameters.
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| 7. |
- Brännström, Åke, et al.
(författare)
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The Hitchhiker's guide to adaptive dynamics
- 2013
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 4:3, s. 304-328
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Tidskriftsartikel (refereegranskat)abstract
- Adaptive dynamics is a mathematical framework for studying evolution. It extends evolutionary game theory to account for more realistic ecological dynamics and it can incorporate both frequency- and density-dependent selection. This is a practical guide to adaptive dynamics that aims to illustrate how the methodology can be applied to the study of specific systems. The theory is presented in detail for a single, monomorphic, asexually reproducing population. We explain the necessary terminology to understand the basic arguments in models based on adaptive dynamics, including invasion fitness, the selection gradient, pairwise invasibility plots (PIP), evolutionarily singular strategies, and the canonical equation. The presentation is supported with a worked-out example of evolution of arrival times in migratory birds. We show how the adaptive dynamics methodology can be extended to study evolution in polymorphic populations using trait evolution plots (TEPs). We give an overview of literature that generalises adaptive dynamics techniques to other scenarios, such as sexual, diploid populations, and spatially-structured populations. We conclude by discussing how adaptive dynamics relates to evolutionary game theory and how adaptive-dynamics techniques can be used in speciation research.
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| 8. |
- Choutri, Salah eddine, et al.
(författare)
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A Stochastic Maximum Principle for Markov Chains of Mean-Field Type
- 2018
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- We derive sufficient and necessary optimality conditions in terms of a stochastic maximum principle (SMP) for controls associated with cost functionals of mean-field type, under dynamics driven by a class of Markov chains of mean-field type which are pure jump processes obtained as solutions of a well-posed martingale problem. As an illustration, we apply the result to generic examples of control problems as well as some applications.
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| 9. |
- Coder Gylling, Kira, 1988-, et al.
(författare)
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Effects of Relatedness on the Evolution of Cooperation in Nonlinear Public Goods Games
- 2018
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Ingår i: Games. - : MDPI. - 2073-4336. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Evolution of cooperation has traditionally been studied by assuming that individuals adopt either of two pure strategies, to cooperate or defect. Recent work has considered continuous cooperative investments, turning full cooperation and full defection into two opposing ends of a spectrum and sometimes allowing for the emergence of the traditionally-studied pure strategies through evolutionary diversification. These studies have typically assumed a well-mixed population in which individuals are encountered with equal probability. Here, we allow for the possibility of assortative interactions by assuming that, with specified probabilities, an individual interacts with one or more other individuals of the same strategy. A closely related assumption has previously been made in evolutionary game theory and has been interpreted in terms of relatedness. We systematically study the effect of relatedness and find, among other conclusions, that the scope for evolutionary branching is reduced by either higher average degree of, or higher uncertainty in, relatedness with interaction partners. We also determine how different types of non-linear dependencies of benefits and costs constrain the types of evolutionary outcomes that can occur. While our results overall corroborate the conclusions of earlier studies, i.e. higher relatedness promotes the evolution of cooperation, our investigation gives a comprehensive picture of how relatedness affects the evolution of cooperation with continuous investments.
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| 10. |
- Farjam, Mike, 1986-, et al.
(författare)
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Ignorance Is Bliss, But for Whom? The Persistent Effect of Good Will on Cooperation
- 2016
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Ingår i: Games. - : M D P I AG. - 2073-4336. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Who benefits from the ignorance of others? We address this question from the point of view of a policy maker who can induce some ignorance into a system of agents competing for resources. Evolutionary game theory shows that when unconditional cooperators or ignorant agents compete with defectors in two-strategy settings, unconditional cooperators get exploited and are rendered extinct. In contrast, conditional cooperators, by utilizing some kind of reciprocity, are able to survive and sustain cooperation when competing with defectors. We study how cooperation thrives in a three-strategy setting where there are unconditional cooperators, conditional cooperators and defectors. By means of simulation on various kinds of graphs, we show that conditional cooperators benefit from the existence of unconditional cooperators in the majority of cases. However, in worlds that make cooperation hard to evolve, defectors benef
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| 11. |
- Lindgren, Kristian, 1960, et al.
(författare)
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Evolutionary Exploration of the Finitely Repeated Prisoners' Dilemma -- The Effect of Out-of-Equilibrium Play
- 2013
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 4:1, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The finitely repeated Prisoners’ Dilemma is a good illustration of the discrepancy between the strategic behaviour suggested by a game-theoretic analysis and the behaviour often observed among human players, where cooperation is maintained through most of the game. A game-theoretic reasoning based on backward induction eliminates strategies step by step until defection from the first round is the only remaining choice, reflecting the Nash equilibrium of the game. We investigate the Nash equilibrium solution for two different sets of strategies in an evolutionary context, using replicator-mutation dynamics. The first set consists of conditional cooperators, up to a certain round, while the second set in addition to these contains two strategy types that react differently on the first round action: The ”Convincer” strategies insist with two rounds of initial cooperation, trying to establish more cooperative play in the game, while the ”Follower” strategies, although being first round defectors, have the capability to respond to an invite in the first round. For both of these strategy sets, iterated elimination of strategies shows that the only Nash equilibria are given by defection from the first round. We show that the evolutionary dynamics of the first set is always characterised by a stable fixed point, corresponding to the Nash equilibrium, if the mutation rate is sufficiently small (but still positive). The second strategy set is numerically investigated, and we find that there are regions of parameter space where fixed points become unstable and the dynamics exhibits cycles of different strategy compositions. The results indicate that, even in the limit of very small mutation rate, the replicator-mutation dynamics does not necessarily bring the system with Convincers and Followers to the fixed point corresponding to the Nash equilibrium of the game. We also perform a detailed analysis of how the evolutionary behaviour depends on payoffs, game length, and mutation rate.
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| 12. |
- Michaeli, Moti, et al.
(författare)
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Prescriptive Norms and Social Comparisons
- 2018
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Ingår i: Games. - : MDPI. - 2073-4336. ; 9:4, s. 97-97
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes the equilibrium strength of prescriptive norms to contribute to public goods. We consider three methods of establishing what an acceptable contribution to the public good is. Under the first method, the contribution of the bottom contributor is the reference point by which the comparison is being made; under the second, the median contribution is the reference point; and under the third the top contribution is the reference. The first method results in a unique equilibrium and the reference contribution is endogenously low. Each of the latter two methods allows for multiple equilibria differing in contributions made and thus in the strength of the norm to contribute. Comparing the methods we show that the median reference allows for the highest equilibrium contributions and welfare of all methods hence is the preferred method if, among the multiple equilibria, the best one can be selected. However, the bottom-reference is the maximin method, i.e., it provides safe minimal aggregate contribution and welfare that surpass the worst outcome in the other two methods.
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| 13. |
- Olsson, Ola, 1971
(författare)
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Climate Change and Market Collapse: A Model Applied to Darfur
- 2016
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 7(1):9, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- A recurring argument in the global debate is that climate deterioration is likely to make social conflicts over diminishing natural resources more common in the future. The exact mechanism behind such a development has so far not been successfully characterized in the literature. In this paper, we present a general model of a community populated by farmers and herders who can either divide up land in a market economy or in autarky. The key insight from our model is that decreasing resources can make trade between the two groups collapse, which in turn makes each group’s welfare independent of that of the other. Predictions from the model are then applied to the conflict in Darfur. Our analysis suggests that three decades of drought in the area can at least partially explain the observed disintegration of markets and the subsequent rise of social tensions.
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| 14. |
- Voorneveld, Mark, et al.
(författare)
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A Scent of Lemon: Seller Meets Buyer with a Noisy Quality Observation
- 2011
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Ingår i: Games. - : MDPI. - 2073-4336 .- 2073-4336. ; 2:1, s. 163-186
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Tidskriftsartikel (refereegranskat)abstract
- We consider a market for lemons in which the seller is a monopolistic price setter and the buyer receives a private noisy signal of the product's quality. We model this as a game and analyze perfect Bayesian equilibrium prices, trading probabilities and gains of trade. In particular, we vary the buyer's signal precision, from being completely uninformative, as in standard models of lemons markets, to being perfectly informative. We show that high quality units are sold with positive probability even in the limit of uninformative signals, and we identify some discontinuities in the equilibrium predictions at the boundaries of completely uninformative and completely informative signals, respectively.
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| 15. |
- Realpe-Gómez, J., et al.
(författare)
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Learning dynamics and norm psychology supports human cooperation in a large-scale prisoner’s dilemma on networks
- 2018
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Ingår i: Games. - : MDPI AG. - 2073-4336. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we explore the role of learning dynamics and social norms in human cooperation on networks. We study the model recently introduced in [Physical Review E, 97, 042321 (2018)] that integrates the well-studied Experience Weighted Attraction learning model with some features characterizing human norm psychology, namely the set of cognitive abilities humans have evolved to deal with social norms. We provide further evidence that this extended model—that we refer to as Experience Weighted Attraction with Norm Psychology—closely reproduces cooperative patterns of behavior observed in large-scale experiments with humans. In particular, we provide additional support for the finding that, when deciding to cooperate, humans balance between the choice that returns higher payoffs with the choice in agreement with social norms. In our experiment, agents play a prisoner’s dilemma game on various network structures: (i) a static lattice where agents have a fixed position; (ii) a regular random network where agents have a fixed position; and (iii) a dynamic lattice where agents are randomly re-positioned at each game iteration. Our results show that the network structure does not affect the dynamics of cooperation, which corroborates results of prior laboratory experiments. However, the network structure does seem to affect how individuals balance between their self-interested and normative choices.
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