Página 1 dos resultados de 85 itens digitais encontrados em 0.068 segundos

‣ Does group size matter? Cheating and cooperation in Brazilian school children

ALENCAR, Anuska Irene; SIQUEIRA, Jose de Oliveira; YAMAMOTO, Maria Emilia
Fonte: ELSEVIER SCIENCE INC Publicador: ELSEVIER SCIENCE INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.253774%
Cooperation between individuals is an important requisite for the maintenance of social relationships. The purpose of this study was to investigate cooperation in children in the school environment, where individuals could cooperate or not with their classmates in a public goods game. We investigated which of the following variables influenced cooperation in children: sex, group size, and information on the number of sessions. Group size was the only factor to significantly affect cooperation, with small-group children cooperating significantly more than those in large groups. Both sex and information had no effect on cooperation. We suggest that these results reflect the fact that, in small groups, individuals were more efficient in controlling and retaliating theirs peers than in large groups. (C) 2008 Elsevier Inc. All rights reserved.

‣ Economics and social psychology on public goods: experiments and explorations

Castro Caldas, J. M.; Rodrigues, J.; Carvalho, L. F.
Fonte: Dinâmia Publicador: Dinâmia
Tipo: Trabalho em Andamento
Publicado em //2003 Português
Relevância na Pesquisa
68.7277%
Economics and social psychology come from different traditions in social science, and in the past they seldom met. Their territories seemed to be well delimited. The former discipline’s mainstream focused on market mediated interactions, making sense of an asocial concept of action by referring it to “the ordinary business of life” (Marshall, 1920, I.II.1) where agent’s choices supposedly are independent from those of other parties in the transactions (Sugden, 2002); on the other hand, the second discipline descends from the more romantic view of man as a social being, and was stimulated by questions on why and how the immersion of individuals in the multitude, or the simple presence of others, appeared to transform behaviour. Lately, however, economics has started moving in a direction that reduces this gap. In a double but interrelated move, economics is adopting experimental methods familiar to those of social psychology, and is becoming more concerned with the relevance of rational choice in contexts where there is clear inter-individual dependence, raising questions to which social psychologists have already devoted considerable time and effort. As a part of this movement, social dilemmas, that is, “situations in which (a) individual group members can obtain higher outcomes (at least under some circumstances) if they pursue their individual interest while (b) the group obtains higher incomes if all group members further the group interest” (Dijk and Wilke...

‣ Stabilizing the Earth’s climate is not a losing game: Supporting evidence from public goods experiments

Milinski, Manfred; Semmann, Dirk; Krambeck, Hans-Jürgen; Marotzke, Jochem
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.3455%
Maintaining the Earth’s climate within habitable boundaries is probably the greatest “public goods game” played by humans. However, with >6 billion “players” taking part, the game seems to rule out individual altruistic behavior. Thus, climate protection is a problem of sustaining a public resource that everybody is free to overuse, a “tragedy of the commons” problem that emerges in many social dilemmas. We perform a previously undescribed type of public goods experiment with human subjects contributing to a public pool. In contrast to the standard protocol, here the common pool is not divided among the participants; instead, it is promised that the pool will be invested to encourage people to reduce their fossil fuel use. Our extensive experiments demonstrate that players can behave altruistically to maintain the Earth’s climate given the right set of circumstances. We find a nonzero basic level of altruistic behavior, which is enhanced if the players are provided with expert information describing the state of knowledge in climate research. Furthermore, personal investments in climate protection increase substantially if players can invest publicly, thus gaining social reputation. This increase occurs because subjects reward other subjects’ contributions to sustaining the climate...

‣ A general model of the public goods dilemma

Frank, Steven A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.74921%
An individually costly act that benefits all group members is a public good. Natural selection favors individual contribution to public goods only when some benefit to the individual offsets the cost of contribution. Problems of sex ratio, parasite virulence, microbial metabolism, punishment of noncooperators, and nearly all aspects of sociality have been analyzed as public goods shaped by kin and group selection. Here, I develop two general aspects of the public goods problem that have received relatively little attention. First, variation in individual resources favors selfish individuals to vary their allocation to public goods. Those individuals better endowed contribute their excess resources to public benefit, whereas those individuals with fewer resources contribute less to the public good. Thus, purely selfish behavior causes individuals to stratify into upper classes that contribute greatly to public benefit and social cohesion and to lower classes that contribute little to the public good. Second, if group success absolutely requires production of the public good, then the pressure favoring production is relatively high. By contrast, if group success depends weakly on the public good, then the pressure favoring production is relatively weak. Stated in this way...

‣ Public goods dilemma in asexual ant societies

Dobata, Shigeto; Tsuji, Kazuki
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
68.584165%
This study reports experimental evidence for the “public goods dilemma” between cooperators and cheaters in an asexual ant society, in which cheating is always more rewarding for individuals but cooperation at the cost of individual fitness leads to better performance of groups. Although this dilemma provides the basic principle of social evolution, its experimental demonstration with underlying genetics and fitness evaluation for both cooperators and cheaters still lacks in societies other than microbial ones. By showing the striking evolutionary convergence between microbial societies and insect societies in fitness consequences and in phenotypic plasticity of cooperators against cheaters, our result suggests that a wide range of scales of cooperative systems could be understood in a unified manner.

‣ Solutions to the public goods dilemma in bacterial biofilms

Drescher, Knut; Nadell, Carey D.; Stone, Howard A.; Wingreen, Ned S.; Bassler, Bonnie L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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Bacteria frequently live in densely populated surface-bound communities, termed biofilms [1-4]. Biofilm-dwelling cells rely on secretion of extracellular substances to construct their communities and to capture nutrients from the environment [5]. Some secreted factors behave as cooperative public goods: they can be exploited by non-producing cells [6-11]. The means by which public-good-producing bacteria avert exploitation in biofilm environments are largely unknown. Using experiments with Vibrio cholerae, which secretes extracellular enzymes to digest its primary food source, the solid polymer chitin, we show that the public goods dilemma may be solved by two very different mechanisms: cells can produce thick biofilms that confine the goods to producers, or fluid flow can remove soluble products of chitin digestion, denying access to non-producers. Both processes are unified by limiting the distance over which enzyme-secreting cells provide benefits to neighbors, resulting in preferential benefit to nearby clonemates and allowing kin selection to favor public good production. Our results demonstrate new mechanisms by which the physical conditions of natural habitats can interact with bacterial physiology to promote the evolution of cooperation.

‣ Preschoolers are sensitive to free riding in a public goods game

Vogelsang, Martina; Jensen, Keith; Kirschner, Sebastian; Tennie, Claudio; Tomasello, Michael
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 15/07/2014 Português
Relevância na Pesquisa
48.068213%
Despite the benefits of cooperation, selfish individuals often produce outcomes where everyone is worse off. This “tragedy of the commons” has been demonstrated experimentally in adults with the public goods game. Contributions to a public good decline over time due to free-riders who keep their endowments. Little is known about how children behave when confronted with this social dilemma. Forty-eight preschoolers were tested using a novel non-verbal procedure and simplified choices more appropriate to their age than standard economic approaches. The rate of cooperation was initially very low and rose in the second round for the girls only. Children were affected by their previous outcome, as they free rode more after experiencing a lower outcome compared to the other group members.

‣ Inducing a self-fulfilling prophecy in public goods games

Bra??as-Garza, Pablo; Fat??s, Enrique; Guill??n, Pablo
Fonte: Universidad de Granada. Departamento de Teor??a e Historia Econ??mica Publicador: Universidad de Granada. Departamento de Teor??a e Historia Econ??mica
Tipo: Relatório
Português
Relevância na Pesquisa
68.308457%
This study explores how a self-fulfilling prophecy can solve a social dilemma. We ran two experimental treatments, baseline and automata. Both consisted of a finitely repeated public goods game with a surprise restart. In the automata treatment it was announced that there might be automata playing a grim trigger strategy. This announcement became a self-fulfilling prophecy. That is, most participants actually followed a grim trigger strategy in the automata treatment resulting on an increase on the average contributions to the public good relative to the baseline treatment. Moreover, four out of nine groups managed to fully cooperate almost until the last period. Furthermore, after the surprise restart, when the automata threat is less credible, subjects??? behavior was very close to that in the original game.

‣ Social experiments in the mesoscale: humans playing a spatial prisioner's dilemma

Grujić, Jelena; Fosco, Constanza; Araujo, Lourdes; Cuesta, José A.; Sánchez, Angel
Fonte: Public Library of Science (PLoS) Publicador: Public Library of Science (PLoS)
Tipo: info:eu-repo/semantics/publishedVersion; info:eu-repo/semantics/article Formato: application/pdf
Publicado em /11/2010 Português
Relevância na Pesquisa
48.67302%
Background: The evolutionary origin of cooperation among unrelated individuals remains a key unsolved issue across several disciplines. Prominent among the several mechanisms proposed to explain how cooperation can emerge is the existence of a population structure that determines the interactions among individuals. Many models have explored analytically and by simulation the effects of such a structure, particularly in the framework of the Prisoner’s Dilemma, but the results of these models largely depend on details such as the type of spatial structure or the evolutionary dynamics. Therefore, experimental work suitably designed to address this question is needed to probe these issues. Methods and Findings: We have designed an experiment to test the emergence of cooperation when humans play Prisoner’s Dilemma on a network whose size is comparable to that of simulations. We find that the cooperation level declines to an asymptotic state with low but nonzero cooperation. Regarding players’ behavior, we observe that the population is heterogeneous, consisting of a high percentage of defectors, a smaller one of cooperators, and a large group that shares features of the conditional cooperators of public goods games. We propose an agent-based model based on the coexistence of these different strategies that is in good agreement with all the experimental observations. Conclusions: In our large experimental setup...

‣ The tragedy of the commons, the public goods dilemma, and the meaning of rivalry and excludability in evolutionary biology

Dionisio, F.; Gordo, I.
Fonte: Evolutionary Ecology Publicador: Evolutionary Ecology
Tipo: Artigo de Revista Científica
Publicado em //2006 Português
Relevância na Pesquisa
99.67829%
Problem: In the study of conflicts, both economists and evolutionary biologists use the concepts ‘tragedy of the commons’ and ‘public goods dilemma’. What is the relationship between the economist and evolutionist views of these concepts? Model features: The economics literature defines the tragedy of the commons and the public goods dilemma in terms of rivalry and excludability of the good. In contrast, evolutionists define these conflicts based on fitness functions with two components: individual and group components of fitness. Mathematical method: Evolutionary game theory and the calculation of evolutionarily stable strategy trait values by standard optimization techniques and by replacing slopes of group phenotype on individual genotype by coefficients of relatedness. Conclusion: There is a direct relationship between rivalry and the individual component of fitness and between excludability and the group component of fitness. Moreover, although the prisoner’s dilemma constitutes a suitable metaphor to analyse both the public goods dilemma and the tragedy of the commons, it gives the false idea that the two conflicts are symmetric since they refer to situations in which individuals consume a common resource – tragedy of the commons – or contribute to a collective action or common good – public goods dilemma. However...

‣ Evolutionary Stability in the Asymmetric Volunteer's Dilemma

He, Jun-Zhou; Wang, Rui-Wu; Li, Yao-Tang
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 11/08/2014 Português
Relevância na Pesquisa
48.81794%
It is often assumed that in public goods games, contributors are either strong or weak players and each individual has an equal probability of exhibiting cooperation. It is difficult to explain why the public good is produced by strong individuals in some cooperation systems, and by weak individuals in others. Viewing the asymmetric volunteer's dilemma game as an evolutionary game, we find that whether the strong or the weak players produce the public good depends on the initial condition (i.e., phenotype or initial strategy of individuals). These different evolutionarily stable strategies (ESS) associated with different initial conditions, can be interpreted as the production modes of public goods of different cooperation systems. A further analysis revealed that the strong player adopts a pure strategy but mixed strategies for the weak players to produce the public good, and that the probability of volunteering by weak players decreases with increasing group size or decreasing cost-benefit ratio. Our model shows that the defection probability of a “strong” player is greater than the “weak” players in the model of Diekmann (1993). This contradicts Selten's (1980) model that public goods can only be produced by a strong player...

‣ Evolutionary Dynamics of Strategic Behavior in a Collective-Risk Dilemma

Abou Chakra, Maria; Traulsen, Arne
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.35784%
A collective-risk social dilemma arises when a group must cooperate to reach a common target in order to avoid the risk of collective loss while each individual is tempted to free-ride on the contributions of others. In contrast to the prisoners' dilemma or public goods games, the collective-risk dilemma encompasses the risk that all individuals lose everything. These characteristics have potential relevance for dangerous climate change and other risky social dilemmas. Cooperation is costly to the individual and it only benefits all individuals if the common target is reached. An individual thus invests without guarantee that the investment is worthwhile for anyone. If there are several subsequent stages of investment, it is not clear when individuals should contribute. For example, they could invest early, thereby signaling their willingness to cooperate in the future, constantly invest their fair share, or wait and compensate missing contributions. To investigate the strategic behavior in such situations, we have simulated the evolutionary dynamics of such collective-risk dilemmas in a finite population. Contributions depend individually on the stage of the game and on the sum of contributions made so far. Every individual takes part in many games and successful behaviors spread in the population. It turns out that constant contributors...

‣ Evolutionary games and population dynamics: maintenance of cooperation in public goods games

Hauert, Christoph; Holmes, Miranda; Doebeli, Michael
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.819556%
The emergence and abundance of cooperation in nature poses a tenacious and challenging puzzle to evolutionary biology. Cooperative behaviour seems to contradict Darwinian evolution because altruistic individuals increase the fitness of other members of the population at a cost to themselves. Thus, in the absence of supporting mechanisms, cooperation should decrease and vanish, as predicted by classical models for cooperation in evolutionary game theory, such as the Prisoner's Dilemma and public goods games. Traditional approaches to studying the problem of cooperation assume constant population sizes and thus neglect the ecology of the interacting individuals. Here, we incorporate ecological dynamics into evolutionary games and reveal a new mechanism for maintaining cooperation. In public goods games, cooperation can gain a foothold if the population density depends on the average population payoff. Decreasing population densities, due to defection leading to small payoffs, results in smaller interaction group sizes in which cooperation can be favoured. This feedback between ecological dynamics and game dynamics can generate stable coexistence of cooperators and defectors in public goods games. However, this mechanism fails for pairwise Prisoner's Dilemma interactions and the population is driven to extinction. Our model represents natural extension of replicator dynamics to populations of varying densities.

‣ The Increased Risk of Joint Venture Promotes Social Cooperation

Wu, Te; Fu, Feng; Zhang, Yanling; Wang, Long
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/06/2013 Português
Relevância na Pesquisa
48.5225%
The joint venture of many members is common both in animal world and human society. In these public enterprizes, highly cooperative groups are more likely to while low cooperative groups are still possible but not probable to succeed. Existent literature mostly focuses on the traditional public goods game, in which cooperators create public wealth unconditionally and benefit all group members unbiasedly. We here institute a model addressing this public goods dilemma with incorporating the public resource foraging failure risk. Risk-averse individuals tend to lead a autarkic life, while risk-preferential ones tend to participate in the risky public goods game. For participants, group's success relies on its cooperativeness, with increasing contribution leading to increasing success likelihood. We introduce a function with one tunable parameter to describe the risk removal pattern and study in detail three representative classes. Analytical results show that the widely replicated population dynamics of cyclical dominance of loner, cooperator and defector disappear, while most of the time loners act as savors while eventually they also disappear. Depending on the way that group's success relies on its cooperativeness, either cooperators pervade the entire population or they coexist with defectors. Even in the later case...

‣ Dilemma of Dilemmas: How Collective and Individual Perspectives Can Clarify the Size Dilemma in Voluntary Linear Public Goods Dilemmas

Shank, Daniel B.; Kashima, Yoshihisa; Saber, Saam; Gale, Thomas; Kirley, Michael
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 23/03/2015 Português
Relevância na Pesquisa
69.566235%
Empirical findings on public goods dilemmas indicate an unresolved dilemma: that increasing size—the number of people in the dilemma—sometimes increases, decreases, or does not influence cooperation. We clarify this dilemma by first classifying public goods dilemma properties that specify individual outcomes as individual properties (e.g., Marginal Per Capita Return) and group outcomes as group properties (e.g., public good multiplier), mathematically showing how only one set of properties can remain constant as the dilemma size increases. Underpinning decision-making regarding individual and group properties, we propose that individuals are motivated by both individual and group preferences based on a theory of collective rationality. We use Van Lange's integrated model of social value orientations to operationalize these preferences as an amalgamation of outcomes for self, outcomes for others, and equality of outcomes. Based on this model, we then predict how the public good's benefit and size, combined with controlling individual versus group properties, produce different levels of cooperation in public goods dilemmas. A two (low vs. high benefit) by three (2-person baseline vs. 5-person holding constant individual properties vs. 5-person holding constant group properties) factorial experiment (group n = 99; participant n = 390) confirms our hypotheses. The results indicate that when holding constant group properties...

‣ How insurance affects altruistic provision in threshold public goods games

Zhang, Jianlei; Zhang, Chunyan; Cao, Ming
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 13/03/2015 Português
Relevância na Pesquisa
48.53705%
The occurrence and maintenance of cooperative behaviors in public goods systems have attracted great research attention across multiple disciplines. A threshold public goods game requires a minimum amount of contributions to be collected from a group of individuals for provision to occur. Here we extend the common binary-strategy combination of cooperation and defection by adding a third strategy, called insured cooperation, which corresponds to buying an insurance covering the potential loss resulted from the unsuccessful public goods game. Particularly, only the contributing agents can opt to be insured, which is an effort decreasing the amount of the potential loss occurring. Theoretical computations suggest that when agents face the potential aggregate risk in threshold public goods games, more contributions occur with increasing compensation from insurance. Moreover, permitting the adoption of insurance significantly enhances individual contributions and facilitates provision, especially when the required threshold is high. This work also relates the strategy competition outcomes to different allocation rules once the resulted contributions exceed the threshold point in populations nested within a dilemma.

‣ Evolution of All-or-None Strategies in Repeated Public Goods Dilemmas

Pinheiro, Flávio L.; Vasconcelos, Vítor V.; Santos, Francisco C.; Pacheco, Jorge M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 13/11/2014 Português
Relevância na Pesquisa
58.068213%
Many problems of cooperation involve repeated interactions among the same groups of individuals. When collective action is at stake, groups often engage in Public Goods Games (PGG), where individuals contribute (or not) to a common pool, subsequently sharing the resources. Such scenarios of repeated group interactions materialize situations in which direct reciprocation to groups may be at work. Here we study direct group reciprocity considering the complete set of reactive strategies, where individuals behave conditionally on what they observed in the previous round. We study both analytically and by computer simulations the evolutionary dynamics encompassing this extensive strategy space, witnessing the emergence of a surprisingly simple strategy that we call All-Or-None (AoN). AoN consists in cooperating only after a round of unanimous group behavior (cooperation or defection), and proves robust in the presence of errors, thus fostering cooperation in a wide range of group sizes. The principles encapsulated in this strategy share a level of complexity reminiscent of that found already in 2-person games under direct and indirect reciprocity, reducing, in fact, to the well-known Win-Stay-Lose-Shift strategy in the limit of the repeated 2-person Prisoner's Dilemma.

‣ Evolution of cooperation in multilevel public goods games with community structures

Wang, Jing; Wu, Bin; Ho, Daniel W. C.; Wang, Long
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/03/2011 Português
Relevância na Pesquisa
48.308457%
In a community-structured population, public goods games (PGG) occur both within and between communities. Such type of PGG is referred as multilevel public goods games (MPGG). We propose a minimalist evolutionary model of the MPGG and analytically study the evolution of cooperation. We demonstrate that in the case of sufficiently large community size and community number, if the imitation strength within community is weak, i.e., an individual imitates another one in the same community almost randomly, cooperation as well as punishment are more abundant than defection in the long run; if the imitation strength between communities is strong, i.e., the more successful strategy in two individuals from distinct communities is always imitated, cooperation and punishment are also more abundant. However, when both of the two imitation intensities are strong, defection becomes the most abundant strategy in the population. Our model provides insight into the investigation of the large-scale cooperation in public social dilemma among contemporary communities.; Comment: 6 pages, 4 figures, Accepted by EPL

‣ A general model of the public goods dilemma

Frank, Steven A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/12/2011 Português
Relevância na Pesquisa
58.74921%
An individually costly act that benefits all group members is a public good. Natural selection favors individual contribution to public goods only when some benefit to the individual offsets the cost of contribution. Problems of sex ratio, parasite virulence, microbial metabolism, punishment of noncooperators, and nearly all aspects of sociality have been analyzed as public goods shaped by kin and group selection. Here, I develop two general aspects of the public goods problem that have received relatively little attention. First, variation in individual resources favors selfish individuals to vary their allocation to public goods. Those individuals better endowed contribute their excess resources to public benefit, whereas those individuals with fewer resources contribute less to the public good. Thus, purely selfish behavior causes individuals to stratify into upper classes that contribute greatly to public benefit and social cohesion and to lower classes that contribute little to the public good. Second, if group success absolutely requires production of the public good, then the pressure favoring production is relatively high. By contrast, if group success depends weakly on the public good, then the pressure favoring production is relatively weak. Stated in this way...

‣ La lógica de la acción colectiva en la producción de bienes públicos escalares

León Medina, Francisco José
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2010 Português
Relevância na Pesquisa
48.61967%
En este artículo, abordamos las características distintivas de la lógica de la acción colectiva en la producción de bienes públicos escalares (bienes con puntos de provisión). En el primer apartado, presentamos las diferencias existentes entre las funciones de producción de bienes públicos continuos (BPC) y las de bienes públicos escalares (BPE). Tras formalizar la situación estratégica en la que los agentes se enfrentan a la producción de un BPE, abordamos sus diferencias teóricas con las situaciones en las que normalmente se ha formalizado la producción de bienes continuos (el dilema de prisionero de n-personas). En tercer lugar, presentamos los hallazgos experimentales más destacados sobre las variables que afectan al nivel de las contribuciones voluntarias y a las tasas de éxito en la producción de BPE. Por último, señalamos algunas razones teóricas y prácticas por las cuales creemos conveniente el desarrollo de la experimentación en juegos de producción de bienes escalares; In this paper, we explore the distinctive features of the logic of collective action in the production of step-level public goods. In the first part, we present the differences between the production functions of continuous public goods (here BPC) and those of the step-level public goods (here BPE). After formalizing the situation where the production of a BPE is pursued...