1,094 research outputs found
Punishment does not promote cooperation under exploration dynamics when anti-social punishment is possible
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.It has been argued that punishment promotes the evolution of cooperation when mutation rates are high (i.e. when agents engage in âexploration dynamicsâ). Mutations maintain a steady supply of agents that punish free-riders, and thus free-riders are at a disadvantage. Recent experiments, however, have demonstrated that free-riders sometimes also pay to punish cooperators. Inspired by these empirical results, theoretical work has explored evolutionary dynamics where mutants are rare, and found that punishment does not promote the evolution of cooperation when this âanti-social punishmentâ is allowed. Here we extend previous theory by studying the effect of anti-social punishment on the evolution of cooperation across higher mutation rates, and by studying voluntary as well as compulsory Public Goods Games. We find that for intermediate and high mutation rates, adding punishment does not promote cooperation in either compulsory or voluntary public goods games if anti-social punishment is possible. This is because mutations generate agents that punish cooperators just as frequently as agents that punish defectors, and these two effects cancel each other out. These results raise questions about the effectiveness of punishment for promoting cooperation when mutations are common, and highlight how decisions about which strategies to include in the strategy set can have profound effects on the resulting dynamics.O.P.H. is grateful to the department of Organismic and Evolutionary Biology at Harvard for fellowship support. Funding from the John Templeton Foundation is gratefully acknowledged
Cooperating with the future
This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Overexploitation of renewable resources today has a high cost on the welfare of future generations1,2,3,4,5. Unlike in other public goods games6,7,8,9, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the âIntergenerational Goods Gameâ. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting10,11,12,13,14,15 is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators16 that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.Financial support from the Department of Organismic and Evolutionary Biology at Harvard, the Harvard Office for Sustainability and the John Templeton Foundation is gratefully acknowledged
Think global, act local: Preserving the global commons
This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this recordPreserving global public goods, such as the planetâs 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 Prisonerâs Dilemma (PD) with their two nearest neighbours on a cyclic network after each PGG round. We observe that people engage in âlocal-to-globalâ reciprocity, leveraging local interactions to enforce global cooperation: Participants reduce PD cooperation with neighbours who contribute little in the PGG. In response, low PGG contributors increase their contributions if both neighbours defect in the PD. In a control condition, participants do not know their neighboursâ PGG contribution and thus cannot link play in the PD to the PGG. In the control we observe a sharp decline of cooperation in the PGG, while in the treatment condition global cooperation is maintained. In a second experiment, we demonstrate the scalability of this effect: in a 1,000-person PGG, participants in the treatment condition successfully sustain public contributions. Our findings suggest that this simple âlocal-to-globalâ intervention facilitates large-scale cooperation.This work was supported by Office of Naval Research grant N00014-16-1-2914 and by the John Templeton Foundation. The Program for Evolutionary Dynamics is supported in part by a gift from B Wu and Eric Larson
Lightweight Interactions for Reciprocal Cooperation in a Social Network Game
The construction of reciprocal relationships requires cooperative
interactions during the initial meetings. However, cooperative behavior with
strangers is risky because the strangers may be exploiters. In this study, we
show that people increase the likelihood of cooperativeness of strangers by
using lightweight non-risky interactions in risky situations based on the
analysis of a social network game (SNG). They can construct reciprocal
relationships in this manner. The interactions involve low-cost signaling
because they are not generated at any cost to the senders and recipients.
Theoretical studies show that low-cost signals are not guaranteed to be
reliable because the low-cost signals from senders can lie at any time.
However, people used low-cost signals to construct reciprocal relationships in
an SNG, which suggests the existence of mechanisms for generating reliable,
low-cost signals in human evolution.Comment: 13 pages, 2 figure
Sustainable institutionalized punishment requires elimination of second-order free-riders
Although empirical and theoretical studies affirm that punishment can elevate
collaborative efforts, its emergence and stability remain elusive. By
peer-punishment the sanctioning is something an individual elects to do
depending on the strategies in its neighborhood. The consequences of
unsustainable efforts are therefore local. By pool-punishment, on the other
hand, where resources for sanctioning are committed in advance and at large,
the notion of sustainability has greater significance. In a population with
free-riders, punishers must be strong in numbers to keep the "punishment pool"
from emptying. Failure to do so renders the concept of institutionalized
sanctioning futile. We show that pool-punishment in structured populations is
sustainable, but only if second-order free-riders are sanctioned as well, and
to a such degree that they cannot prevail. A discontinuous phase transition
leads to an outbreak of sustainability when punishers subvert second-order
free-riders in the competition against defectors.Comment: 7 two-column pages, 3 figures; accepted for publication in Scientific
Report
Generosity Pays in the Presence of Direct Reciprocity: A Comprehensive Study of 2Ă2 Repeated Games
By applying a technique previously developed to study ecosystem assembly [CapitĂĄn et al., Phys. Rev. Lett. 103, 168101 (2009)] we study the evolutionary stable strategies of iterated 22 games. We focus on memory-one strategies, whose probability to play a given action depends on the actions of both players in the previous time step. We find the asymptotically stable populations resulting from all possible invasions of any known stable population. The results of this invasion process are interpreted as transitions between different populations that occur with a certain probability. Thus the whole process can be described as a Markov chain whose states are the different stable populations. With this approach we are able to study the whole space of symmetric 22 games, characterizing the most probable results of evolution for the different classes of games. Our analysis includes quasi-stationary mixed equilibria that are relevant as very long-lived metastable states and is compared to the predictions of a fixation probability analysis. We confirm earlier results on the success of the Pavlov strategy in a wide range of parameters for the iterated Prisoner's Dilemma, but find that as the temptation to defect grows there are many other possible successful strategies. Other regions of the diagram reflect the equilibria structure of the underlying one-shot game, albeit often some non-expected strategies arise as well. We thus provide a thorough analysis of iterated 22 games from which we are able to extract some general conclusions. Our most relevant finding is that a great deal of the payoff parameter range can still be understood by focusing on win-stay, lose-shift strategies, and that very ambitious ones, aspiring to obtaining always a high payoff, are never evolutionary stable
Counterfactual thinking in cooperation dynamics
Counterfactual Thinking is a human cognitive ability studied in a wide
variety of domains. It captures the process of reasoning about a past event
that did not occur, namely what would have happened had this event occurred,
or, otherwise, to reason about an event that did occur but what would ensue had
it not. Given the wide cognitive empowerment of counterfactual reasoning in the
human individual, the question arises of how the presence of individuals with
this capability may improve cooperation in populations of self-regarding
individuals. Here we propose a mathematical model, grounded on Evolutionary
Game Theory, to examine the population dynamics emerging from the interplay
between counterfactual thinking and social learning (i.e., individuals that
learn from the actions and success of others) whenever the individuals in the
population face a collective dilemma. Our results suggest that counterfactual
reasoning fosters coordination in collective action problems occurring in large
populations, and has a limited impact on cooperation dilemmas in which
coordination is not required. Moreover, we show that a small prevalence of
individuals resorting to counterfactual thinking is enough to nudge an entire
population towards highly cooperative standards.Comment: 18 page
Quality versus quantity of social ties in experimental cooperative networks
Recent studies suggest that allowing individuals to choose their partners can help to maintain cooperation in human social networks; this behaviour can supplement behavioural reciprocity, whereby humans are influenced to cooperate by peer pressure. However, it is unknown how the rate of forming and breaking social ties affects our capacity to cooperate. Here we use a series of online experiments involving 1,529 unique participants embedded in 90 experimental networks, to show that there is a âGoldilocksâ effect of network dynamism on cooperation. When the rate of change in social ties is too low, subjects choose to have many ties, even if they attach to defectors. When the rate is too high, cooperators cannot detach from defectors as much as defectors re-attach and, hence, subjects resort to behavioural reciprocity and switch their behaviour to defection. Optimal levels of cooperation are achieved at intermediate levels of change in social ties
Cooperation and Contagion in Web-Based, Networked Public Goods Experiments
A longstanding idea in the literature on human cooperation is that
cooperation should be reinforced when conditional cooperators are more likely
to interact. In the context of social networks, this idea implies that
cooperation should fare better in highly clustered networks such as cliques
than in networks with low clustering such as random networks. To test this
hypothesis, we conducted a series of web-based experiments, in which 24
individuals played a local public goods game arranged on one of five network
topologies that varied between disconnected cliques and a random regular graph.
In contrast with previous theoretical work, we found that network topology had
no significant effect on average contributions. This result implies either that
individuals are not conditional cooperators, or else that cooperation does not
benefit from positive reinforcement between connected neighbors. We then tested
both of these possibilities in two subsequent series of experiments in which
artificial seed players were introduced, making either full or zero
contributions. First, we found that although players did generally behave like
conditional cooperators, they were as likely to decrease their contributions in
response to low contributing neighbors as they were to increase their
contributions in response to high contributing neighbors. Second, we found that
positive effects of cooperation were contagious only to direct neighbors in the
network. In total we report on 113 human subjects experiments, highlighting the
speed, flexibility, and cost-effectiveness of web-based experiments over those
conducted in physical labs
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