Who to punish? Individual decisions and majority rule in mitigating the free rider problem

We study a voluntary contributions mechanism in which punishment may be allowed, depending on subjects’ voted rules. We found that out of 160 group votes, even when groups had no prior experience with unrestricted punishment, no group ever voted to allow unrestricted punishment and no group ever allowed punishment of high contributors. Over a series of votes and periods of learning we found a distinct reluctance to allow any punishment at the beginning, with a gradual but clear evolution toward allowing punishment of low contributors. And groups allowing punishment of only low contributors achieved levels of cooperation and efficiency that are among the highest in the literature on social dilemmas.     

Quasi-option value under strategic interactions

We consider a simple two-period model of irreversible investment under strategic interactions between two players. In this setup, we show that the quasi-option value may cause some conceptual difficulties. In case of asymmetric information, decentralized investment decisions fail to induce first-best allocations. Therefore a regulator may not be able to exercise the option to delay the decision to develop. We also show that information-induced inefficiency may arise in a game situation and that under certain assumptions inefficiency can be eliminated by sending asymmetric information to the players, even when the regulator faces informational constraints. Our model is potentially applicable to various global environmental problems.     

Collusion, Delegation and Supervision with Soft Information

This paper shows that supervision with soft information is valuable whenever supervisors and supervisees collude under asymmetric information and proceeds then to derive an Equivalence Principle between organizational forms of supervisory and productive activities. We consider an organization with an agent privately informed on his productivity and a risk averse supervisor getting signals on the agent's type. In a centralized organization, the principal can communicate and contract with both the supervisor and the agent. However, these two agents can collude against the principal. In a decentralized organization, the principal only communicates and contracts with the supervisor who in turn sub-contracts with the agent. We show that the two organizations achieve the same outcome. We discuss this equivalence and provide various comparative statics results to assess the efficiency of supervisory structures.     

On the duality between prior beliefs and trading demands

In an abstract model with asymmetric information, we show that there is a duality relationship between the prior beliefs and trading demands of bets for any given individual. Then we aggregate all the agents to obtain a second duality relationship between common prior beliefs and trading possibilities. We easily derive from these relationships the no trade theorem and its converse. General efficiency results can be obtained. Moreover, our framework is sufficiently general to cover special cases proved previously (for example, Econometrica 62 (1994) 1327; Discussion Paper 83, Center for Rationality and Interactive Decision Theory, The Hebrew University of Jerusalem, 1995; J. Econom. Theory 91 (2000) 127; Games Econom. Behav. 24 (1998) 172. Yet, our arguments are both simple and intuitive.     

Endogenous formation of multiple social groups

This paper explores a model of group membership formation in which agents decide to join or not multiple social groups. The membership formation process induces a bipartite graph structure with social groups listed on one side and agents listed on the other side. Among members of multiple social groups, we consider two decisive types of agents: the grand star and the mini star. The former type is the unique agent in a society who participates in all social groups. The latter type includes agents who participate in more than one, but not all, social groups such that every social group pair has one and only one common member. We analyze the efficiency and stability conditions of group membership formation, and we establish sufficient conditions under which a connected graph that contains either a grand star or a set of mini stars becomes the unique strongly efficient and stable graph.     

Renewable resource management, user heterogeneity, and the scope for cooperation

Cooperation can increase the efficiency of commonly-owned renewable resource use. However, received knowledge is that, absent side payments, cooperative solutions are more difficult to achieve the less homogenous the agents involved. We revisit this claim by analyzing how differences in the opportunity costs of resource harvesting affect the scope for Pareto-improving contracts, where contracting is with respect to the type of technology used. We find that the scope for cooperation is largest for intermediate levels of heterogeneity.     

Markov-perfect Nash equilibria in a class of resource games

Summary. A general model of non-cooperating agents exploiting a renewable resource is considered. Assuming that the resource is sufficiently productive we prove that there exists a continuum of Markov-perfect Nash equilibria (MPNE). Although these equilibria lead to over-exploitation one can approximate the efficient solution by MPNE both in the state space and the payoff space. Furthermore, we derive a necessary and sufficient condition for maximal exploitation of the resource to qualify as a MPNE. This condition is satisfied if there are sufficiently many players, or if the players are sufficiently impatient, or if the capacity of each player is sufficiently high.Received: November 1, 1996This revised version was published online in February 2005 with corrections to the cover date.     

Producer price adjustment to commodity price shocks: An application of threshold cointegration

During the 1980s and 1990s, most developing countries in Sub-Saharan Africa and Latin America implemented structural adjustment reforms, which included the liberalization of export crop markets and the abolition of marketing boards. The emergence of new marketing systems may have altered price transmission mechanisms, especially if collusion behaviors have appeared among domestic stakeholders along the marketing chain. I use threshold cointegration tools to analyze the dynamics of world price transmission to coffee growers in three deregulated markets. The methods I use allow me to test the presence of a threshold in both the cointegrating relationship and its corresponding error correction model. Over the pre-reform period, I detect asymmetric price adjustments that appear favorable to producers - deviations from the long-run equilibrium resulting from largest increases in world prices being eliminated relatively quickly - and disappear in the post-reform period. On the contrary over the post-reform period, the results suggest that largest decreases in world prices may be transmitted relatively quickly to growers. These results can be seen as expressions of a favorable pricing policy over the pre-reform period and an unfavorable influence of new private agents over the post-reform period, meaning that in some cases reforms may have failed to create competitive market structures.     

Environmental variability and collective action: Experimental insights from an irrigation game

Studies of collective action in commons dilemmas in social–ecological systems typically focus on scenarios in which actors all share symmetric (or similar) positions in relation to the common-pool resource. Many common social–ecological systems do not meet these criteria, most notably, irrigation systems. Participants in irrigation systems must solve two related collective action problems: 1) the provisioning of physical infrastructure necessary to utilize the resource (water), and 2) the asymmetric common-pool resource dilemma where the relative positions of “head-enders” and “tail-enders” generate asymmetric access to the resource itself (water). In times of scarcity, head-enders have an incentive to not share water with tail-enders. Likewise, tail-enders have an incentive to not provide labor to maintain the system if they do not receive water. These interdependent incentives may induce a cooperative outcome under favorable conditions. However, how robust is this system of interdependent incentives in the presence of environmental variability that generates uncertainty about water availability either through variation in the water supply itself or through shocks to infrastructure? This paper reports on results from laboratory experiments designed to address this question.     

The impact of culture and ecology on cooperation in a common-pool resource experiment

Context affects decision-making in many ways. In this paper we explore differences in cooperation behaviour between communal farmers in Namibia and South Africa, who share the same ethnic origin but have had different historical and ecological constraints. We report on a series of field experiments based on a common-pool resource model. Our experimental design is framed according to the grazing situation in semi-arid rangelands. Dependent on the behaviour in previous rounds, participants are facing different states of resource availability with varying need to cooperate, coordinate and to be patient. While only 4% of the grazing areas in South Africa remain in good quality, Namibians achieve a level of 42%. We analyse the different experimental states and find that Namibians behave in all states more cooperatively. We argue that the large difference between the two regions is due to a combination of different historical developments and ecological preconditions: Namibian resource users have a longer experience in cooperative resource management and intact traditional norms. Moreover, the real-life payoffs to cooperation are higher in Namibia stemming from ecological factors.     

Field experiments in economics: The past, the present, and the future

This study presents an overview of modern field experiments and their usage in economics. Our discussion focuses on three distinct periods of field experimentation that have influenced the economics literature. The first might well be thought of as the dawn of “field” experimentation: the work of Neyman and Fisher, who laid the experimental foundation in the 1920s and 1930s by conceptualizing randomization as an instrument to achieve identification via experimentation with agricultural plots. The second, the large-scale social experiments conducted by government agencies in the mid-twentieth century, moved the exploration from plots of land to groups of individuals. More recently, the nature and range of field experiments has expanded, with a diverse set of controlled experiments being completed outside of the typical laboratory environment. With this growth, the number and types of questions that can be explored using field experiments has grown tremendously. After discussing these three distinct phases, we speculate on the future of field experimental methods, a future that we envision including a strong collaborative effort with outside parties, most importantly private entities.     

Bargaining and network structure: An experiment

We consider bargaining in a bipartite network of buyers and sellers, who can only trade with the limited number of people with whom they are connected. We perform an experimental test of a graph-theoretic model that yields unique predictions about equilibrium prices for the networks in our sessions. The results diverge sharply depending on how a connection is made between two separate simple networks, typically conforming to the theoretical directional predictions. Payoffs can be systematically affected even for agents who are not connected by the new link, and we find evidence of a form of social learning.     

Policy instruments for evolution of bounded rationality: Application to climate-energy problems

We demonstrate how an evolutionary agent-based model can be used to evaluate climate policies that take the heterogeneity of strategies of individual agents into account. An essential feature of the model is that the fitness of an economic strategy is determined by the relative welfare of the associated agent as compared to its immediate neighbors in a social network. This enables the study of policies that affect relative positions of individuals. We formulate two innovative climate policies, namely a prize, altering directly relative welfare, and advertisement, which influences the social network of interactions. The policies are illustrated using a simple model of global warming where a resource with a negative environmental impact—fossil energy—can be replaced by an environmentally neutral yet less cost-effective alternative, namely renewable energy. It is shown that the general approach enlarges the scope of economic policy analysis.     

Knowledge flows and the geography of networks: A strategic model of small world formation

This paper aims to demonstrate that the strategic approach to link formation can generate networks that share some of the main structural properties of most real social networks. For this purpose, we introduce a spatialized variation of the Connections model [Jackson, M.O., Wolinsky, A., 1996. A strategic model of social and economic networks. Journal of Economic Theory 71, 44–74] to describe the strategic formation of links by agents who balance the benefits of forming links resulting from imperfect knowledge flows against their costs, which increase with geographic distance. We show, for intermediate levels of knowledge transferability, clustering occurs in geographical space and a few agents sustain distant connections. Such networks exhibit the small world property (high clustering and short average relational distances). When the costs of link formation are normally distributed across agents, asymmetric degree distributions are also obtained.     

Resource-grabbing by status-conscious agents

We introduce a dynamic model of resource-grabbing by status-conscious agents, i.e., agents value not only their absolute consumption levels, but also the relative status within their reference group. We explore the effect of the concern for relative consumption on the growth rate and the welfare of an economy where agents appropriate from a common property resource. Our model shows that the greater is agents' concern about their relative status, the more aggressively they tend to behave. Consequently, social welfare is lower because the growth rate of the public asset is reduced due to higher extraction rate. We also consider the effect of increased heterogeneity, and show that social welfare decreases as the distribution of status-consciousness among agents widens.     

Income distribution, efficiency and rationing

This paper studies the impacts of income distribution on the efficiency of trade mechanism and rationing of agents who are priced out of trade in a dynamic search model with two-sided asymmetric information. Buyers and sellers have asymmetric information about valuations and incomes respectively. In such a frictional environment, the effects of several variants of changes in income distribution on efficiency of trading mechanism and the population of rationed buyers and sellers are elaborated.     

Perfect competition in asymmetric information economies: compatibility of efficiency and incentives

The idea of perfect competition for an economy with asymmetric information is formalized via an idiosyncratic signal process in which the private signals of almost every individual agent can influence only a negligible group of agents, and the individual agents’ relevant signals are essentially pairwise independent conditioned on the true states of nature. Thus, there is no incentive for an individual agent to manipulate her private information. The existence of incentive compatible, ex post Walrasian allocations is shown for such a perfectly competitive asymmetric information economy with or without “common values”. Consequently, the conflict between incentive compatibility and Pareto efficiency is resolved exactly, and its asymptotic version is derived for a sequence of large, but finite private information economies.     

The effects of heterogeneous interaction and risk attitude adaptation on the evolution of cooperation

This paper addresses the evolution of cooperation in a multi-agent system with agents interacting heterogeneously with each other based on the iterated prisoner’s dilemma (IPD) game. The heterogeneity of interaction is defined in two models. First, agents in a network are restricted to interacting with only their neighbors (local interaction). Second, agents are allowed to adopt different IPD strategies against different opponents (discriminative interaction). These two heterogeneous interaction scenarios are different to the classical evolutionary game, in which each agent interacts with every other agent in the population by adopting the same strategy against all opponents. Moreover, agents adapt their risk attitudes while engaging in interactions. Agents with payoffs above (or below) their aspirations will become more risk averse (or risk seeking) in subsequent interactions, wherein risk is defined as the standard deviation of one-move payoffs in the IPD game. In simulation experiments with agents using only own historical payoffs as aspirations (historical comparison), we find that the whole population can achieve a high level of cooperation via the risk attitude adaptation mechanism, in the cases of either local or discriminative interaction models. Meanwhile, when agents use the population’s average payoff as aspirations (social comparison) for adapting risk attitudes, the high level of cooperation can only be sustained in a portion of the population (i.e., partial cooperation). This finding also holds true in both of the heterogeneous scenarios. Considering that payoffs cannot be precisely estimated in a realistic IPD game, simulation experiments are also conducted with a Gaussian disturbance added to the game payoffs. The results reveal that partial cooperation in the population under social comparison is more robust to the variation in payoffs than the global cooperation under historical comparison.     

Reprint of: A common-pool resource experiment with postgraduate subjects from 41 countries

This study reports results from a new series of experiments that examine the robustness of face-to-face communication as a cooperation-facilitating institution in common-pool resource settings. Results are reported from nine experiment sessions, initially designed for pedagogical purposes. The sessions were conducted between 1998 and 2007 as part of a series of summer institutes on institutional analysis and environmental change. Subjects were graduate students and professionals from diverse disciplines, representing 41 countries of residence. The participants in this study stand in sharp contrast to most previous studies, which used undergraduates who self-select into experiments by volunteering to participate. Results from these experiments substantiate earlier findings that non-binding communication can serve as an effective mechanism for solving social dilemma problems, with subjects achieving near socially efficient outcomes.     

Taxation,redistribution, and observability in social dilemmas

In the presence of social dilemmas, cooperation is more difficult to achieve when populations are heterogeneous because of conflicting interests within groups. We examine cooperation in the context of a nonlinear common pool resource game, in which individuals have unequal extraction capacities and have to decide on their extraction of resources from the common pool. We introduce monetary and nonmonetary mechanisms in this environment. The two monetary mechanisms are tax extraction and redistribution of the tax revenue. These include a Pigovian per‐unit tax mechanism and an increasing block tax that only taxes units extracted above the social optimum. Another mechanism varies the observability of individual decisions. We find that the two tax and redistribution mechanisms reduce extraction, increase efficiency, and decrease inequality within groups. In contrast, observability impacts only the baseline condition by encouraging free‐riding instead of creating moral pressure to cooperate.