Ð Regulations that are designed to improve social welfare typically begin with the premise that individuals are purely self-interested. Experimental evidence shows, however, that individuals do not typically behave this way; instead, they tend to strike a balance between self and group interests. From experiments performed in rural Colombia, we found that a regulatory solution for an environmental dilemma that standard theory predicts would improve social welfare clearly did not. This occurred because individuals confronted with the regulation began to exhibit less other-regarding behavior and made choices that were more self-interested; that is, the regulation appeared to crowd out other-regarding behavior.

The literature on noncompliant firms in transferable emissions permit systems offers little guidance to policymakers that must determine how to commit resources to monitor firms and punish violations in such systems. We consider how a budget-constrained enforcement autl1ority that seeks to minimize aggregate noncompliance in a transferable emissions permit system should allocate its monitoring and enforcement efforts among heterogeneous firms. With a conventional model of firm behavior in a transferable permit system, we find that differences in the allocation of monitoring and enforcement effort between any two types of firms should be independent of differences in their exogenous characteristics.

JEL classification: C93 D64 H41 Q20 C70Keywords: Altruism Common pool resources Conformity Experiments Reciprocity a b s t r a c t This paper develops and tests several models of pure Nash strategies of individuals who extract from a common pool resource when they are motivated by a combination of selfinterest and preferences for altruism, reciprocity, inequity aversion, or conformity. Using data from experiments conducted in three regions of Colombia that depend critically on a local fishery, we test whether an econometric summary of the subjects' pure Nash strategies is consistent with one or more of these models. We find that a model that balances selfinterest with a strong preference for conformity best describes average strategies.

Global climate change and fuel security risks have encouraged international and regional adoption of pollution/carbon taxes. A major portion of such policy interventions is directed at the electric power industry with taxes applied according to the type of fuel used by the power generators in their power plants. This paper proposes an electric power supply chain network model that captures the behavior of power generators faced with a portfolio of power plant options and subject to pollution taxes. We demonstrate that this general model can be reformulated as a transportation network equilibrium model with elastic demands and qualitatively analyzed and solved as such. The connections between these two different modeling schemas is done through finite-dimensional variational inequality theory. The numerical examples illustrate how changes in the pollution/carbon taxes affect the equilibrium electric power supply chain network production outputs, the transactions between the various decision-makers the demand market prices, as well as the total amount of carbon emissions generated.

A large, but inconclusive, literature addresses how economic heterogeneity affects the use of local resources and local environmental quality. One line of thought, which derives from Nash equilibrium provision of public goods, suggests that in contexts in which individual actions degrade local environmental quality, wealthier people in a community will tend to do more to protect environmental quality. In this paper we report on experiments performed in rural Colombia that were designed to explore the role that economic inequality plays in the 'provision' of local environmental quality. Subjects were asked to decide how much time to devote to collecting firewood from a local forest, which degrades local water quality, and how much to unrelated pursuits. Economic heterogeneity was introduced by varying the private returns to these alternative pursuits. Consistent with the Nash equilibrium prediction, we found that the players with more valuable alternative options put less pressure on local water quality. However, the subjects with less valuable alternative options showed significantly more restraint relative to their pure Nash strategies. Furthermore, they were willing to bear significantly greater opportunity costs to move their groups to outcomes that yielded higher average payoffs and better water quality than the Nash equilibrium outcome.