Marco Casari

Decentralized management of common property resources: experiments with a centuries-old institution

For centuries, villages in the Alps employed a special system for managing their common properties. Individual users could inspect other users at their own cost and impose a predetermined sanction (a fine) when a free rider was discovered. The fine was paid to the user who found a violator. Experiments with the institutions demonstrate that this mechanism considerably improves efficiency of resource use. The classical model of identical selfish agents does not capture the data as well as a model with heterogeneous and linear other-regarding preferences. Altruism and especially potentially dysfunctional behavior, such as spite and mistake, play important positive roles.

How groups reach agreement in risky choices: an experiment.

This paper studies how groups resolve disagreement in lottery choices. In an experiment, subjects submit individual proposals, exchange chat messages, and must reach unanimity. Overall, group choices are more coherent and closer to risk neutrality than individuals’. The proposal of the minority prevails in about one instance out of five. About one third of the groups do not reach immediate agreement after communication. In these groups, extrovert subjects are more likely to lead the group outcome than confused or conscientious subjects. The amount, equality and timing of chat messages help us to predict which choice prevails in the group.

Time Horizon and Cooperation in Continuous Time

When subjects interact in continuous time, their ability to cooperate may dramatically increase. In an experiment, we study the impact of different time horizons on cooperation in (quasi) continuous time prisoners dilemmas. We find that cooperation levels are similar or higher when the horizon is deterministic rather than stochastic. Moreover, a deterministic duration generates different aggregate patterns and individual strategies than a stochastic one. For instance, under a deterministic horizon subjects show high initial cooperation and a strong end-of-period reversal to defection. Moreover, they do not learn to apply backward induction but to postpone defection closer to the end.

Money and Trust Among Strangers

What makes money essential for the functioning of modern society? Through an experiment, we present evidence for the existence of a relevant behavioral dimension in addition to the standard theoretical arguments. Subjects faced repeated opportunities to help an anonymous counterpart who changed over time. Cooperation required trusting that help given to a stranger today would be returned by a stranger in the future. Cooperation levels declined when going from small to large groups of strangers, even if monitoring and payoffs from cooperation were invariant to group size. We then introduced intrinsically worthless tokens. Tokens endogenously became money: subjects took to reward help with a token and to demand a token in exchange for help. Subjects trusted that strangers would return help for a token. Cooperation levels remained stable as the groups grew larger. In all conditions, full cooperation was possible through a social norm of decentralized enforcement, without using tokens. This turned out to be especially demanding in large groups. Lack of trust among strangers thus made money behaviorally essential. To explain these results, we developed an evolutionary model. When behavior in society is heterogeneous, cooperation collapses without tokens. In contrast, the use of tokens makes cooperation evolutionarily stable.

Cooperative Strategies in Anonymous Economies: An Experiment

We study cooperation in economies of indefinite duration. Participants faced a sequence of prisonerʼs dilemmas with anonymous opponents. We identify and characterize the strategies employed at the individual level. We report that (i) grim trigger does not describe well individual play and there is wide heterogeneity in strategies; (ii) systematic defection does not crowd-out systematic cooperation; (iii) coordination on cooperative strategies does not improve with experience. We discuss alternative methodologies and implications for theory.

Amoral Familism, Social Capital, or Trust? The Behavioural Foundations of the Italian North-South Divide

We present the first laboratory‐in‐the field experiment on the Italian North–South divide. Using a representative sample of the population, we measure whether regional disparities in ability to cooperate emerge even if differences in geography, institutions and criminal intrusion are silenced. We report that a behavioural gap in cooperation exists: Northern and Southern citizens react differently to the same incentives. Moreover, this gap cannot be accounted for by tolerance for risk, proxies of social capital and ‘amoral familism’. At least a share of North–South disparities is likely to derive from persistent differences in social norms.

Communication, commitment, and deception in social dilemmas: experimental evidence

Social norms of cooperation are studied under several forms of communication. In an experiment, strangers could make public statements before playing a prisoner’s dilemma. The interaction was repeated indefinitely, which generated multiple equilibria. Communication could be used as a tool to either signal intentions to coordinate on Pareto-superior outcomes, to deceive others, or to credibly commit to actions. Some forms of communication did not promote the incidence of efficient Nash play, and sometimes reduced it. Surprisingly, cooperation suffered when subjects could publicly commit to actions.

Fragile Markets: An Experiment on Judicial Independence

Contract enforcement does not only affect single transactions but the market as a whole. We compare alternative institutions that allocate enforcement rights to the different parties to a credit transaction: either lenders, borrowers, or judges. Despite all parties having incentives to enforce and transact, the market flourishes or disappears depending on the treatment: paying judges according to lenders’ votes maximizes total surplus and equity; and a similar result appears when judges are paid according to average earnings in society. In contrast, paying judges according to borrowers’ votes generates the poorest and most unequal society. These results suggest that parties playing the role of borrowers understand poorly the systemic consequences of their decisions, triggering under-enforcement, and hence wasting profitable trade opportunities.In an experiment we study market outcomes under alternative incentive structures for thirdparty enforcers. Our transactions resemble an anonymous credit market where lenders can give loans and borrowers can repay them. When borrowers default, judges are free to enforce repayment but are themselves paid differently in each of three treatments. First, paying judges according to lenders’ votes maximizes surplus and the equality of earnings. In contrast, paying judges according to borrowers’ votes triggers insufficient enforcement, destroying the market and producing the lowest surplus and the most unequal distribution of earnings. Lastly, judges paid the average earnings of borrowers and lenders achieve results close to those based on lender voting. We employ a steps-of-reasoning argument to interpret the performances of different institutions. When voting and enforcement rights are allocated to different classes of actors, the difficulty of their task changes, and arguably as a consequence they focus on high or low surplus equilibria.

When Do Groups Perform Better Than Individuals? A Company Takeover Experiment

It is still an open question when groups perform better than individuals in intellectual tasks. We report that in a company takeover experiment, groups placed better bids than individuals and substantially reduced the winner’s curse. This improvement was mostly due to peer pressure over the minority opinion and to learning. Learning took place from interacting and negotiating consensus with others, not simply from observing their bids. When there was disagreement, what prevailed was not the best proposal but the one of the majority. Groups underperformed with respect to a “truth wins” benchmark although they outperformed individuals deciding in isolation.

Weak reciprocity alone cannot explain peer punishment

The claims about (1) the lack of empirical support for a model of strong reciprocation and (2) the irrelevant empirical role of costly punishment to support cooperation in the field need qualifications. The interpretation of field evidence is not straightforward, and other-regarding preferences are also likely to play a role in the field.