Sequential equilibrium in monotone games: theory-based analysis of experimental data

A monotone game is an extensive-form game with complete information, simultaneous moves and an irreversibility structure on strategies. It captures a variety of situations in which players make partial commitments and allows us to characterize conditions under which equilibria result in socially desirable outcomes. However, since the game has many equilibrium outcomes, the theory lacks predictive power. To produce stronger predictions, one can restrict attention to the set of sequential equilibria, or Markov equilibria, or symmetric equilibria, or pure-strategy equilibria. This paper explores the relationship between equilibrium behavior in a class of monotone games, namely voluntary contribution games, and the behavior of human subjects in an experimental setting. We find evidence of both pure- and mixed-strategy equilibria and several key features of the symmetric Markov perfect equilibrium (SMPE) in the data. To judge how well the SMPE fits the data, we estimate a model of Quantal Response Equilibrium (QRE) (McKelvey and Palfrey 1995, 1998) and find that the decision rules of the QRE model are qualitatively very similar to the empirical choice probabilities

Social preferences of future physicians.

We measure the social preferences of a sample of US medical students and compare their preferences with those of the general population sampled in the American Life Panel (ALP). We also compare the medical students with a subsample of highly educated, wealthy ALP subjects as well as elite law school students and undergraduate students. We further associate the heterogeneity in social preferences within medical students to the tier ranking of their medical schools and their expected specialty choice. Our experimental design allows us to rigorously distinguish altruism from preferences regarding equality-efficiency tradeoffs and accurately measure both at the individual level rather than pooling data or assuming homogeneity across subjects. This is particularly informative, because the subjects in our sample display widely heterogeneous social preferences in terms of both their altruism and equality-efficiency tradeoffs. We find that medical students are substantially less altruistic and more efficiency focused than the average American. Furthermore, medical students attending the top-ranked medical schools are less altruistic than those attending lower-ranked schools. We further show that the social preferences of those attending top-ranked medical schools are statistically indistinguishable from the preferences of a sample of elite law school students. The key limitation of this study is that our experimental measures of social preferences have not yet been externally validated against actual physician practice behaviors. Pending this future research, we probed the predictive validity of our experimental measures of social preferences by showing that the medical students choosing higher-paying medical specialties are less altruistic than those choosing lower-paying specialties

Network architecture, salience and coordination

This paper reports the results of an experimental investigation of monotone games with imperfect information. Players are located at the nodes of a network and observe the actions of other players only if they are connected by the network. These games have many sequential equilibria; nonetheless, the behavior of subjects in the laboratory is predictable. The network architecture makes some strategies salient and this in turn makes the subjects’ behavior predictable and facilitates coordination on efficient outcomes. In some cases, modal behavior corresponds to equilibrium strategies

Broken Telephone: Analysis of a Reinforced Process

We consider the following $L$ player co-operative signaling game. Nature plays from the set $\{0,0\u27\}$. Nature\u27s play is observed by Player 1 who then plays from the set $\{1,1\u27\}$. Player 1\u27s play is observed by Player 2. Player 2 then plays from the set $\{2,2\u27\}$. Player 2\u27s play is observed by player 3. This continues until Player L observes Player L-1\u27s play. Player L then guesses Nature\u27s play. If he guesses correctly, then all players win. We consider an urn scheme for this where each player has two urns, labeled by the symbols they observe. Each urn has balls of two types, represented by the two symbols the player controlling the urn is allowed to play. At each stage each player plays by drawing from the appropriate urn, with replacement. After a win each player reinforces by adding a ball of the type they draw to the urn from which it was drawn. We attempt to show that this type of urn scheme achieves asymptotically optimal coordination. A lemma remains unproved but we have good numerical evidence for it\u27s truth

Distinguishing Social Preferences from Preferences for Altruism

We report a laboratory experiment that enables us to distinguish preferences for altruism (concerning tradeoffs between own payoffs and the payoffs of others) from social preferences (concerning tradeoffs between the payoffs of others). By using graphical representations of three-person Dictator Games that vary the relative prices of giving, we generate a very rich data set well-suited to studying behavior at the level of the individual subject. We attempt to recover subjects’ underlying preferences by estimating a constant elasticity of substitution (CES) model that represents altruistic and social preferences. We find that both social preferences and preferences for altruism are highly heterogeneous, ranging from utilitarian to Rawlsian. In spite of this heterogeneity across subjects, there exists a strong positive withinsubject correlation between the efficiency-equity tradeoffs made in altruistic and social preferences.

Individual Preferences for Giving

This paper reports an experimental test of individual preferences for giving. We use graphical representations of modified Dictator Games that vary the price of giving. This generates a very rich data set well- suited to studying behavior at the level of the individual subject. We test the data for consistency with preference maximization, and we recover underlying preferences and forecast behavior using both nonparametric and parametric methods. Our results emphasize that classical demand theory can account surprisingly well for behaviors observed in the laboratory and that individual preferences for giving are highly heterogeneous, ranging from utilitarian to Rawlsian to perfectly selfish.Experiment, Fairness, Dictator Game, and Revealed Preference

Network Architecture and Mutual Monitoring in Public Goods Experiments

Recent experiments show that public goods can be provided at high levels when mutual monitoring and costly punishment are allowed. All these experiments, however, study monitoring and punishment in a setting where all agents can monitor and punish each other (i.e., in a complete network). The architecture of social networks becomes important when individuals can only monitor and punish the other individuals to whom they are connected by the network. We study several non-trivial network architectures that give rise to their own distinctive patterns of behavior. Nevertheless, a number of simple, yet fundamental, properties in graph theory allow us to interpret the variation in the patterns of behavior that arise in the laboratory and to explain the impact of network architecture on the efficiency and dynamics of the experimental outcomes.experiment, networks, public good, monitoring, punishment

Consistency, Heterogeneity, and Granularity of Individual Behavior under Uncertainty

By using graphical representations of budget sets over bundles of state-contingent commodities, we generate a very rich data set well-suited to studying behavior under uncertainty at the level of the individual subject. We test the data for consistency with the maximization hypothesis, and we estimate preferences using a two-parameter utility function based on Faruk Gul (1991). This specification provides a good interpretation to the data at the level of the individual subject and can account for the highly heterogeneous behaviors observed in the laboratory. The parameter estimates jointly describe attitudes toward risk and allow us to characterize the distribution of risk preferences in the population.uncertainty, revealed preference, Expected Utility Theory, loss/disappointment aversion, experiment

Who Is (More) Rational?

Revealed preference theory o¤ers a criterion for decision-making quality: if decisions are high quality then there exists a utility function that the choices maximize. We conduct a large-scale ?eld experiment that enables us to test subjects?choices for consistency with utility maximization and to combine the experimental data with a wide range of individual socioeco-nomic information for the subjects. There is considerable heterogeneity in subjects?consistency scores: high-income and high-education subjects display greater levels of consistency than low- income and low-education subjects, men are more consistent than women, and young subjects are more consistent than older subjects. We also ?nd that consistency with utility maximization is strongly related to wealth: a standard deviation increase in the consistency score is associated with 15-19 percent more wealth. This result conditions on socioeconomic variables including current income, education, and family structure, and is little changed when we add controls for past income, risk tolerance and the results of a standard personality test used by psychologists.