We investigate theoretically and experimentally the "crisis bargaining model", a dynamic game of two-sided incomplete information with player types drawn from a commonly known distribution. Within the experiment we elicited beliefs from players about their opponent's type using a quadratic scoring rule. We implement two treatments that vary a fixed terminal node payoff in the game, generating sharp comparative static predictions in both beliefs and strategies. We examine the relationship between beliefs and actions, which is not well understood in the empirical literature. We find that most beliefs and strategies are responsive to our treatments in the way predicted by theory, and that beliefs track departures from theoretical predictions about strategy choice. We highlight evidence for two deviations from Bayesian beliefs: conservative updating and motivated beliefs. We also consider other important roles for beliefs in strategic choice including the extent of rational expectations and best response to beliefs.
Traditionally in the social sciences, causal mediation analysis has been formulated, understood, and implemented within the framework of linear structural equation models. We argue and demonstrate that this is problematic for three reasons; the lack of a general definition of causal mediation effects independent of a particular statistical model, the inability to specify the key identification assumption, and the difficulty of extending the framework to nonlinear models. In this paper, we propose an alternative approach that overcomes these limitations. Our approach is general because it offers the definition, identification, estimation, and sensitivity analysis of causal mediation effects without reference to any specific statistical model. Further, our approach explicitly links these four elements closely together within a single framework. As a result, the proposed framework can accommodate linear and nonlinear relationships, parametric and nonparametric models, continuous and discrete mediators, and various types of outcome variables. The general definition and identification result also allow us to develop sensitivity analysis in the context of commonly used models, which enables applied researchers to formally assess the robustness of their empirical conclusions to violations of the key assumption. We illustrate our approach by applying it to the Job Search Intervention Study (JOBS II). We also offer easy-to-use software that implements all of our proposed methods.
Monoamine oxidase A gene (MAOA) has earned the nickname “warrior gene” because it has been linked to aggression in observational and survey-based studies. However, no controlled experimental studies have tested whether the warrior gene actually drives behavioral manifestations of these tendencies. We report an experiment, synthesizing work in psychology and behavioral economics, which demonstrates that aggression occurs with greater intensity and frequency as provocation is experimentally manipulated upwards, especially among low activity MAOA (MAOA-L) subjects. In this study, subjects paid to punish those they believed had taken money from them by administering varying amounts of unpleasantly hot (spicy) sauce to their opponent. There is some evidence of a main effect for genotype and some evidence for a gene by environment interaction, such that MAOA is less associated with the occurrence of aggression in a low provocation condition, but significantly predicts such behavior in a high provocation situation. This new evidence for genetic influences on aggression and punishment behavior complicates characterizations of humans as “altruistic” punishers and supports theories of cooperation that propose mixed strategies in the population. It also suggests important implications for the role of individual variance in genetic factors contributing to everyday behaviors and decisions.
Political science, as a discipline, has been reluctant to adopt theories and methodologies developed
in fields studying human behavior from an evolutionary standpoint. I ask whether evolutionary concepts are
reconcilable with standard political-science theories and whether those concepts help solve puzzles to which
these theories classically are applied. I find that evolutionary concepts readily and simultaneously accommodate
theories of rational choice, symbolism, interpretation, and acculturation. Moreover, phenomena
perennially hard to explain in standard political science become clearer when human interactions are
understood in light of natural selection and evolutionary psychology. These phenomena include the political
and economic effects of emotion, status, personal attractiveness, and variations in information-processing and
decision-making under uncertainty; exemplary is the use of ‘‘focal points’’ in multiple-equilibrium games. I
conclude with an overview of recent research by, and ongoing debates among, scholars analyzing politics in
evolutionarily sophisticated terms.