For many observers, experiments symbolize science. Young and old alike are drawn to science by visions of women and men (often in white coats) experimenting on new ideas. In sciences such as chemistry and psychology, the image is real. Although both disciplines contain theorists and nonexperimental researchers, most of their professional norms and great accomplishments are indescribable without reference to experimental methods. In such disciplines, experiments are the leading vehicle of knowledge creation.

Experiments offer a useful methodological tool to examine issues of importance to political scientists. The historical and cultural differences between experiments in behavioral economics and social psychology are discussed. Issues of central concern to experimentalists are covered, including impact versus control, mundane versus experimental realism, internal versus external validity, deception, and laboratory versus field experiments. Advantages and disadvantages of experimentation are summarized.

We advocate for an experimental approach to the study of personality and politics. In particular, we propose an “interactionist” model of political behavior in which the cognitive and behavioral effects of dispositional variables are qualified by experimentally induced contexts. Our operating assumption is that the political effects of personality do not occur in a contextual vacuum, but instead are magnified by the presence of key precipitating or “activating” features of the political environment. We illustrate the approach with four experimental studies of authoritarianism. Results indicate that the effects of authoritarianism depend critically on the presence of situationally induced threat. More generally, we argue that interactions between personality variables and experimental treatments can lead to valuable insights about when and why personality makes a meaningful contribution to public opinion and political behavior. Finally, we close with a critique of the traditional skepticism toward experimentation in political science, and suggest that external validity is an overrated virtue when the research goal is the development of theory rather than the description of “real-world” phenomena.

Some who have written about the logic of experimentation argue that random assignment of subjects to treatment conditions is an essential attribute of an experiment. Others disagree. Rather than treating this as a matter of dueling definitions, we consider experiments without randomization from a theoretical perspective. Our central contention here is that, for some research questions, theory dictates systematic (not random) assignment of respondents to experimental conditions. Two such areas of inquiry are research on political tolerance and on institutional legitimacy. This article gives cursory attention to the former body of work and detailed attention to the latter, based on an experiment conducted in a survey in 2001 on the consequences of the American presidential election for institutional legitimacy. Because in both instances theory requires nonrandom assignment, the problem becomes one of identifying the costs of nonrandomization (threats to internal validity) and specifying analytical techniques that might ameliorate those costs. Consequently, we present results from a statistical approach that addresses the problem of nonrandomization. The most important claim of this article is that theory ought to specify research design, including experimental designs, and that dogmatic attachment to one definition of experiment will not serve the discipline of political science.

The ultimatum game is a standard instrument for laboratory experimentalists. It has been replicated in a large number of environments and points to special considerations for fairness. Although it has been popular in the experimental community, researchers have not harnessed all the statistical power they should to evaluate the dynamics at work in this type of a bargaining game. This research uses two planned treatments, the first involving a signaling condition concerning a subject's “type”, and the second a price effect built into the structure of the game. We find that there are no significant main effects as a result of the signaling condition of a subject's type, but that there are strong effects as a result of the different payoff parameters. Using a variety of multivariate models we find important, nonobvious interactions with the gender of the subjects. The lesson that we take away from this research is that experimentalists can learn more from data collected in the tightly controlled laboratory environment by using statistical techniques that complement their research designs.

The debate about the cost-effectiveness of randomized field experimentation ignores one of the most important potential uses of experimental data. This article defines and illustrates “downstream” experimental analysis—that is, analysis of the indirect effects of experimental interventions. We argue that downstream analysis may be as valuable as conventional analysis, perhaps even more so in the case of laboratory experimentation.

In this study, we unite two experimental traditions to examine the impact of discursive processes on political decision making. We directly manipulate the presence and timing of discussion in the “divide-the-dollar” game to assess the effects of discussion on participants' allocations and perceptions of the game's legitimacy. To investigate the influence of structure, we also manipulate the presence of a majority/minority cleavage among participants. The dependent measures in all instances are the players' allocations, the outcome of the game, and psychometric indicators of legitimacy perceptions. Results indicate that the presence of discussion can generate outcomes that are perceived as more equitable and fair in some circumstances—namely, when a cleavage is present. These findings establish the utility of this paradigm, as well as an important baseline for assessing the probable impacts of proposals to integrate deliberation into political decision making.