Legislating while Learning

This dissertation examines how legislators learn about policy proposals. It focuses on three common sources of policy information --- staff briefings, cues, and group deliberations --- to show the causal effect of information on legislators' policy positions. It uses a new approach, field experiments, that allows me to answer questions about information, institutions, and outcomes that heretofore have been difficult to study quantitatively. Results from the three studies I conducted are largely consistent with theories of legislating under imperfect information. All three studies find that information affects position-taking. On average, information increases support by reducing legislators' uncertainty. Information is most influential on bills that legislators are ideologically predisposed to support. In some respects, findings extend or challenge existing theories. Legislators appear responsive to repeated messaging. Cues and briefings interact to make legislators even more supportive of bills than we would expect from their separate effects. Cues determine a far greater proportion of positions than prior studies suggested. Finally, group deliberation appears to reduce partisan polarization in bill coalitions. All together, the studies illustrate that imperfect information constrains position-taking, that legislative staff, cue-taking, and deliberation can effectively communicate information, and that legislative institutions influence individual positions by providing policy-relevant information.