Division of the Humanities and Social Sciences California Institute of Technology Pasadena, California 91125 Correlated Equilibria in Voter Turnout Games

Communication is fundamental to elections. This paper extends canonical voter turnout models to include any form of communication, and characterizes the resulting set of correlated equilibria. In contrast to previous research, high-turnout equilibria exist in large electorates and uncertain environments. This difference arises because communication can be used to coordinate behavior in such a way that voters find it incentive compatible to always follow their signals past the communication stage. The equilibria have expected turnout of at least twice the size of the minority for a wide range of positive voting costs, and show intuitive comparative statics on turnout: it varies with the relative sizes of different groups, and decreases with the cost of voting. This research provides a general micro foundation for group-based theories of voter mobilization, or voting driven by communication on a network.