A New Era of Measurable Effects? Essays on Political Communication in the New Media Age

In this dissertation, I explore the ways in which traditional processes of opinion formation, media exposure, and mobilization operate in a networked, fragmented, and high-choice environment. From a methodological standpoint, one of the advantages of this shift toward Internet-mediated activity is the potential for enhanced measurement. In my dissertation, I take advantage of the data trail left by individuals in order to learn about political behavior and media effects online. Combining this measurement strategy with field experiments conducted in naturalistic online environments, I am able to shed light on how longstanding concerns in political science manifest themselves in the present-day media landscape. The overarching theme is that, thanks to advances in both research design and technology, many well-articulated concerns about the impact of the Internet on politics and public life can now be subjected to rigorous scrutiny. As I show here, the most dire predictions -- about people's tendency to cocoon themselves into ideological echo chambers or opt for low-cost "slacktivism" over more meaningful contributions to collective action -- appear to lack strong support. But it is also clear that results clearly depend on the structural features of a particular medium: Twitter enables peer effects and the mutual reinforcement of viewpoints, while the high-choice environment of the Web may inherently lead to moderation.