Does Celebrity Issue Advocacy Mobilize Issue Publics?

Case studies and correlational evidence suggest that celebrity political advocacy leads to media coverage and public attention. With a new dataset of celebrity witnesses at congressional hearings, we develop a systematic analysis that allows us to estimate whether celebrities increase media coverage of the issues they advocate in official government venues. We also use this dataset to measure how much celebrity advocacy efforts increase public engagement with policy issues—a necessary condition for the expansion of issue publics. We find that the issues addressed in congressional hearings featuring celebrity witnesses are about three times more likely to be the subject of the New York Times reporting, but the average celebrity witness has no discernible effect on public issue attention, as measured by Wikipedia page views. We conclude that while the Internet vastly expands the opportunities for political communication, it is difficult to appropriate non-political social network infrastructures to promote policy change