How Media Storms and Topic Diversity Influence Agenda Fragmentation

Abstract

Political communication scholars have long warned of the danger of fragmented media agendas on public discourse and debate. This research develops a better understanding of agenda fragmentation in the American mass media by leveraging a data set of broadcast and partisan cable agendas over five years to examine the conditions under which agenda fragmentation, and agenda congruence, occurs. Using measures of agenda diversity and media storms, I demonstrate that agenda fragmentation is conditional on the broader media environment, with news outlets exhibiting congruence in agendas when coverage is skewed toward one or a few large issues and coverage that reverts to “niche” issue agendas during periods of time not characterized by issues that take up high levels of the agenda space. In particular, traditional broadcast sources show the effect over the broader media agenda, particularly when those sources exhibit media storm–type coverage. No similar effect is found for cable news sources. This research illuminates the conditional nature of agenda fragmentation and points the way forward for a more nuanced understanding of agendas in a diverse media ecology.