Doctor of Philosophy (PhD)


Manship School of Mass Communication

Document Type



This dissertation brings together the findings from three experimental studies that seek to understand how exposure to information in an online news aggregating portal can influence users’ perceptions of the relative importance of problems facing society. Theoretically, this investigation relies on two foundational ideas. One is that in today’s high-choice, multi-source media environment communication flows are curated by a variety of gatekeeping actors, such as algorithms and fellow users. Individuals can have varying attitudes toward and perceptions of these gatekeepers, which can influence the effects of exposure to online information, including agenda-setting outcomes. Another is that users of digital news, facing a nearly infinite supply of information, rely heavily on presentation cues embedded in news platforms’ interfaces to navigate the news landscape and make sense of the messages they encounter. These powerful features can communicate the identity of gatekeepers who curate the newsfeed, as well as particular mechanisms of curation.

Using the data from a longitudinal experiment where participants were exposed to a dynamic, constantly updated news portal populated with real news, the first study tests the comparative effects of two user-sourced cues representing different logics of content selection. The analysis does not support the expectation of differential agenda-setting effects, yet this finding could be the result of study design that did not allow for sufficient control of all the aspects of the treatment. The second experiment is a pilot test of an alternative experimental design that allows for a cleaner test of interface agenda cues’ differential effects. Its success in influencing users’ issue priorities paves the way for the main experiment that utilizes the same treatment mechanism. This study reveals that different types of interface agenda cues can influence users’ perceptions of issue importance differently in the news portal context. Consistent with the agenda cueing hypothesis, users high in gatekeeping trust are revealed to be especially susceptible to media agenda cues. In conclusion, I argue that interfaces of digital platforms should become the subject of public scrutiny, while news literacy interventions should focus on raising people’s awareness of how digital platforms aggregate and present the news.

Committee Chair

Pingree, Raymond