Digital gatekeepers have greatly shaped the gatekeeping process of news consumption and news engagement, but how digital gatekeepers work is understudied. This study focuses on one example of digital gatekeepers, trending topics on social media, which aggregate the most popular search terms and present them to the public. We utilize a natural experiment on Weibo by analyzing user engagement data of 36,239 posts in three consecutive weeks, during which trending topics were removed for 1 week. We show that trending topics implemented two layers of gatekeeping: trending topics increased user engagement with top news posts within each news outlet and widened the engagement gap between popular posts and less popular ones (intra-outlet gatekeeping), and the increases in engagement with top news items were most salient among the least popular news outlets, thus reducing the inequality among outlets (inter-outlet gatekeeping).
"The Importance of Trending Topics in the Gatekeeping of Social Media News Engagement: A Natural Experiment on Weibo." Communication Research, 2020.