Identifying and Understanding Social Media Gatekeepers: A Case Study of Gatekeepers for Immigration Related News on Twitter.

Social media has become an important source where people gather and communicate news. Prior studies in conventional mass media suggest that gatekeepers play an important role in the production of news messages. Despite the initial claim of social media being a place of democratized participation, we now know, social media is not free of gatekeepers either. However, it is unclear who social media gatekeepers are, how to identify them, and most importantly how do they impact news content production and dissemination. Due to fundamental differences between the structure and workings of social media vs. traditional media, what we know from mass media cannot directly apply in the context of social media. To answer these questions, we propose an actionable definition of social media gatekeepers backed by literature on news reporting in social media and traditional mass media. We then present a case study of identifying gatekeepers on Twitter at scale, using a set of 70k Twitter users interested in the news topic of "immigration''. The results of our mixed research approach highlight that, unlike the general Twitter users, the Twitter gatekeepers are often self-determining citizen journalists who manage their media presentation strategically. Moreover, Twitter gatekeepers tend to exhibit behavior mostly in accordance with the journalism norms and they contribute to and guard the truthfulness and neutrality of content.