Investigations of networked public spheres often examine the structures of online platforms by studying users’ interactions. These works suggest that users’ interactions can lead to cyberbalkanization when interlocutors form homophilous communities that typically have few connections to others with opposing ideologies. Yet, rather than assuming communities are isolated, this study examines community-level interactions to reveal how communities in online discourses are more interdependent than previously theorized. Specifically, we examine how such interactions influence the evolution of topics overtime in source and target communities. Our analysis found that (a) the size of a source community (the community that initiates interactions) and a target community (the community that receives interactions), (b) the stability of the source community, and (c) the volume of mentions from a source community to a target community predicts the level of influence one community has on another’s discussion topics. We argue this has significant theoretical and practical implications. Lay Summary Political discussions online, especially those in the United States, seem to range between harmonious discussions of likeminded people and heated debates that end with few, if any, who have changed their minds. Researchers have often examined these balkanized/polarized situations by studying online communities as isolated echo chambers of opinion. Our study focuses on the interactions between online communities who have different worldviews. We examine communities engaged in the global refugee crisis. We consider how the inter-community interactions influence the agenda of the respective communities. Our longitudinal analysis on the one hand confirms previous studies, namely that intra-community interactions indeed resemble echo chambers. On the other hand, we also find that there is interdependence in the inter-community discussion topics, albeit some communities had greater influence on other communities’ discussion topics. For example, larger, more stable communities command more influence.

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网络公共领域相互依存的影响：社区层面的互动如何影响在线话语主题的演变

对网络公共领域的调查通常通过研究用户的交互来检查在线平台的结构。这些作品表明，当对话者形成通常与具有相反意识形态的其他人几乎没有联系的同质社区时，用户的互动可能导致网络巴尔干化。然而，本研究并没有假设社区是孤立的，而是研究了社区层面的互动，以揭示在线话语中的社区如何比以前理论化的更相互依存。具体来说，我们研究了这种交互如何影响源社区和目标社区中主题超时的演变。我们的分析发现（a）源社区（发起交互的社区）和目标社区（接收交互的社区）的规模，（b）源社区的稳定性，(c) 从源社区到目标社区的提及量预测了一个社区对另一个社区的讨论主题的影响程度。我们认为这具有重要的理论和实践意义。总结 在线政治讨论，尤其是在美国的政治讨论，似乎介于志同道合的人的和谐讨论和以少数人（如果有的话）改变主意的激烈辩论之间。研究人员经常通过将在线社区研究为孤立的意见回声室来研究这些两极分化/两极分化的情况。我们的研究侧重于具有不同世界观的在线社区之间的互动。我们考察了参与全球难民危机的社区。我们考虑社区间的互动如何影响各自社区的议程。一方面，我们的纵向分析证实了以前的研究，即社区内的相互作用确实类似于回声室。另一方面，我们也发现社区间讨论话题存在相互依存关系，尽管一些社区对其他社区讨论话题的影响更大。例如，更大、更稳定的社区拥有更大的影响力。