Previous research has documented the existence of both online echo chambers and hostile intergroup interactions. In this paper, we explore the relationship between these two phenomena by studying the activity of 5.97M Reddit users and 421M comments posted over 13 years. We examine whether users who are more engaged in echo chambers are more hostile when they comment on other communities. We then create a typology of relationships between political communities based on whether their users are toxic to each other, whether echo chamber-like engagement with these communities is associated with polarization, and on the communities' political leanings. We observe both the echo chamber and hostile intergroup interaction phenomena, but neither holds universally across communities. Contrary to popular belief, we find that polarizing and toxic speech is more dominant between communities on the same, rather than opposing, sides of the political spectrum, especially on the left; however, this mainly points to the collective targeting of political outgroups.

翻译：先前的研究记录了在线回声室和敌对群体间互动的存在。在本文中,我们通过研究5.97M Reddit用户的活动和13年来发布的421M评论来探讨这两种现象之间的关系。我们研究更多参与回声室的用户在评论其他社区时是否更加敌对。然后我们根据这些用户是否相互有毒、与这些社区进行类似回声室的接触是否与两极分化有关,以及这些社区的政治倾向,在政治社区之间建立了一种关系类型。我们观察回声室和敌对群体间互动现象,但没有在社区之间普遍存在。与公众的信念相反,我们发现两极分化和有毒的言论在政治阶层的同一而不是对立的族群之间占据主导地位,特别是在左翼;然而,这主要说明了政治集团之间的集体目标。