Fringe communities promoting conspiracy theories and extremist ideologies
have thrived on mainstream platforms, raising questions about the mechanisms
driving their growth. Here, we hypothesize and study a possible mechanism: new
members may be recruited through fringe-interactions: the exchange of comments
between members and non-members of fringe communities. We apply text-based
causal inference techniques to study the impact of fringe-interactions on the
growth of three prominent fringe communities on Reddit: r/Incel,
r/GenderCritical, and r/The_Donald. Our results indicate that
fringe-interactions attract new members to fringe communities. Users who
receive these interactions are up to 4.2 percentage points (pp) more likely to
join fringe communities than similar, matched users who do not.
This effect is influenced by 1) the characteristics of communities where the
interaction happens (e.g., left vs. right-leaning communities) and 2) the
language used in the interactions. Interactions using toxic language have a 5pp
higher chance of attracting newcomers to fringe communities than non-toxic
interactions. We find no effect when repeating this analysis by replacing
fringe (r/Incel, r/GenderCritical, and r/The_Donald) with non-fringe
communities (r/climatechange, r/NBA, r/leagueoflegends), suggesting this growth
mechanism is specific to fringe communities. Overall, our findings suggest that
curtailing fringe-interactions may reduce the growth of fringe communities on
mainstream platforms.

边缘社区通过交换评论吸引新成员是推动边缘社区增长的机制之一。当有毒语言被使用时，这种相互作用会对边缘社区的吸引新成员的能力产生更大的影响。总体而言，阻止边缘相互作用可能会减少主流平台上边缘社区的增长。

陌生人危险！与边缘用户的跨社区互动增加了 Reddit 上边缘社区的增长

Stranger Danger! Cross-Community Interactions with Fringe Users Increase  the Growth of Fringe Communities on Reddit

Over the past few years, a number of new "fringe" communities, like 4chan or
certain subreddits, have gained traction on the Web at a rapid pace. However,
more often than not, little is known about how they evolve or what kind of
activities they attract, despite recent research has shown that they influence
how false information reaches mainstream communities. This motivates the need
to monitor these communities and analyze their impact on the Web's information
ecosystem. In August 2016, a new social network called Gab was created as an
alternative to Twitter. It positions itself as putting "people and free speech
first'", welcoming users banned or suspended from other social networks. In
this paper, we provide, to the best of our knowledge, the first
characterization of Gab. We collect and analyze 22M posts produced by 336K
users between August 2016 and January 2018, finding that Gab is predominantly
used for the dissemination and discussion of news and world events, and that it
attracts alt-right users, conspiracy theorists, and other trolls. We also
measure the prevalence of hate speech on the platform, finding it to be much
higher than Twitter, but lower than 4chan's Politically Incorrect board.

本文收集和分析了 22M 的数据，探讨了一个新社交媒体 Gab 的使用，发现其主要被用于传播和讨论新闻和世界事件，并吸引了极右翼用户，阴谋论者和其他喷子。同时，本文还测量了平台上仇恨言论的流行程度，发现其比 Twitter 高但低于 4chan 的 Politically Incorrect 讨论版。

Gab 是什么？言论自由的屏障还是极右反响室？

What is Gab? A Bastion of Free Speech or an Alt-Right Echo Chamber?

As the number and the diversity of news outlets on the Web grow, so does the
opportunity for "alternative" sources of information to emerge. Using large
social networks like Twitter and Facebook, misleading, false, or agenda-driven
information can quickly and seamlessly spread online, deceiving people or
influencing their opinions. Also, the increased engagement of tightly knit
communities, such as Reddit and 4chan, further compounds the problem, as their
users initiate and propagate alternative information, not only within their own
communities, but also to different ones as well as various social media. In
fact, these platforms have become an important piece of the modern information
ecosystem, which, thus far, has not been studied as a whole.
In this paper, we begin to fill this gap by studying mainstream and
alternative news shared on Twitter, Reddit, and 4chan. By analyzing millions of
posts around several axes, we measure how mainstream and alternative news flows
between these platforms. Our results indicate that alt-right communities within
4chan and Reddit can have a surprising level of influence on Twitter, providing
evidence that "fringe" communities often succeed in spreading alternative news
to mainstream social networks and the greater Web.

本文旨在填补目前尚未系统研究的现代信息生态系统的研究空缺，研究了 Twitter、Reddit 和 4chan 上分享的主流和另类新闻，并发现在 4chan 和 Reddit 上的 “边缘” 社区通常能够成功地在主流社交网络和更广泛的网站上传播另类信息，并提供证据显示这些社区对 Twitter 上有相当程度的影响力。