What one may say on the internet is increasingly controlled by a mix of automated programs, and decisions made by paid and volunteer human moderators. On the popular social media site Reddit, moderators heavily rely on a configurable, automated program called "Automoderator" (or "Automod"). How do moderators use Automod? What advantages and challenges does the use of Automod present? We participated as Reddit moderators for over a year, and conducted interviews with 16 moderators to understand the use of Automod in the context of the sociotechnical system of Reddit. Our findings suggest a need for audit tools to help tune the performance of automated mechanisms, a repository for sharing tools, and improving the division of labor between human and machine decision making. We offer insights that are relevant to multiple stakeholders-creators of platforms, designers of automated regulation systems, scholars of platform governance, and content moderators.

Online harassment is a complex and growing problem. On Twitter, one mechanism people use to avoid harassment is the blocklist , a list of accounts that are preemptively blocked from interacting with a subscriber. In this article, we present a rich description of Twitter blocklists – why they are needed, how they work, and their strengths and weaknesses in practice. Next, we use blocklists to interrogate online harassment – the forms it takes, as well as tactics used by harassers. Specifically, we interviewed both people who use blocklists to protect themselves, and people who are blocked by blocklists. We find that users are not adequately protected from harassment, and at the same time, many people feel that they are blocked unnecessarily and unfairly. Moreover, we find that not all users agree on what constitutes harassment. Based on our findings, we propose design interventions for social network sites with the aim of protecting people from harassment, while preserving freedom of speech.

When toxic online communities on mainstream platforms face moderation measures, such as bans, they may migrate to other platforms with laxer policies or set up their own dedicated websites. Previous work suggests that within mainstream platforms, community-level moderation is effective in mitigating the harm caused by the moderated communities. It is, however, unclear whether these results also hold when considering the broader Web ecosystem. Do toxic communities continue to grow in terms of their user base and activity on the new platforms? Do their members become more toxic and ideologically radicalized? In this paper, we report the results of a large-scale observational study of how problematic online communities progress following community-level moderation measures. We analyze data from r/The_Donald and r/Incels, two communities that were banned from Reddit and subsequently migrated to their own standalone websites. Our results suggest that, in both cases, moderation measures significantly decreased posting activity on the new platform, reducing the number of posts, active users, and newcomers. In spite of that, users in one of the studied communities (r/The_Donald) showed increases in signals associated with toxicity and radicalization, which justifies concerns that the reduction in activity may come at the expense of a more toxic and radical community. Overall, our results paint a nuanced portrait of the consequences of community-level moderation and can inform their design and deployment.

Deplatforming refers to the permanent ban of controversial public figures with large followings on social media sites. In recent years, platforms like Facebook, Twitter and YouTube have deplatformed many influencers to curb the spread of offensive speech. We present a case study of three high-profile influencers who were deplatformed on Twitter---Alex Jones, Milo Yiannopoulos, and Owen Benjamin. Working with over 49M tweets, we found that deplatforming significantly reduced the number of conversations about all three individuals on Twitter. Further, analyzing the Twitter-wide activity of these influencers' supporters, we show that the overall activity and toxicity levels of supporters declined after deplatforming. We contribute a methodological framework to systematically examine the effectiveness of moderation interventions and discuss broader implications of using deplatforming as a moderation strategy.

Should social media platforms intervene when communities repeatedly break rules? What actions can they consider? In light of this hotly debated issue, platforms have begun experimenting with softer alternatives to outright bans. We examine one such intervention called quarantining, that impedes direct access to and promotion of controversial communities. Specifically, we present two case studies of what happened when Reddit quarantined the influential communities r/TheRedPill (TRP) and r/The_Donald (TD). Working with over 85M Reddit posts, we apply causal inference methods to examine the quarantine's effects on TRP and TD. We find that the quarantine made it more difficult to recruit new members: new user influx to TRP and TD decreased by 79.5% and 58%, respectively. Despite quarantining, existing users' misogyny and racism levels remained unaffected. We conclude by reflecting on the effectiveness of this design friction in limiting the influence of toxic communities and discuss broader implications for content moderation.