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

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 than non-toxic ones. We find no such effect when repeating the analysis with non-fringe communities. Overall, our findings suggest that curtailing fringe interactions may reduce the growth of fringe communities on mainstream platforms.

In Proceedings of the International AAAI Conference on Web and Social Media, Volume 18