  Online social media platforms use automated moderation systems to remove or
reduce the visibility of rule-breaking content. While previous work has
documented the importance of manual content moderation, the effects of
automated content moderation remain largely unknown. Here, in a large study of
Facebook comments (n=412M), we used a fuzzy regression discontinuity design to
measure the impact of automated content moderation on subsequent rule-breaking
behavior (number of comments hidden/deleted) and engagement (number of
additional comments posted). We found that comment deletion decreased
subsequent rule-breaking behavior in shorter threads (20 or fewer comments),
even among other participants, suggesting that the intervention prevented
conversations from derailing. Further, the effect of deletion on the affected
user's subsequent rule-breaking behavior was longer-lived than its effect on
reducing commenting in general, suggesting that users were deterred from
rule-breaking but not from commenting. In contrast, hiding (rather than
deleting) content had small and statistically insignificant effects. Our
results suggest that automated content moderation increases adherence to
community guidelines.
