Research paper on users' active role in regulating reddit discourse?

A commenter on news.ycombinator linked an interesting paper looking at how users can shape the quality of a forum--it may have been a study about subreddits--and the authors observed that users, not moderators, can sometimes successfully help regulate their subreddit/forum through a tit-for-tat strategy: when new commenters show bad (undesirable w.r.t. to the subreddit's norms) behavior, users sometimes use hostility to keep things in check.

I'm probably distorting the summary somewhat, but I'm just curious to look at the paper again, but lost my bookmark. I got it from a comment on hacker news maybe up to 1 year ago.