Cooperation Theory and Anonymous Trolling
I am reading Robert Axelrod's the Evolution of Cooperation after seeing its work on The Prisoner's Dilemma turn up over and over in Garett Jones' Hive Mind: How Your Nation's IQ Matters Much More Than You Think.
There is considerable research (indeed, a whole book's worth) of material here dealing with cooperation and the Dilemma with a final analysis that continual cooperation is good in the long run and that if one person reneges on their dealings, the other party ought to punish them twice (or, the offender must show humility and trust twice to the offendee) in order for things to get back to normal.
Applying this to online spaces, I find this strategy only works if both parties are identitifed. In anonymous spaces, reneging once on a deal means instantly breaking all trust now and forever with the other party with no way to really get it back.
Yet, Cooperation online can still be mutually beneficial. I don't believe that this has been properly studied, but actions such as answering questions or seeding torrents demonstrates that there must be a personal benefit when none exist prima facie.