What is the Prisoner’s Dilemma?

Here’s a description from w9a

In game theory, the prisoner’s dilemma is a type of non-zero-sum game in which two players can “cooperate” with or “betray” the other player. In this game, as in all game theory, the only concern of each individual player (“prisoner”) is maximizing their own payoff, without any concern for the other player’s payoff per se. In the classic form of this game, Cooperating is strictly dominated by defecting (i.e., betraying one’s partner), so that the only possible equilibrium for the game is for all players to defect. In simpler terms, no matter what the other player does, one player will always gain a greater payoff by playing defect. Since in any situation playing defect is more beneficial than cooperating, all rational players will play defect.

How does it apply to Digg?

I have long thought about a way to game digg wherein minority voting blocs would approximate the appearance of majority appeal for stories. This tactic though has and is in play currently on digg, with voting blocs ranging from rivals at AOL to Republican / Libertarian online campaigners.

Recently though I took notice of another phenomena that seems to occurs on digg. The tactic is a tit-for-tat strategy for gaining digg front-page promotions.

The way tit-for-tat works in the classic Prisoner’s Dilemna scenario is that even though in one game of prisoner, it would make sense to defect; in an unknown number of games, it’s better to cooperate with other people by trusting them at first and then ceasing to trust them if they betray the trust until they start cooperating again. The tit for tat strategy works so well, all things being equal, it’s never been beaten in computerized simulations of various tactics.

On digg it works through the friends system. The game is that friends are assumed to trust you by digging your stories. You can trust them back by digging their stories. I noticed recently that when I submit stories, some people who have befriended me always digg them. I didn’t even really notice that I had so many friends until I noticed this tab with my 39 friends, most of whom I don’t know at all. The word friends is kind of confusing, because my real friends are all lurkers and don’t bother interacting with digg, or don’t have the time to read digg regularly enough for the friends feature to be interesting, (aside from Kevin Rose for obvious reasons).

Thus friends seem to really be tit-for-tat partners, waiting for you to engage and become their ally in the quest to get digg submissions. A good way to spot a tit-for-tat player is to look for a digg user with a large number of one sided friendships where they are friends with many people and not many return the favor, such as my new tit-for-tat friend chrisek with 253 friends and 75 reciprocating.

I like this theory because it seems that as digg expands, the ecosystem surrounding it must constantly evolve to adapt, and this is an interesting way it is evolving.

Revised tit for tat strategy description to be more accurate.