Cheap Pseudonyms Harm Community and Cooperation

By Peter Rothman, published at 10 May 2007 - 8:12pm, last updated 11 years 6 days ago.

In a recently published paper, "The Evolution of Cooperation under Cheap Pseudonyms", Feldman and Chuang of the UC Berkeley P2Pecon group describe their analysis of the impact of cheap and available pseudonyms on the evolution of cooperation. Specifically, they analyze the behavior of the well known tit-for-tat (TFT) and probablistic tit-for-tat (PTFT) strategies in evolutionary game theory when players have access to "cheap" pseudonyms.

This research is relevant to developers of social networking and community software with weak or non-existent identity management features because they are susceptible to "the whitewashing attack, where users continuously discard their old identity and acquire a new one to escape the consequences of their bad behavior."

Their analysis shows that both TFT and PTFT are unstable against whitewashing attacks unless the costs of obtaining a new identity are very high. Furthermore, they conclude that "discriminators can defeat whitewashers only if the probability to cooperate with strangers is small enough, which in turn degrades social welfare." That is, in order to keep from being cheated, users have to restrict the group they cooperate with to known trusted friends and eliminate or at least limit their interactions with strangers. The result is an unstable community with limited growth potential.