Contributor Dilemma in Structured Tri-game

Some people in the group whose we call contributors take on tasks and earn less than others earn. The existence of these contributors is more confusing than the free-riders phenomenon in traditional social dilemmas. This paper uses the Nash equilibrium to explain why contributors exist, and finds that the reason why contributors become contributors is that their own situation will not get better if the group does not undergo other changes. This cooperative dilemma to contributors is called the “Contributor Dilemma”, which is an individual dilemma rather than a group dilemma. In addition, the simulation results obtained by evolutionary game theory verify the conclusions based on the Nash equilibrium and reveal the impact of tasks' benefits and costs on the number of contributors. Punishment, as a representative of mechanisms for promoting cooperation, is used in simulation to test its effectiveness in the “Contributor Dilemma”.