Voluntary participation and cooperation in a collective-good game

We study the effect of voluntary participation in the context of a collective-good experiment. We investigate whether the freedom to participate in the game or not can affect contribution levels over time. The analysis of two voluntary-participation treatments supports a noticeable effect of an attractive exit option on contribution levels. We conclude that voluntary participation can induce a recovery of cooperation levels when the payoff yielded by the exit option is high enough, so that the usually observed decay of average contribution levels can be counteracted.