Flexibility - the ability to react swiftly to others' choices - facilitates collusion by reducing gains from defection before opponents react. Under imperfect monitoring, however, flexibility may also hinder collusion by inducing punishment after too few noisy signals. The combination of these...

We study the effect of group size on cooperation in voluntary contribution mechanism games. As in previous experiments, we study four- and eight-person groups in high and low marginal per capita return (MPCR) conditions. We find a positive effect of group size in the low MPCR condition, as in...