Effects of Group Size Uncertainty and Protocol of Play in a Common Pool Resource Dilemma

Abstract

This study investigated the effect of group size uncertainty in a single-stage step-level common pool resource dilemma under a sequential (SEQ) and a Self-paced Sequential (SPS) protocol of play. In the uncertain group size condition, participants were told that their group was equally likely to be any size between three and seven persons. In the certain group size condition, the group size was always five. In the SEQ protocol, decisions were made in a pre-specified order such that each player knew his or her position in the sequence, as well as the combined requests of all the preceding players in the sequence. In the SPS protocol, participants could choose when to make their decisions. In both protocols, we replicated the position effects—individual requests are inversely related to the players' positions in the sequence with the first mover requesting most, and the last mover requesting the least. We also found that the position effect was stronger in SEQ than in SPS, and when group size was certain than when it was not. Relative to group size certainty, group size uncertainty decreased total requests and increased provision rates.