Group Size and Others' Strategy in an N-Person Game

Abstract

The effects of group size and cooperativeness of others upon an individual's propensity to cooperate is studied using the Take-Some format of the Prisoner's Dilemma game. By holding utility effects constant, this format permits comparisons to be made between the performances of subjects in different size groups. A 2 × 2 experimental design was employed in which 48 male subjects were assigned to stooge-player groups comprised of either two or eleven “others.” Stooge players in these groups employed either high or low cooperative strategies in 200 repeated trials of play. The results show a significant group-size effect upon the degree of cooperativeness evidenced by the subjects. A significant group size x stooge strategy interaction was also observed, subjects in the 3-person group being responsive to the “others” while subjects in the larger group remained relatively unaffected by “others' ”cooperativeness. An interpretation of these results is made in terms of the “accountability” of an individual to others in the group.