Individual-Group Discontinuity in Group-Individual Interactions: Does Size Matter?

The consistent finding that interactions involving groups are more competitive than interactions between individuals is known as the discontinuity effect. We investigated the effects of group size in order to determine whether the effect is a true discontinuity or a continuous function of group size. We also asked whether dyads behave like larger groups. Four hundred and eighty seven students volunteered for the experiment. Individuals played 10 trials of two-choice prisoner's dilemmas against other individuals or against groups of sizes two through eight. Major findings included (a) individual-individual interactions were more cooperative than individual-group interactions, but there were no differences among group sizes; (b) dyads were indistinguishable from larger groups; and (c) data on expectations revealed that, before interacting, groups were not only distrusted by individuals but also distrusted the individuals. The discontinuity between individuals and groups-including dyads-appears to be a true discontinuity.