The Generality of the Individual-Group Discontinuity Effect: Variations in Positivity-Negativity of Outcomes, Players' Relative Power, and Magnitude of Outcomes

In a series of previous studies the authors have shown that intergroup interactions are dramatically more competitive and less cooperative than individual interactions. This phenomenon has been termed a discontinuity effect. The basic paradigm in this research measures competition and cooperation by choices made in a prisoner's dilemma game (PDG). Although a discontinuity effect has been observed in six separate studies, these have typically used a standard format. The present three studies extend the reliability and generality of the discontinuity effect by varying, respectively, the positivity-negativity of the outcomes in the PDG matrix, the power position of the players, and the magnitude of the PDG payoff values. In each of the three studies a statistically significant discontinuity effect was observed. The meaning of these studies is discussed, along with an unexpected interaction effect among gender, matrix type, and item sequence in the second study.