The purposes of this study were: (1) to test several social decision schemes to obtain plausible explanations of different group processes in solving different disjunctive tasks; and (2) to study both dyads and tetrads solving a eureka and a non-eureka disjunctive task. Social decision schemes theory assumes that a group decision is a joint function of the distribution of individual member preferences and the scheme that operates on this distribution. This study assumed that there is one distribution for solving a eureka disjunctive task and another for solving a non-eureka disjunctive task. Swedish fourth and fifth grade students were randomly assigned to different group sizes (one, two, or four). Thirty-two replications were performed for every experimental condition. The results indicated that different processes are created by different tasks. (Author/BW)