Persistence of brainstorming groups: How do people know when to stop?

Two experiments compared task persistence and productivity for brainstorming individuals and groups of various sizes under conditions without a time limit. We expected that the stop rules people employ in deciding to end a session would have important consequences for the relation between group size, persistence, and productivity. In Experiment I, conducted with individuals, dyads, and four- and six-person groups, it was found that persistence increased linearly with group size. As a result, the productivity loss usual in brainstorming groups was substantially reduced. This finding was replicated in Experiment 2, but only under conditions without time pressure. The degree to which a brainstorming topic was perceived as enjoyable did not affect persistence. Findings were consistent with the hypothesis that people stop neither when they are satisfied with their performance nor when they no longer enjoy the task, but when the expected relation between effort and performance falls below a certain cut-off point. The theoretical and practical implications of these findings are discussed. (C) 1999 Academic Press.