THE COMMON KNOWLEDGE EFFECT - INFORMATION SHARING AND GROUP JUDGMENT

The hypothesis that the influence of an item of information on a group judgment is directly related to the number of group members who hold that information before group discussion was tested. Three-member groups read short descriptions of students and were asked to make individual and then group consensus judgments about those students' grades in the course. Information held by all members before group discussion had more influence on the group judgments than information held by only 1 member. However, no effect of information distribution was found when controlling for member judgments, suggesting that the impact of the information, and hence the effects of distribution across members, was mediated by its impact on individual-member prediscussion judgments. The group judgments were no more accurate than the average of the member judgments. Group members were not aware of the common knowledge effect's influence on their use of information.