Group Composition and Decision Making: How Member Familiarity and Information Distribution Affect Process and Performance

Abstract This study examines the role of group composition and information distribution on group process and decision making. Three-person groups performed a decision task that involved solving a murder mystery (Stasser & Stewart, 1992). Groups were composed of (a) three individuals familiar to each other, (b) two familiar individuals and a stranger, or (c) three strangers. Prior to group discussion, evidence bearing on the case was either fully shared (all members possessed identical information) or partially shared (each member possessed several unique clues to which no other member had access). The results indicate that all-stranger groups were most likely to identify the correct suspect when information was fully shared, however, all-familiar and 2 familiar/1 stranger groups were most likely to identify the correct suspect when critical clues remained unshared. Group process analysis reveals that this pattern of results was due to an “aggregation strategy” on the part of strangers and an “information pooling strategy” on the part of groups composed of familiar individuals.