If decision-relevant information is distributed among team members, the group is inclined to focus on shared information and to neglect unshared information, resulting often in suboptimal decisions. This classical finding is robust in experimental settings, in which the distribution of information is created artificially by an experimenter. The current paper looks at information sharing effects when access to information is not restricted, and decision makers are very familiar with the decision task. We analyzed archival search and discussion data obtained from business executives completing a personnel selection exercise. Information popularity in the population from which groups were composed predicted number of group members accessing items during information searches and whether the group discussed the items. The number of group members who accessed an item predicted whether information was repeated during discussion, and repetition predicted which items were included on an executive summary. Moreover, cognitively central group members were more influential than cognitively peripheral members. One implication is that collective decision making amplifies what is commonly known at the expense of disseminating what is not
