Article Abstract
Franz, T. M., & Larson, J. R., Jr.  (2002).  The Impact of Experts on Information Sharing During Group Discussion.  Small Group Research, 33, 383-411.

Abstract.   Experts were predicted to impact information sharing during discussion in two ways.  First, expert members were expected to contribute more information themselves during discussion; and second, they were expected to cause nonexpert members to contribute more.  Furthermore, it was predicted that both dentification of the expert and task type would accentuate these differences.  These predictions were tested in a study where one third of the groups had an identified expert, one third had an unidentified expert, and one third had no expert.  Half of the groups were asked to identify a correct answer, whereas the other half were asked to give their opinion.  Results provided support for experts' contributing more information to group discussion; however, no support was found for their increasing other members' contributions.  Both identification of expertise and task type accentuated information sharing by experts.  These results are discussed in terms of their implications for the role of experts in information sampling and decision-making groups.