MULTIPARTY NEGOTIATION SUPPORT 129 Journal of Management Information Systems / Summer 2002, Vol. 19, No. 1, pp. 129–150. © 2002 M.E. Sharpe, Inc. 0742–1222 / 2002 $9.50 + 0.00. Multiparty Negotiation Support: The Role of Visualization’s Influence on the Development of Shared Mental Models RODERICK I. SWAAB, TOM POSTMES, PETER NEIJENS, MARIUS H. KIERS, AND ADRIE C.M. DUMAY RODERICK I. SWAAB is a doctoral candidate at the Amsterdam School of Communica- tions Research. He received his master’s degree in communication and organizations at the University of Amsterdam. His research focuses on the role of information and communication in negotiation processes. TOM POSTMES is a senior lecturer at the School of Psychology, University of Exeter. He holds a doctorate in social psychology from the University of Amsterdam. He is affiliated with the Department of Communication Science, University of Amsterdam, and holds a fellowship of the Royal Netherlands Academy of Arts and Sciences (KNAW). He is currently an Associate Editor of the British Journal of Social Psy- chology. His research and teaching is concerned with computer-mediated communi- cation, social influence in groups, and collective behavior. PETER NEIJENS is a senior professor in communications at the University of Amsterdam and scientific director of the Amsterdam School of Communications Research. He holds a doctorate in methodology and statistics from the University of Amsterdam. His research focuses on corporate communication, decision-making, communication campaigns and media effects, and public opinion. MARIUS H. KIERS is a senior consultant at TNO building and construction research. He earned his master’s degree in economics at the Free University Amsterdam. He specializes in innovation and technology management, as well as in spatial econom- ics and regional development. ADRIE C.M. DUMAY is the head of medical informatics of TNO Prevention and Health. He holds a doctorate in information and communication theory from Delft Univer- sity of Technology. The research was carried out while he was head of the Virtuality Lab of TNO. His present work focuses on simulation and information systems in medicine. ABSTRACT: The study examines a method for supporting multiparty negotiations by means of a Negotiation Support System (NSS). More specifically, this study investi- gated the effect of visualization support on the development of shared mental models among negotiators who resolved a spatial planning dispute. The objective of this study is to determine how to support the development of shared mental models in order to stimulate more productive negotiations. A further goal is to provide guidelines for the design of NSS. Compared with a control condition, visualization improved three