Political Communication Vol. 25, Issue 4, Pages 345-365 October 2008 ÌÇÐÄvlog¹ÙÍø Authors See citation below for complete author information. Matthew Baum Marvin Kalb Professor of Global Communications Citation Baum, Matthew A., and Tim Groeling. "New Media and the Polarization of American Political Discourse." Political Communication 25.4 (October 2008): 345-365.