Social psychologists have long known that human beings often make choices about what to think, and what to do, based on the thoughts and actions of others. Simply stated: We like to follow the crowd. As a psychological phenomenon, it's called "social proof." And according to Robert Cialdini, the Regents' Professor of Psychology and Marketing at Arizona State University and Distinguished Professor of Marketing in the W. P. Carey School, "social proof" is one of the six key principles underlying the powerful science of persuasion.<br><br><a href='http://knowledge.wpcarey.asu.edu/index.cfm?fa=viewArticle&id=1347' target='_blank'>http://knowledge.wpcarey.asu.edu/index.cfm?fa=viewArticle&id=1347</a><br><br>