Mob Psychology

NPR Day to Day interviews the writer of the book, The Wisdom of Crowds, discuss the unwisdom of Crowds. Traits of the crowd: anonymity, lower social penalty and personal responsibility, and self-feeding cascade allows a smaller group of hard-core unruly fans to get everybody to chant racist epitets they normally don't chant.

Okay. You say, I heard it all before. However, conversely, if there's enough people who are known to never participate in violence with the crowd (like women and children), the crowd's behavior will be moderated. [Skip to 3:00 for that part]. link