Sanders Writes a Chapter in the Behavioral Science Textbook

Bernie Sanders won't be the Democratic presidential nominee, yet so far he refuses to concede to Hillary Clinton, pledging to "continue to fight for every vote and every delegate we can get.” This is more than just stubbornness: Even if he bows out soon, Sanders and his supporters appear to believe more strongly than ever that the system is rigged against him and that Clinton is a captive of the banks -- and that Democratic voters have been rising up in support of his “political revolution, ” regardless of the actual vote count.

What happened? The Sanders campaign has become a classic example of the phenomenon of “group polarization,” arguably more so than any campaign in recent memory -- even Donald Trump's, which has greatly benefited from the same phenomenon.