In their fantastic book about cognitive dissonance, Mistakes Were Made (But Not by Me), Carol Tavris and Elliot Aronson write about the great psychologist Leon Festinger who, in 1957, infiltrated a doomsday cult. The cult was led by Dorothy Martin who called herself Sister Thedra. She convinced her followers in Chicago an alien spacecraft would suck them up and fly away right as a massive flood ended the human race on December 21, 1954. Many of her followers gave away everything they owned, including their homes, as the day approached. Festinger wanted to see what would happen when the spaceship and the flood failed to appear. Festinger hypothesized the cult members faced the choice of either seeing themselves as foolish rubes or assuming their faith had spared them. Would the cult members keep their weird beliefs beyond the date the world was supposed to end and become even more passionate as had so many groups before them under similar circumstances? Of course they did. Once enough time had passed they could be pretty sure no spaceships were coming, they began to contact the media with the good news: their positive energy had convinced God to spare the Earth. They had freaked out and then found a way to calm down. Festinger saw their heightened state of arousal as a special form of anxiety – cognitive dissonance. When you experience this arousal it is as if two competing beliefs are struggling in a mental bar fight, knocking over chairs and smashing bottles over each other’s heads. It feels awful, and the feeling persists until one belief knocks the other out cold.
Here is a link to the entire article if you're interested.