Cognitive Dissonance, a definition

This is what triggered the toxic exchanges that have riveted the exer audience for days now. I was curious to what it meant so I dug up a working definition. I thought it's very interesting that the theory was developed from studying a cult and I see similar patterns here in this exer community.

Cognitive dissonance is a psychological phenomenon that refers to the discomfort felt at a discrepancy between what you already know or believe, and new information or interpretation. It therefore occurs when there is a need to accommodate new ideas, and it may be necessary for it to develop so that we become "open" to them. Dissonance can go "over the top", leading to two interesting side-effects for learning:
*if someone is called upon to learn something which contradicts what they already think they know — particularly if they are committed to that prior knowledge — they are likely to resist the new learning.
*if learning something has been difficult, uncomfortable, or even humiliating enough, people are not likely to admit that the content of what has been learned is not valuable. To do so would be to admit that one has been "had", or "conned".

Cognitive dissonance was first investigated by Leon Festinger and associates, arising out of a participant observation study of a cult which believed that the earth was going to be destroyed by a flood, and what happened to its members — particularly the really committed ones who had given up their homes and jobs to work for the cult — when the flood did not happen. While fringe members were more inclined to recognise that they had made fools of themselves and to "put it down to experience", committed members were more likely to re-interpret the evidence to show that they were right all along (the earth was not destroyed because of the faithfulness of the cult members).

Sounds all too familiar doesn’t it? Verrrrry interesting.