….The theory of cognitive dissonance—the extreme discomfort of simultaneously holding two thoughts that are in conflict—was developed by the social psychologist Leon Festinger in the 1950s. In a famous study, Festinger and his colleagues embedded themselves with a doomsday prophet named Dorothy Martin and her cult of followers who believed that spacemen called the Guardians were coming to collect them in flying saucers, to save them from a coming flood. Needless to say, no spacemen (and no flood) ever came, but Martin just kept revising her predictions. Sure, the spacemen didn’t show up today, but they were sure to come tomorrow, and so on. The researchers watched with fascination as the believers kept on believing, despite all the evidence that they were wrong.
“A man with a conviction is a hard man to change,” Festinger, Henry Riecken, and Stanley Schacter wrote in When Prophecy Fails, their 1957 book about this study. “Tell him you disagree and he turns away. Show him facts or figures and he questions your sources. Appeal to logic and he fails to see your point … Suppose that he is presented with evidence, unequivocal and undeniable evidence, that his belief is wrong: what will happen? The individual will frequently emerge, not only unshaken, but even more convinced of the truth of his beliefs than ever before.”
More here – The Atlantic