Disconfirmed expectancy is a psychological term for what is commonly known as a failed prophecy. According to the American social psychologist Leon Festinger's theory of cognitive dissonance, disconfirmed expectancies create a state of psychological discomfort because the outcome contradicts expectancy. Upon recognizing the falsification of an expected event an individual will experience the competing cognitions, "I believe [X]," and, "I observed [Y]." The individual must either discard the now disconfirmed belief or justify why it has not actually been disconfirmed. As such, disconfirmed expectancy and the factors surrounding the individual's consequent actions have been studied in various settings.
Thank you for this (VERY) useful post. :-)