Henry W. Riecken no relation cognitive dissonance
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.Initial study
Disconfirmed expectancy was famously illustrated in the 1956 book When Prophecy Fails by Leon Festinger, Henry W. Riecken, and Stanley Schachter.  The book gave an inside account of a doomsday cult led by Dorothy Martin (given the alias "Marion Keech" to preserve her privacy), of Chicago.  Martin claimed to have received messages from aliens forecasting a flood that would end the world on December 21, 1954.  Festinger and his researchers took the chance to pretend to be a part of the cult in order to observe its behaviors and reaction when the flood failed to occur.  Furthermore, Festinger's theory of cognitive dissonance, which would be published the following year, predicted that the failure of the prophecy would not break the cult.  Instead the group members would look for ways to justify their actions and maintain confidence in the cult.Some members abandoned the group when the prophecy failed to be fulfilled, but most stayed.  Those who stayed did not have weakened resolve. There was in fact an increase in their proselytization and their fervor for the new religion. The prediction of the Earth's destruction became a disconfirmed expectancy which resulted in the dissonant cognitions "the world is going to end" and "the world did not end".  Those who left the cult accepted that they were wrong and discarded their false cognition.  Those who stayed instead looked for ways to explain the event in a way that would maintain their beliefs.  Eventually they came to the agreement that the planet was spared because of their prayers and actions.  Festinger et al. theorized that five conditions must be present for this to occur; that is, there are five conditions that must be met such that a disconfirmation can lead to increased strength of belief: strong belief, commitment to the belief, the possibility that the belief is false, recognition of the disconfirmation, and strong social support (these are detailed below).Uses as a methodology
As noted above, disconfirmed expectancy is often paired with cognitive dissonance because the disconfirmation results in two competing cognitions within the individual.  As such, disconfirmed expectancy is often used as a reliable method for inducing cognitive dissonance in experimental designs. Generally this is done by introducing an outcome which is dissonant with the participant's established self-concept. The self-concept is often induced as well by creating a strong expectancy toward a certain outcome.  For example, in Carlsmith and Aronson (1963) participants were led to believe that a set of signals would reliably precede certain outcomes.  To create the disconfirmation, after a few trials the experimenters paired a new outcome with a previous stimulus.
When this is not possible, participants are sorted into groups or placed onto a graded scale according to their prior beliefs.  Experimenters can do this as Festinger and his researchers did, i.e. join a cult and observe the impending disconfirmation, though this can also be achieved by pre-testing participants and grouping them based on their responses. These methods—covert/participant observation, pre-selection—are not ideal because they pose the problem of selection bias due to non-random assignment.
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