Cognitive dissonance, according to Festinger ( 1957), is a psychological tension having motivational characteristics. The theory of cognitive dissonance concerns itself with the conditions that arouse dissonance in an individual and with the ways in which dissonance can be reduced.
The units of the theory are cognitive elements and the relationships between them. Cognitive elements or cognitions are "knowledges" or items of information, and they may pertain to oneself or to one's environment. Knowledge of one's feelings, behavior, and opinions as well as knowledge about the location of goal objects, how to get to them, what other people believe, and so forth, are examples of cognitive elements.
The relation that exists between two elements is consonant if one implies the other in some psychological sense. Psychological implication may arise from cultural mores, pressure to be logical, behavioral commitment, past experience, and so on. What is meant by implication is that having a given cognition, A, leads to having another given cognition, B. The detection of psychological implication is frequently possible by measurement of what else a person expects when he holds a given cognition.