A cognition, for the purpose of this theory, may be thought of as a piece of knowledge. The knowledge may be about an attitude, an emotion, a behavior, a value, and so on. People hold a multitude of cognitions simultaneously, and these cognitions form irrelevant, consonant or dissonant relationships with one another. Cognitive Irrelevance probably describes the bulk of the relationships among a person s cognitions.
Irrelevance simply means that the two cognitions have nothing to do with each other.
Two cognitions are consonant if one cognition follows from, or fits with, the other. People like consonance among their cognitions. We do not know whether this stems from the nature of the human organism or whether it is learned during the process of socialization, but people appear to prefer cognitions that fit together to those that do not. It is this simple observation that gives the theory of cognitive dissonance its interesting form. Two cognitions are said to be dissonant if one cognition follows from the opposite of another.