Sleeper Effect : "hidden" effect of a propaganda message even when it comes from a discredible source. After enough time people forget the source and only remember the message.
Exposure Effect: people express undue liking for things merely because they are familiar with them.
Protectection Motivation Theory : How fear appeals?
Law of Primacy: side of an issue presented first will have greater effectiveness than the side presented subsequently
Cognitive dissonance theory: there is a tendency for individuals to seek consistency among their cognitions (i.e., beliefs, opinions). When there is an inconsistency between attitudes or behaviors (dissonance), something must change to eliminate the dissonance. In the case of a discrepancy between attitudes and behavior, it is most likely that the attitude will change to accommodate the behavior.
Consider someone who buys an expensive car but discovers that it is not comfortable on long drives. Dissonance exists between their beliefs that they have bought a good car and that a good car should be comfortable. Dissonance could be eliminated by deciding that it does not matter since the car is mainly used for short trips (reducing the importance of the dissonant belief) or focusing on the cars strengths such as safety, appearance, handling (thereby adding more consonant beliefs). The dissonance could also be eliminated by getting rid of the car, but this behavior is a lot harder to achieve than changing beliefs.
Law of Recency