Sleeper Effect

The Sleeper Effect is a psychological phenomenon in which an idea or message has a delayed persuasive effect and becomes more effective as time goes on. Typically, the impact of a message usually decrease over time but in instances where the message came from a source with low credibility the persuasive impact can actually increase after time has passed. It is theorized this occurs when the source of low credibility is not longer mentally associated with the message because time has weakened the association between the message and the untrustworthy source. Therefore the message becomes more credible because it is not associated with the source.