Sleeper Effect


The Sleeper Effect is a psychological phenomenon that occurs when the persuasive impact of a message or information increases over time, despite the initial discounting of the message due to its association with a low-credibility source. The term was first introduced by Carl Hovland, a social psychologist who conducted extensive research on persuasion and attitude change in the 1940s and 1950s.


The Sleeper Effect is based on the idea that people tend to remember the content of a message but gradually forget the source, especially when the source is initially perceived as lacking credibility or trustworthiness. As time passes and the source's influence diminishes, the message becomes more persuasive because people focus more on the content of the message and less on the source.

Several factors contribute to the Sleeper Effect:

  • Source Amnesia: This is the primary factor responsible for the Sleeper Effect. Source amnesia refers to the tendency of people to forget the origin of information while retaining the information itself. As the memory of the source fades, the information may become more persuasive.
  • Cognitive Dissonance: Cognitive dissonance is the psychological discomfort experienced when an individual holds two or more conflicting beliefs, values, or attitudes. When people encounter a persuasive message from a low-credibility source, they may initially discount the message to reduce cognitive dissonance. However, as the memory of the source fades, the persuasive impact of the message may increase.
  • Reevaluation of the Source: Over time, people might reevaluate their initial perception of the source's credibility, especially if new information or experiences contradict their initial judgment. This reevaluation may lead to an increased persuasive impact of the message.


The Sleeper Effect has important implications for various fields, such as advertising, marketing, and political communication. Understanding this phenomenon can help professionals craft more effective messages and strategies that take advantage of the Sleeper Effect to enhance persuasion.

For example, advertisers might choose to present their messages using sources initially perceived as low-credibility, knowing that the persuasive impact of the message will increase over time. Similarly, political campaigns may strategically use negative information from low-credibility sources to attack their opponents, anticipating that the negative impact will grow as the source's influence fades.

However, it is crucial to consider the ethical implications of using the Sleeper Effect in persuasive communication, as exploiting this phenomenon may involve deception and manipulation of audiences.

In summary, the Sleeper Effect is a psychological phenomenon where the persuasive impact of a message increases over time, despite its initial discounting due to a low-credibility source. Understanding this effect can be beneficial for crafting persuasive messages in various fields, but it is essential to consider the ethical implications of using this phenomenon to influence audiences.

See Also

Information Analysis