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Sleeper Effect

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After World War 2, Yale University psychologists, Carl Hovland and Herbert Kelman developed a novel way to study persuasion. Instead of looking at the content of the messages being sent or the way that the audience perceived these messages, they examined how the perceived credibility of a source affects our information processing skills. They made some unexpected discoveries.

Hovland and Kelman found that audiences are forgetful. When exposed to new claims, audiences paid some attention to source credibility at first. However, over time, audiences remembered ideas and claims but forgot the names and qualifications of the sources that made these claims in the first place. This tendency to remember the content of an article while forgetting the identity and credibility of the source is known as “the sleeper effect.”

The sleeper effect is quite useful for propagandists who disseminate disinformation. When we initially encounter claims distributed by a dubious source, we are likely to reject those claims. However, as time goes on, we might remember and propagate this falsehood without recalling the questionable source. Luckily, Hovland and Kelman did discover that giving the audience a quick reminder of the source helped them to recall its credibility.

How can we combat the sleeper-effect? There are several steps we can take.

  • Every single time you repeat information, whether in person or in an online forum, you should always mention where you encountered this claim and explain who originally said it.
  • If you cannot remember the source of a claim, use a search engine to find out if others have said something similar. After all, if you know enough about a claim to share it with your friends, you should be able to turn it into a Google search query. Even if you don’t find the original source of the idea, you will be able to figure out whether or not credible individuals have advanced similar ideas.
  • Whenever a friend or family member repeats information face-to-face or online, you should always ask where it was originally published. It is possible to ask this question diplomatically without seeming annoying or confrontational.

Annoying approach: “Ebola in San Diego. Ludicrous. Give me a break. On what terrible, fake-news site did you find this nonsense?”

Diplomatic approach: “An ebola outbreak in San Diego sounds terrifying. I would love to find out more about this. Where was this published? Do you remember who said it?”