The real danger of the Sleeper Effect is that information from negative and unreliable sources is retained just as well as reliable ones. Once the source is forgotten, the information no longer seems unreliable or dubious.
Thus, when lies are told in propaganda, the liar only needs to wait for the people to believe. Once they have forgotten who said it, when and why they no longer have a reason not to believe.
Notes on the Heading:
In chapter 10, I discussed truth in repetition. This is one of the components of that concept that was heavily used by Hitler and Goebbels.
I remember this happening to myself in college. If an idea was discussed in class, there were times during the test when I couldn’t remember if it was a student who was wrong that said something, or the teacher correcting them. I knew the idea came from the discussion but was unable to remember the speaker. By the end of my colligate studies I wanted to plug my ears anytime, somebody said something incorrect for fear I would forget the source and then recall the wrong information on the test.
This is of even greater importance when dealing with media correction. They bury those corrections in fine print and back pages. The erroneous headline is still blazoned on our memories, pumped up by multiple newspapers, reports, and anchors discussing it, but the truth, the correction is mentioned briefly and quickly. Undoubtedly there are organizations who use this tactic intentionally. Some for ratings and circulation, some for influence and the spread of ideology.
from: The Sky Fall Conspiracy
Something in the way the human mind is created, the way its memory keeps and discards information, we can remember content, but rarely sources. This creates the “I’ve heard that before” moment for many people.
Kelman and Hovland did the initial studies where participants were given information from several different sources and brought them back over a series of weeks to see what they remembered. Content memory remained high, but the source of that memory degraded quickly.