The Effect Of The Sleeper

The effect of the sleeper is a term that is used to refer to the influence of information that in principle had been discarded as impossible or very unlikely. In theory, this effect occurs when someone initially ignores a message, as it does not appear to be credible, and then, little by little, they begin to believe precisely this information that they had discarded. This change can be generated from external evidence in favor or by an internal thought cycle that motivates us to re-evaluate the information.

This strategy may seem a bit contradictory if we take into account that people tend to question messages more than we doubt at first. However, this does not mean that content stored in our memory, which was started without giving consideration, ends up being important. In fact, it will begin to be so as soon as we find a data or a suspicion that makes us change our strategy and start using the confirmation. 

The beginnings of the sleeper effect

In the 1940s, during the Second World War, a large number of advertising campaigns were developed aimed at fostering a positive spirit in everything concerning war. Specifically, the United States War Department wanted to know if its propaganda films were really effective.

To this end, a series of experiments were developed to analyze how soldiers’ attitudes were affected. The results were quite peculiar, since it was appreciated that these short films did not affect the attitudes of the soldiers as easily as it was thought. When the films were informative, they strengthened some existing attitudes, but generally the shorts did not foster optimism. The producers and psychologists did not reach the objective for which they made the short films.

Interestingly, what the researchers found was that the short films had a curious effect on the soldiers, after a few months. While their attitudes towards the war did not change immediately, nine weeks later some changes could be observed. For example, those soldiers who saw the movie The Battle of Britain  immediately showed a little sympathy for the British. Furthermore, nine weeks later, this sympathy had increased. Carl Hovland, a professor at Yale University, called this phenomenon “the sleeper effect.”

As expected, this phenomenon has been widely questioned in the area of ​​scientific psychology, since it cannot be stated with precision that the change in attitudes, after such a long period of time, is due solely to the vision of a short film. There are actually studies that show that the persuasive effect of a message is greater just after the information is received. Thus, as time passes, the influence would tend to decrease. This is known by advertisers, who offer us a better offer if we are quick to make the purchase.

Conditions for the sleeper effect to occur

For this curious phenomenon to occur, two essential conditions must be present:

• A strong initial impact: The sleeper effect only emerges if the persuasive message has a very strong initial impact. This is because this force is the guarantee so that it is stored in our memory and we can mentally work with it.
• A message for granted: when the source of the information is not reliable, we tend to discredit the message. However, if we discover that the source is not to be trusted only after we have seen the movie, then we will be more receptive to the message and more suggestible.

Advertisers in general know this detail very well, since they can write an article about the benefits of chocolate, convincing us to consume it. However, only at the bottom of the page do they indicate that the writer is a person involved in a chocolate manufacturing company. Thus, when we receive the persuasive message before knowing the source from which the information comes, we will be exposed to the effect of the sleeper.

The explanation for this phenomenon can be very simple, and it is that in our mind, after time, it forgets that the source was not totally reliable and only remains with the initial information. This is the reason why, over time, we are more suggestible to the message compared to what we were at first.

This is how the sleeper effect is produced, with which advertising and the media can persuade us to focus our attention, buy certain products, or make us vote for a certain candidate. In addition, this phenomenon can cause us to put aside the negative aspects of this product, adapting an enhancement or confirmatory strategy.