'Sleeper effect' accounts for durability of weak messages from credible sources

When a weak argument is delivered, a source-based "sleeper effect" can arise -- that is, the influence of the message can increase over time as it permeates the public sphere. But the dormant effect occurs only if the credibility of its source remains strong, says Dolores Albarracin, a professor of psychology at Illinois.

"We started to look at the delayed impact of communications, and the sleeper effect is a classic topic for persuasion research," Albarracin said. "The sleeper effect shows that a strong message from a noncredible source has a delayed effect, so it's more persuasive after time has gone by. We researched this effect for a long time, and we came to the realization that it was happening when people focused on the message's arguments -- but the source was an afterthought. So we turned things around and asked, 'What if people focus on the credibility of the source?'"

If a message can be discounted for its association with a noncredible source, "we wanted to see if it could also be discounted for containing weak arguments, as well," Albarracin said.

To test their hypothesis, Albarracin and her co-authors -- G. Tarcan Kumkale of Kadir Has University and Patrick Poyner-Del Vento of Simon Fraser University -- asked participants to evaluate the campaign materials of a fictitious political party running for the student government on campus.

Each participant received two ads: One describing the arguments of the party with either strong or weak arguments; the other introducing the attributes of the candidates, who were portrayed as either credible or noncredible.

"These two ads allowed us to generate two conditions -- one with strong arguments presented by a noncredible source and the other with weak arguments presented by a credible source," she said.

The researchers found that when a credible source presents weak arguments, a source-based sleeper effect can be observed because the influence of the credible source endures.

"It turns out that, over time, a credible, strong communicator presenting a weak message or making a weak claim about an issue is able to convince people, even though the issue or the argument is weak," Albarracin said. "What happens is that there's a transfer of the positive or negative attributes of the source to the recipient's attitude about the position and the message. The only caveat is that it doesn't happen immediately; it takes time. It also happens when recipients are centered on the communicator more than the issues."

By contrast, a message -- even a credible one -- produced by a weak communicator with little credibility has no effect early on. But later on, there's a zombie effect.

"What is surprising about the classic sleeper effect is that, later on, this really weak communicator ends up convincing you, without you realizing it to some extent, because by then you've forgotten the weakness of the communicator," Albarracin said. "Thus, the sleeper effect."

A noncredible source coupled with a strong argument has the sleeper effect of the more it gets out there, the more currency it gains and the more traction it gets in the public consciousness.

"The public forgets about what seemed suspect about a communication," she said. "They forget that they heard it first from someone who should be discounted. So something that wasn't effective early on might have an effect down the line because people forget who initially said it."

The research is especially relevant for communication that's aimed at persuasion, said Albarracin, also a professor of business administration.

"Communications tend to be tested in a neutral, baseline situation without really taking into account the mindset of its recipients," she said. "In real life, people have to make decisions: 'Who do I vote for?' 'Which of these two competing products do I buy?' That mindset -- focusing attention on either the message or the speaker -- isn't usually a part of persuasion research."

For instance, if your company had a credible brand but a weak product, consumers might test the product but not be persuaded to buy. Later on, however, they might "forget details about the testing experience and actually look more positively toward that product," Albarracin said.

"When launching a campaign or a product, or building some sort of program, how do you measure initial versus downstream impact? Does it have a little bit of an initial impact that quickly fades away? It's much rarer to find impact later down the line, but we find that it does actually happen."