"These days, you can easily find recommendations from experts or even other consumers about any product or service you might be interested in," write authors Uma R. Karmarkar and Zakary L. Tormala (Stanford University). "But what are the factors that can make these people's recommendations more or less influential?"

Across three experiments, the researchers presented participants with a restaurant review from either a novice or an expert, and looked at how that source's expressed certainty or uncertainty about his or her review influenced the effects of the message. "We predicted that mismatches between the source's level of expertise and the level of expressed certainty, or confidence, would lead people to be more persuaded by a good and compelling review," the authors explain. "In other words, a novice would be more persuasive when he expressed certainty about his opinions, whereas an expert would be more persuasive when he expressed uncertainty."

The study confirmed the researchers' predictions. "Participants found the restaurant review more surprising and unexpected when a novice reviewer expressed certainty, or when an expert reviewer expressed uncertainty," the authors write. "Investigating further, we found that when the level of certainty expressed was incongruent with the source's expertise, it increased involvement with the restaurant review."

"In the context of product or service reviews, being confident in your opinion does not necessarily mean that you'll be perceived as more convincing," the authors write. "Paradoxically, an expert or "gold star" reviewer on a website could draw more people in to his review if he was willing to be modest or admit uncertainty about his views. But for all that attention to pay off, he'd have to ensure he had good strong reasons supporting his opinion."

Note: If no author is given, the source is cited instead.

• Consumer Behavior
• Perception
• Psychology

• Problem solving
• Illusion of control
• Belief
• Macroeconomics
• Social psychology
• Ego psychology