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*Persuasiveness was measured using a restaurant review rate system with a nine-point scale.
The case for uncertainty: why lack of conviction can be convincing
by Hans Villarica
Nov 10, 2009
Stanford University researchers Uma Karmarkar and Zakary Tormala recently found that not everyone becomes more convincing when they express confidence in their opinions. The surprising exception involved experts who were actually less compelling when they showed conviction.
“When we started the research, we thought everybody would become more influential when they expressed more certainty,” Tormala said. “Instead, we found a much more interesting pattern whereby experts become more persuasive when they express uncertainty.”
Their findings, which are already available online, will appear in spring in the Journal of Consumer Research, a University of Chicago Press publication.
In the course of three experiments, researchers asked 313 participants to rate the persuasiveness of restaurant reviews that were supposedly written by either a non-expert or an expert. In reality, much of the content of the reviews were the same—only the tones of the reviews were altered to make the reviewer seem more or less certain about his recommendation.
The results revealed that non-experts became more persuasive when they expressed confidence. Among experts, however, the reviews that expressed some doubt about their recommendation had the greatest influence. The researchers credit this outcome to the shock value created by the counter-intuitive setup where experts—who are generally expected to be confident—expressed doubts in their opinions. Similarly, non-experts are generally expected to exhibit at least some doubt, so they’re more surprising and influential when they express confidence.
“The incongruity grabs people’s attention and draws them into the message,” Tormala said. “And being drawn in is a good thing so long as what’s being said makes sense and is compelling.”
Academics said the findings have significant implications in advertising.
“Marketers often use endorsers to communicate the key benefits of their brands,” said Aparna Labroo, a marketing professor of the University of Chicago Booth School of Business. “This paper shows that ad effectiveness might depend on the perceived expertise of the endorser and the certainty with which the endorser expresses his attitude.”
Psychologist Pablo Briñol of the Universidad Autónoma de Madrid in Spain agreed. “This research can be highly informative for those interested in persuasion through message framing, communication tailoring and market segmentation.”
