A foreign accent undermines a person's credibility in ways that the speaker and the listener don't consciously realize, new research at the University of Chicago shows.

Because an accent makes a person harder to understand, listeners are less likely to find what the person says as truthful, researchers found. The problem of credibility increases with the severity of the accent.

"The results have important implications for how people perceive non-native speakers of a language, particularly as mobility increases in the modern world, leading millions of people to be non-native speakers of the language they use daily," said Boaz Keysar, a Professor of Psychology at the University of Chicago and an expert on communication.

"Accent might reduce the credibility of non-native job seekers, eyewitnesses, reporters or people taking calls in foreign call centers," said Shiri Lev-Ari, lead author of "Why Don't We Believe Non-native Speakers? The Influence of Accent on Credibility," written with Keysar and published in the current issue of the Journal of Experimental Social Psychology. Levi-Ari is a post-doctoral researcher at the University whose work focuses on the interactions between native and non-native speakers.

To test the impact of accent on credibility, American participants were asked to judge the truthfulness of trivia statements by native or non-native speakers of English, such as, "A giraffe can go without water longer than a camel can."

Simple prejudice could affect ratings of truthfulness, so the researchers tried to minimize that effect by telling participants the information in the statements was prepared for the speakers, and was not based on the speakers' own knowledge.

Despite knowing the speakers were reciting from a script, the participants judged as less truthful the statements coming from people with foreign accents. On a truthfulness scale prepared for the experiment, the participants gave native speakers a score of 7.5, people with mild accents a score of 6.95 and people with heavy accents a score of 6.84.

"The accent makes it harder for people to understand what the non-native speaker is saying," Keysar said. "They misattribute the difficulty of understanding the speech to the truthfulness of the statements."

In a second experiment, researchers tested whether awareness reduces the impact of accent on perceived truthfulness. Researchers told participants that they were being tested to see if accents undermine credibility.

That experiment was conducted with identical recorded statements, but with different results. While participants rated statements with mild accent just as truthful as statements by native speakers, they rated heavily accented statements as less truthful, Lev-Ari said.

Accent is one of the factors that influences people's perception of foreigners in a society, Keysar pointed out. But its insidious impact on credibility is something researchers had not previously known, he added.

The research was supported with a grant from the National Science Foundation.

Listen to Statements Used for the Study