Back in 1992, language expert Donald Rubin got some unsavory results.

Earlier that year he had held a fake class for about 60 undergrads at the University of Georgia, in front of whom he placed either a photo of a Caucasian professor or a Chinese professor. In both of these photos, the professors were dressed similarly, with matching hairdos, and were seen standing in front of identical chalkboard backdrops. Each was accompanied by the same voice, which was a woman from Ohio reciting two articles in The New York Times. The only difference between the two professors was their face, which gave away their nationality.

Rubin was tweaking an earlier experiment that had shown students almost always gave poorer ratings on foreign professors with an accent. The common assumption among scientists was that this effect stemmed from the foreign professors' poor communication in the classroom. But Rubin suspected that these students had a negative bias against their foreign professors as well. So this time, he chose to eliminate the communication factor altogether. If students held no biases, they should retain lecture material equally as well when delivered by either professor. After all, it was the same woman speaking.

Hallucinating accents

But that wasn't the case. Following the lectures, students were asked to recall what they had learned and "it revealed something really interesting," says Carina Bauman, a New York University sociolinguist who studies Asian accents. Though the same person was speaking to them, the students reported that the pictured Chinese professor had lectured in "a more foreign" accent, Bauman says, which made them recall less of the class when it was taught by her. "Basically, it showed that it's possible for people to hallucinate a foreign accent," Bauman says. When the students saw the Chinese professor's photo, their brain summoned an accent, which they had most likely heard delivered by someone with a similar face before.

Molly Babel, a linguist at the University of British Columbia in Vancouver, Canada, replicated Rubin's study this year. More than 20 years later, Babel uncovered exactly the same bias that Rubin had. Students actually understood Chinese Canadian and Caucasian Canadian speakers equally as well when they didn't see either of their faces, Babel says. "It's only when listeners saw a picture of the Chinese Canadian speaker that their ability to accurately understand them went down."

In other words, Rubin was right in his hunch. It was the students' own biases, and not the teachers' bad communication, that led to poorer ratings of foreign professors. The students were simply not listening to their teachers.

Let me correct you

The results of Rubin and Babel's studies suggest that regardless of the clarity of foreign speakers, we still expect to understand them less. Some scientists even argue that we anticipate what they say will be less accurate.

"We expect the speech of non-native speakers to be less reliable, so we are always inferring what they will say," says Shiri Lev-Ari, a psychologist at the Max Planck Institute for Psycholinguistics in The Netherlands. .

Indeed, one 2013 study suggests that we slip in what we think a foreign speaker means to say, particularly when their accent has low social standing. Linguists from Stanford had students listen to a list of words like bed, pillow, nightstand, and dreams read by either a high-prestige British accent or a working-class New Yorker accent. Later, the students were asked to jot these words down from memory.

When the researchers purposefully left one word off the list and asked the students to write what they heard once again, the students had a much higher false memory rate for the speaker with a working class accent, Babel says. Even though the New Yorker didn't say pillow, for example, students still wrote pillow down. This "filling in" occurred less when the British voice left a word out, which suggested to the researchers that the students believed the Brit must have said what he meant.

Prejudice or a lazy brain?

Some of this double-standard for trusting voices differently comes from the stereotypes tied to accents. But it is also possible that we just prefer the tune of voices similar to our own, and thus understand it better. In fact, Lev-Ari says, we have lazy brains that prefer inputs that are easy to process. In this case, this would be the listener's' own native tone, pace, and volume level.

In her own 2010 experiment, Lev-Ari asked native English speakers, as well as English speakers with heavy foreign accents, to deliver a pub-style trivia statement. For example, "A giraffe can go without water longer than a camel can." Native English listeners then judged whether or not this fact was true. Lev-Ari saw, as expected, that listeners were more likely to take a statement as true when it was said by a fellow native speaker. Statements were seen as less credible when relayed by anyone speaking in a foreign accent.

"Accents require more cognitive effort to process," Lev-Ari says. "If something is easier to understand, we're more likely to retain it and see it as credible."

OK, maybe lazy, but still not fair

But a lazy brain isn't a free pass. And bias against accents can have ramifications beyond just hurt feelings. In court, accent discrimination cases "almost universally lose," Bauman says. Defendants will argue that, say, a housing rental application was turned down not because of accent or ethnicity, but because "the person was just too difficult to understand." Though it's highly illegal to deny any sort of service based on race, ethnicity, or national origin, she says, "it remains very difficult to prove discrimination on the basis of accent." Perhaps, this happens because culturally, it remains acceptable to have prejudice against foreign accents, as some have argued. Unlike with other facets of diversity like race and ethnicity, society has yet to cross the leap into consciously thinking about how we view individual differences as marked by accent.

How do I fix this?

Aside from eliminating your accent, "which there's a lot of debate on how feasible it even is to completely do that," Bauman notes, there aren't many options for the speaker in this situation. Rubin wrote in Research in Higher Education that "it makes sense" to not only urge foreign professors to drop their accents, but to also educate students on how to listen to someone unlike themselves. Modern linguists agree that the best way to do this—to train your brain and to rid yourself of biases—is to spend more time with people who act, look, and speak differently from you. After all, as Rubin noted, "Communication is a reciprocal process."