This is Scientific American — 60-Second Science. I'm Lucy Huang.

About 1.5 billion people speak English around the world. But for more than 1.1 billion of them, English is their second language — often with a noticeable accent.

"Your accent really reveals a lot about who you are and your identity. It will tell people what your native language is, be able to tell you probably where you come from." Marc Pell, a communications professor at McGill University in Montreal. And according to Pell, one reaction to a different accent can be a bias against that person.

"Previous research that has been done elsewhere showed that people who have an accent tend to be trusted less, simply because they have an accent. But the idea that we would have a bias against anyone who sort of doesn't sound like us I think probably relates to some sort of evolutionary or long-standing suspicion we have of outsiders or strangers. So this might be sort of an ingrained response that we have to the accent."

But accents aren't the only thing we listen for when we have to decide if we trust another person. Tone of voice also plays a role. Pell and his team wanted to know if people would trust a confident tone, even if it came from someone with an accent.

The researchers had Canadian English speakers listen to different versions of people saying neutral statements like she has access to the "building" while they were getting a brain scan in an MRI machine. Subjects heard someone say it with a confident neutral tone with a Canadian English accent, an Australian accent or a French accent. Participants also heard the sentence with the three accents spoken in a doubtful or neutral tone.

The MRI scans showed that the participants had to use more brain power to decide if they could trust the statements said with the non-native accents. When the study participants heard the Australian or French accents, blood flow increased to the temporal lobe, part of the brain that we use to process sound.

MP: "They seem to have to analyze that perhaps more intensively or, or for a longer period of time to make this decision about whether they truly believed the speaker."

The work is in the journal Neuro Image.

When asked, the participants reported not trusting either Australian or French accents — except for when the statements were said confidently. Seems that confidence speaks for itself.

Thanks for listening for Scientific American — 60-Second Science Science. I'm Lucy Huang.