A police officer is more likely to address a White person as “sir” or “ma’am” during a traffic stop, but a Black person would be addressed by their first name or other informal titles like “man,”  a new study has found. 

The study, which was published in the Proceedings of the National Academy of Sciences on Monday, said that police officers spoke significantly less respectfully to Black people compared to White community members in routine traffic stops.

Researchers used footage from the body cameras of police officers in Oakland, California, to conduct the study. They analyzed 183 hours of body camera footage that was taken during 981 routine traffic stops by 245 Oakland Police Department officers in April 2014.

The study found that White people are about 60 percent more likely to be spoken to respectfully, while Black people were 60 percent more likely to hear less respectful instructions like, “Do me a favor,” or “Keep your hands the steering wheel.” Police officers tended to speak less respectfully to Black drivers within the first few minutes of the traffic stop, even if unprovoked, or even before the driver has said much.

The reason for the stop did not impact the officers’ level of respect. 

The study was led by Rob Voigt, a doctoral student in the linguistics department at Stanford University. The researchers wrote, “Routine traffic stops are not only common, they are consequential, each an opportunity to build or erode public trust in the police.” 

“Indeed, some have argued that racial disparities in perceived treatment during routine encounters help fuel the mistrust of police in the controversial officer-involved shootings that have received such great attention.”

Voigt told CNN that it was worth investigating whether this racial disparity in language happens in other communities across the US.

“At the very least this provides evidence for something that communities of color have reported, that this is a real phenomenon,” said Voigt.

Researchers concluded that “regardless of cause, we have found that police officers’ interactions with Blacks tend to be more fraught, not only in terms of disproportionate outcomes (as previous work has shown) but also interpersonally, even when no arrest is made and no use of force occurs.”