A new report from researchers at Stanford University found what many Black people already know: Police are more likely to speak disrespectfully to Black people than they are to their White counterparts.

Proceedings of the National Academy of Sciences posted “Language From Police Body Camera Footage Shows Racial Disparities in Officer Respect” online yesterday (June 5). The three-part study was the collaborative effort of researchers in Stanford’s Departments of Linguistics, Psychology and Computer Science. The report examines Oakland Police Department body camera footage for 981 stops conducted by a total of 245 officers in April 2014. Researchers analyzed 36,738 utterances from officers on the 183 hours of interaction video footage.

In the first part of the study, they tested to see if humans can reliably judge levels of respect based on the language used by the officers. Participants were asked to read statements—which were scrubbed of names, races and genders—and rate them for respectfulness, politeness, friendliness, formality and impartiality. The testers found that the statements directed at Black drivers were less respectful, polite, friendly, formal and impartial, even when controlling for age and gender. They found the officers were equally formal with Blacks and Whites.

In the second and third parts of the study, researchers removed human evaluators from the equation and used linguistic models to analyze first 414 utterances, and then all 36,000+ utterances, to judge respect and formality. The results: The computer also concluded that officers are less respectful to Black drivers. The chart below shows how likely officers are to use specific phrases when talking to Black and White drivers.

As the report explains: “For example, apologizing, gratitude and expressions of concern for citizen safety are all associated with respect. The bars on the right show the log-odds of the relative proportion of interactions in our dataset taken up by each feature, where negative numbers mean that a feature comprised a larger proportion of officers’ speech in interactions with Black community members and positive numbers mean the same for interactions with White community members.”

The following graphic provides examples of how this language is used during stops.

Overall, the study found that White people are shown more respect, with Whites being 57 percent more likely to be addressed with the most respectful statements, and Blacks 61 percent more likely to be disrespected. Also key: not only does the race of the officer does not have a significant impact on that finding, but the difference is evident from the first seconds of the interactions—before the people who have been stopped even have a chance to speak. There was not a difference in respect when offense severity was considered, and for the stops where geographic information was available, crime rate did not matter (though high-crime areas did increase formality).

The researchers don’t arrive at a cause for the differences, but they do write about the impact:

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. These disparities could have adverse downstream effects, as experiences of respect or disrespect in personal interactions with police officers play a central role in community members’ judgments of how procedurally fair the police are as an institution, as well as the community’s willingness to support or cooperate with the police.

Read the full report here.