Cops Talk Less Respectfully to Black People Than White at Traffic Stops, According to Science

Cops talk differently and more negatively to Black drivers than white ones during traffic stops, a study shows.
A new study shows that police officers use a different tone for Black drivers at traffic stops than for white.
A new study shows that police officers use a different tone for Black drivers at traffic stops than for white. (Photo by Stan Lim/Digital First Media/The Press-Enterprise via Getty Images)

Cops are more friendly to white drivers than Black during traffic stops—and now, science proves it.

In a study published earlier this week in the Journal of Personality and Social Psychology: Attitudes and Social Cognition, a group of researchers and professors analyzed the audio from traffic stops to understand if cops treat Black and white men differently during these encounters.

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The big reveal: Cops talk differently and more negatively to Black drivers than white ones during traffic stops, aggravating tension between law enforcement and minority communities.

The study, conducted by researchers from elite universities, had test subjects listen to audio recordings from a medium-sized U.S. city’s police department body-camera audio. The sample included a pool of 100 clips where a Black person was stopped and 100 clips where a white person was stopped. They then used a new pool of 200 for a second study to ensure the results were robust. 

When they analyzed the audio, they muffled both the civilian’s voice and the officer's voice so that participants couldn’t tell what race they were or what was being said—just their tone of voice. The researchers had participants rank an interaction on a scale of 1 to 6, with 1 meaning the officer in the audio clip was “very cold” and 6 meaning “very warm.”  Then they asked whether the officer’s tone was more or less tense, friendly, or respectful toward the driver.  The results were undeniable: Cops are less friendly to Black men. 

Nicholas Camp, a social psychology professor at the University of Michigan, and the other researchers discovered that participants in the study would categorize an officer’s speech as “talking down” and “tense” when interacting with Black drivers, and rarely “friendly” when compared to their tone in traffic stops with white drivers. 

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“Police officers are simultaneously representatives of the state and the human face of the law; as a result, these interpersonal interactions have institutional consequences,” Camp wrote. “Racial disparities in cues as subtle as an officer’s tone of voice can shape citizens’ trust in the police and alter their interpretations of subsequent encounters.”

The results of the study showed that with Black drivers, officers displayed an attitude of 3.50, “neither positive nor negative,” and with white ones, they scored an average of 3.72, or “more positive.”

Though the difference is small, Camp told VICE News it’s important to think about how little information was given to participants and how isolated each reaction was—over time, the difference can be exponential. The researchers noted that these numbers held up regardless of other qualifying factors, like race, age, or gender, of the cop making the stop. 

“They’re not huge, but that’s not the point,” Yale law professor Tracey Meares told the LA Times in commenting on the study results. “The point is that there are differences that can be detected.”

The study’s other authors included Rob Voigt, a linguistics professor at Northwestern University; Dan Jurafsky, a computer science and linguistics expert at Stanford; and Jennifer Eberhardt, a psychology expert also at Stanford.

The study also took note of each participant’s previous interactions with police, and showed that if someone has had a prior negative interaction with a cop, they’re inclined not to trust them. With two-thirds of Black Americans saying they don’t trust cops, according to PBS, this treatment only fuels the tension with police.

Camp said he hopes the study shows cops that “things like communication in these routine encounters is not the flashiest, it’s not the sexiest aspect of policing—but it's important.”