Training police officers on effective communication through body-worn camera analysis can improve their interactions with community members, a new University of Michigan study suggests.

In an analysis involving the Oakland (California) Police Department, officers who received procedural training expressed more reassurance, safety concerns and clearer justifications during traffic stops.

The findings come as public concerns about questionable police behavior caught on body cameras continue to make their way into the news media. Law enforcement interactions with the public are often invisible in the data used to evaluate, said lead author Nicholas Camp, U-M assistant professor of organizational studies.

“Today the bulk of police-community interactions remain out of sight not only because they are unrecorded, but also because even when they are recorded, the footage goes unobserved,” he said.

Using body camera footage, Camp and colleagues analyzed the words used in traffic stop recordings to detect whether officers enacted the five behaviors addressed in the training. They include: initiate with a greeting; state reason for stop early on; offer reassurance; express concern for safety; and use formal rather than informal titles.

The sample included more than 120 officers and 600 traffic stops.

Compared to recordings of stops that occurred before the officer’s training, the researchers found that officers employed more of these techniques in post-training stops four weeks later—officers were more likely to express concern for drivers’ safety, offer reassurance and provide explicit reasons for the stop.

“Our findings illustrate how training might improve police-community conversations, how AI tools can be used to help analyze these conversations, and, more broadly, how body camera footage can be used to affect and measure change,” Camp said.

As it relates to drivers’ racial backgrounds, most of the stops involved Black and Hispanic drivers. OPD officers employed more respectful language with white drivers vs. other ethnicities in traffic stops.

Oakland’s police department, as part of a court-ordered negotiated settlement dating back to 2003, was required to institute procedural justice training for all sworn personnel, starting in 2014. Other police agencies have added similar training to improve police-community relations, Camp said.

The OPD’s training—”Procedural Justice in Motion”—was deployed over 41 sessions conducted during eight months in 2017-2018. Only 36% of the department’s officers attended a session that they were originally assigned.

Given the racial disparities that motivated the training, did the training improve officer interactions with Black community members? Or did it merely improve already respectful interactions with white drivers? Camp said the answers are constrained by the study’s sample size, the large number of stops of Black drivers compared to other ethnic groups, and the many stops.

Nevertheless, the use of body camera footage “holds promise as a tool to capture gaps in police interactions, to orient training towards those processes and to measure progress in improving them,” Camp said.

The study, which appears in PNAS Nexus, was co-authored by Rob Voigt of Northwestern University and MarYam Hamedani, Dan Jurafsky and Jennifer Eberhardt of Stanford University.