(CNN)-Police officers conduct themselves differently during traffic stops with Black and White drivers, even down to the subtlest of details, new research suggests.

A study from the American Psychological Association published Monday finds that police officers exhibit less warmth and respect in their voices when talking to Black drivers than they do with White drivers.

Researchers sought to examine how officers sound during interactions with Black and White Americans and how their tone of voice affects institutional trust of law enforcement.

"One of the things that was missing from [previous] studies was that it matters not just what people say, but how they say it," said Nicholas Camp, an assistant professor of organizational studies at the University of Michigan and lead author of the study.

Read the full article at CNN.