SEATTLE -- African Americans wait longer to get Uber and Lyft rides in Seattle and are more likely to have drivers cancel their trips, according to a new University of Washington and MIT study released Monday.

“Across all trips, the cancellation rate for African American sounding names was more than twice as frequent compared to white sounding names,” the study authors wrote.

Researchers sent passengers to hail nearly 1,500 rides on specific routes in Seattle and Boston and recorded the results.

Male passengers requesting rides in less-dense neighborhoods were more than three times as likely to have their trip canceled when they used an African American sounding name than when they used a white sounding name, the study found.

In Seattle, the time from ride request to dispatch for Uber and Lyft was about 20% longer for black passengers than white passengers, and it took about 30% longer for black passengers to get picked up, the study found.

The study also looked at taxi driver behavior and found some troubling patterns.

"Typically two extra taxis drove by our black students compared with our white students," said Don MacKenzie, a UW assistant professor of transportation engineering who co-authored the study.

The findings suggest Uber and Lyft make customers' accounts anonymous as a way to reduce discrimination, though the authors note that could lead some drivers to avoid certain neighborhoods altogether or to cancel trips as they are about to pick up passengers.

Another solution would be to create or strengthen penalties for drivers who frequently cancel trips. The study also suggests Uber and Lyft occasionally audit drivers to learn more about their behaviors.

"We really do believe these are the actions of individual drivers that are causing this, not the actions or the policy of the companies," MacKenzie said.

"We are extremely proud of the positive impact Lyft has on communities of color," said Adrian Durbin, a Lyft spokesman. "Because of Lyft, people in underserved areas—which taxis have historically neglected—are now able to access convenient, affordable rides. And we provide this service while maintaining an inclusive and welcoming community, and do not tolerate any form of discrimination."

Uber also issued a statement Monday afternoon:

“Ridesharing apps are changing a transportation status quo that has been unequal for generations, making it easier and more affordable for people to get around—no matter who they are or where they live. Discrimination has no place in society, and no place on Uber. We believe Uber is helping reduce transportation inequities across the board, but studies like this one are helpful in thinking about how we can do even more," said Rachel Holt, head of Uber North American operations.