From the Department of Obvious But Still Interesting Findings: A new study concludes that drivers chatting away on their mobiles probably slow down the daily commute. Even the hands-free talkers are guilty. On average, drivers carrying on phone conversations drive about two miles per hour slower in commuter traffic conditions, and fail to keep up with the flow. According to one of the authors, David Strayer, a psychology professor at the university of Utah, this could add up to 20 hours per year of travel time.

In the study, three dozen students drove in simulators, and the ones talking on the phone were more likely to stick behind slow drivers, and less likely to change lanes. In the real world, given that 10 percent of commuting drivers, on average, are probably chatting away, this inattention adds up.

What we’d like to know, though, is how, or whether, these findings could explain the fast-talking taxi drivers who spend all day and night jabbering away into their mics, yet still manage to switch lanes more than any group on the planet. Let’s get them in the simulator and see what happens.—Gregory Mone