It's well known that talking on a cell phone distracts a driver and increases the risk of a crash. Turns out driving distracts us from listening and talking, too.

"You might think that talking is an easy thing to do and that comprehending language is easy. But it's not," explained Gary Dell, a psycholinguist at the University of Illinois. "Speech production and speech comprehension are attention-demanding activities, and so they ought to compete with other tasks that require your attention – like driving."

Using a driving simulator, Dell and colleagues had volunteers work in pairs, one driving and one as a conversation partner who was either in the simulator with the driver or talking with the driver via a hands-free cell phone from a remote location.

They swapped stories, with the drivers hearing and retelling them. In one test, the virtual car just sat there during the conversation. In the other test, the car was moving and the drivers were driving. Afterward, the drivers were quizzed on what they remembered.

"The drivers remembered 20 percent less of what was told to them when they were driving" compared to when they were just sitting there, Dell said.

Declines in the accuracy of retelling the stories were most pronounced while drivers navigated through intersections or encountered more demanding traffic conditions.

"This study shows that various aspects of language go to hell when you're driving," said psychology professor Art Kramer, who collaborated on the study.

What's it all mean? Probably more confusion.

"With modern technology, we're talking more and more while we are doing other things, but we may be understanding one another less and less," Dell said.

The findings are detailed in the journal Psychonomic Bulletin & Review.