Up to half of teens talking on cellphones while driving are speaking with their mother or father, according to new research.

A lot of parents aren't really aware of how important it is to be a good role model and how dangerous it is for their teen to answer a cellphone while driving," said study author Noelle LaVoie, a cognitive psychologist and president of Parallel Consulting in Petaluma, Calif.

"There is certainly [prior research] showing that parents might not be modeling the best behavior for teens," she added, "and we know a lot of parents talk on the phone while driving. But this was a real shock."

The findings were scheduled to be presented at the American Psychological Association's annual meeting in Washington, D.C.

Distracted driving causes 11 percent of fatal crashes among teens, and 21 percent of those crashes involve cellphones, according to a 2013 report by the U.S. National Highway Traffic Safety Administration. And, another recent study found that as many as 86 percent of 11th and 12th graders admit to using their cellphones while driving.

Teens have previously reported seeing their parents and others use their cellphones while driving, which makes it seem as if it's the social norm, according to the study authors.

For the study, researchers interviewed or surveyed about 400 drivers aged 15 to 18 in 31 states. Teens with learner's permits were the least likely to talk and drive -- 43 percent of them didn't use a phone. When 16- to 17-year-olds were given an unrestricted license, just 29 percent chose not to use their phone while driving. By 18, that number dropped to only 10 percent who didn't talk and drive, according to the study.

Among the participants, more than one-third of the 15- to 17-year-olds and half of the 18-year-olds said they talked on the phone with a parent while driving.

Teens were slightly more cautious about texting and driving. Almost two-thirds of teens with learner's permits didn't text while driving. By the time teens were 18 with an unrestricted license, that number dropped to just over one-quarter.

Teens were more likely to text friends than parents while driving. But, 16 percent of 18-year-old drivers had texted a parent while behind the wheel and 8 percent of 15- to 17-year-olds had done the same, according to the researchers.

Teens told the researchers that their parents expect to be able to reach them, and that they may get mad if they can't contact the teens.

Source: U.S. News & World Report
http://health.usnews.com/health-news/articles/2014/08/08/distracted-teen-drivers-often-on-cellphone-with-parent-study