When her 20-year-old son is driving and his cellphone rings or receives a text message, Maureen Friar says she speaks up.

“I say, ‘You don’t need to get it, you don’t need to get it.’“

When she’s driving and her phone buzzes, she doesn’t always follow her own advice.

“In all honesty, I’ve probably modeled bad behavior,” says the consultant from Arlington County, Va. “So it’s a classic case of do as I say, not as I do.”

The parent as role model is not new to highway safety. In decades past, research showed that the parents who disdained seat belts or drove after drinking influenced the behavior of their teenage children to disregard those risks.

An online survey of 1,300 teen drivers with cellphones, scheduled for release today, found that even though their parents may warn them against it, most of those interviewed said adult drivers send text messages “all the time.”

A sizable proportion of the teens also admitted to engaging in the same dangerous practice. About the same number who said they saw their parents do it admitted to doing it themselves.

The new data — released as part of an effort by AT&T to combat distracted driving — conform with some of the work done by the Pew Research Center, which conducted surveys and focus groups two years ago with teenagers about smartphones.

“Often it was the parent who was engaging in dangerous behavior that the teens themselves thought was crazy,” said Amanda Lenhart, who directs Pew’s research on teens, children and families. “We heard from some teens who said, ‘My dad does it or my mom does it, but they do it in a safe way.’ Other teens would say things like, ‘It’s crazy, it totally freaks me out.’“

But just as with adults, research has shown that many teens who acknowledge the danger of smartphone use by other drivers admit that they do it themselves. Cellphone use by novice drivers has been banned in 30 states, including Maine, and Washington, D.C. Nevertheless, distracted driving was cited as a possible factor by the Governors Highway Safety Association this month when it sounded the alarm that teen highway deaths appeared to be creeping up after years of decline.

There is now a growing body of research that can be expected to find its way into the arsenal of arguments used by advocates who want state legislatures to ban drivers from all forms of mobile-device use behind the wheel.