If a teenager is talking on the phone while driving, chances are good that they’re talking to a parent.

More than half of teen drivers reported talking to their mother or father on the phone while driving, according to a new study presented at the American Psychological Association’s annual convention Friday. The calls from parents play a direct role in distracted teen driving, researchers said.

"Teens told us parents really expected to keep track of them, and they are expected to answer the phone if the parent calls,” lead researcher Noelle LaVoie told USA Today. “In some cases, the parent might continue to call until the teen answers.”

Researchers surveyed about 400 drivers between the ages of 15 and 18 from 31 states. Of those who said they used their phone while driving, 53 percent reported talking to a parent. Forty-six percent said they talked to a friend.

The same teens reported seeing their parents use a cellphone while driving, according to the study. A recent report from the AAA Foundation for Traffic Safety found more adults use their phones while driving than teenagers with 82 percent of adults ages 25-39 saying they used their phone while driving compared with 58 percent of teens.

"There is certainly (prior research) showing that parents might not be modeling the best behavior for teens and we know a lot of parents talk on the phone while driving, but this was a real shock," LaVoie told CBS News.

Fewer teenagers reported texting while driving than speaking on the phone, but those who did text were more likely to text friends than their parents. Sixteen percent of 18 year olds with an unrestricted license said they texted parents while driving, compared with 57 percent who said they texted friends. Twenty-six percent did not text at all while driving.