NEW YORK (CNN/Money) - Cell phones are the distraction that people love to hate, but researchers said Wednesday that drivers are preoccupied more often with the radio, eating, or grooming while behind the wheel.

Researchers with the AAA Foundation for Traffic Safety installed video cameras in the cars of 70 volunteer drivers. Half the drivers were from Pennsylvania, the rest from North Carolina. Half were men and half women.

The volunteers were aware that there was a camera installed in their vehicle, but they were told that researchers were studying traffic conditions. The drivers were unaware that the cameras were actually recording the drivers' activities.

"We saw people driving while doing all kinds of stuff," said Mantill Williams, a AAA spokesperson. "What you're seeing is the cleaned-up version."

The researchers found that all 70 motorists it watched were distracted at some point by conditions inside and outside the vehicle during a three-hour period.

All drivers were distracted up to 16 percent of the time while the vehicle was moving. This did not include conversations with passengers, according to the study by the University of North Carolina's highway safety research center.

"People often underestimate the seriousness of distractions because not every distraction leads to a crash," said Peter Kissinger, president of the AAA's traffic safety foundation. "But if you are distracted just when someone pulls out in front of you, your lack of attention can be catastrophic."

Driver distractions In the AAA Foundation's video observations, these were the activities drivers engaged in most often. Activity  Percent of drivers  Percent of time  Reaching, leaning, etc.  97.1  3.8  Manipulating stereo controls  91.4  1.4  Eating, drinking, etc  71.4  15.3  Conversing  77.1  4.6  Grooming  45.7  0.3  Passenger  44.4  0.9  Reading or writing  40.0  0.7  Using cell phone  30.0  1.3  Smoking  7.1  1.6   70 drivers observed for three hours  Source:  AAA Foundation for Traffic Safety

An estimated 25 percent of all traffic crashes are caused by distractions, highway safety figures show. In a survey of actual crash data conducted by the foundation last year, adjusting the radio was involved in 11.4 percent of "distracted driver" crashes. That was a higher percentage than for anything except "outside object, person or event." Using a cell phone was involved just 1.5 percent of the time. In that study, researchers looked at crash data collected by the national Crashworthiness Data System between 1995 and 1999.

In the recent video observation study, about one-third of the motorists studied in North Carolina talked on a cell phone while driving, but 25 percent of that use occurred when the vehicle was stopped.

Just about all of the drivers manipulated music or audio controls, while 71 percent ate or drank. About half groomed themselves and 40 percent read or wrote. Most of the reading and writing and a third of grooming occurred when the car was stopped.

The grooming included such things as using a toothpick, taking pills, applying lipstick and combing hair. The reading and writing included checkbooks, newspapers and mail.

"We found that people do adjust their behavior to a certain extent," Kissinger said. "They have a tendency to do potentially distracting things when their car is stopped."

Researchers said older drivers engaged in less distracting behavior but no age group was immune. None of those taped in the auto safety study knew that driving distraction was being measured. They were told the research was to find out how traffic and road conditions affected driver behavior.

The study was the second phase of research by the North Carolina group. "We hope that this real-world data will provide a useful baseline for future study," said Jane Stutts, the lead researcher.