Most car accidents involving teenage drivers are caused by distractions such as phones, passengers, and personal grooming, according to a study released Wednesday.
Using video cameras installed in teens' cars, researchers concluded that 58 percent of the crashes they studied were caused by distracted drivers.
That is much higher than official estimates of 14 percent based on police reports.
The new study by the AAA Foundation for Traffic Safety examined 1,691 moderate to severe crashes (none fatal) that occurred from 2007 to 2013. In each case, researchers examined what drivers were doing in the six seconds before a crash.
The videos showed drivers reading phone text messages, making calls, applying makeup, chatting with passengers, dancing to music, and singing animatedly.
A compilation of some of the videos is available at www.aaafoundation.org/using-naturalistic-data-assess-teen-driver-crashes.
"Access to crash videos has allowed us to better understand the moments leading up to a vehicle impact in a way that was previously impossible," said Peter Kissinger, president and chief executive of the AAA foundation.
Teenage drivers have the highest crash rate of any age group. About 963,000 drivers aged 16 to 19 were involved in police-reported crashes in 2013, resulting in 2,865 deaths and 383,000 injuries.
The AAA study used crash videos from cameras installed by Lytx Inc., at the request of car owners who wanted insurance discounts or increased monitoring of their teenage drivers. The drivers were participating in a program intended to improve teen-driver safety and were aware their driving was being monitored, AAA said.
The in-car recorders collected video, audio, and speed data when triggered by hard braking, fast cornering, or an impact that exceeded a certain g-force. Each video was 12 seconds long, and provided information on the eight seconds before and four seconds after the trigger.
Most of the drivers studied were in Colorado, Illinois, Iowa, Minnesota, Missouri, Wisconsin, and Nevada.
The most common forms of distraction were:
Interacting with passengers (15 percent of crashes).
Cellphone use (12 percent).
Looking at something in the vehicle (10 percent).
Looking at something outside the vehicle (9 percent).
Singing/moving to music (8 percent).
Grooming (6 percent).
Reaching for an object (6 percent).
Distracted driving was blamed for 89 percent of crashes in which the vehicle left the roadway and 76 percent of crashes in which the vehicle rear-ended another vehicle.
Researchers found that drivers using their cellphones had their eyes off the road for an average of 4.1 out of the final six seconds before a crash.
The researchers also found that drivers using a cellphone failed to react in more than half of all rear-end crashes, meaning they struck the vehicle in front without braking or steering.
Since the drivers knew their behavior was being monitored, the researchers said distracted driving may be even higher among the general population of young drivers.