Scientists at the Virginia Tech Transportation Institute used cameras and sensors in cars to monitor more than 240 drivers, aged 18 to 73, over two million miles of driving around Virginia.
After the drivers were involved in 82 crashes and 761 near-crashes, the experts concluded that the vast majority were caused by inattention within three seconds of the incident.
Some 65% of near-misses were also caused by inattention, and nearly all of the rear-end crashes, although they did not always follow tailgating.
Those taking part in the test seemed to quickly forget about the equipment in their vehicles, and those monitoring footage were treated to some breathtaking displays. As well as bad driving, the participants got road rage and even drank beer and smoked marijuana behind the wheel.
Fatigue was identified as an issue in 22% of the incidents recorded, and sleepy drivers were found to be four to six times more likely to be involved in an accident.
However, in single-vehicle incidents, aggressive driving was just as big a factor.
The youngest drivers were those most likely to have an accident caused by inattention, with four times as many logged for those aged 18 to 20 than drivers older than 35.
Mobile phone use was identified as the most likely distraction on the road.
A spokesman for the research group said: ‘We’re spending a lot more time in our cars commuting and we’re doing a lot more in cars, especially with new technologies.
‘We do a lot of things and we don’t get caught. But in fact we’re just lucky and we get complacent. To the everyday driver, we’d like to say that any time you’re engaging in something else while driving, that really does increase your crash risk by two to three times.’
Paul Smith, founder of the UK-based Safe Speed road safety campaign, said: ‘This study shows that Government policy is focused completely on the wrong target.
‘If we want safer roads we must help drivers to improve. We should be helping drivers to help themselves by recognising the risks that arise through distraction and learning to avoid them.
‘Speed cameras add to driver distraction and workload. That’s one of the main reasons that they are a bad policy device.’