People have to "walk the line" for a sobriety test because you shouldn't drive if you can't walk. But driving may be just as dangerous if you plan to talk.
A study published today is providing the first peer-reviewed scientific evidence that driving and talking on a cell phone could be just as bad as drinking and driving.
"If you do a carefully controlled study where you equate for the amount of time that people are driving and the driving conditions, you're actually worse off when you are using a cell phone than when you're legally drunk," says David Strayer, a psychologist at the University of Utah.
Strayer had announced some preliminary data from his study at a scientific meeting in 2003. It took until now for the study to be completed, undergo review by other researchers and finally be published. The work builds on previous research of his which showed that that talking on a "hands-free" cell phone impairs driving just as much as when the phone is in your hand. So he wanted to know how talking compared to the ultimate driving impairment.
"So we had people come in one day and we got them legally drunk, with a blood alcohol level of .08," says Strayer. "And then we measured how they drive in our driving simulator."
The simulator is a $100,000 virtual reality driving machine in which volunteers follow a pace car. The simulator measures how fast, accurately and aggressively the driver follows the route. At the same time an eye tracking device measures where the driver is looking the whole time. Forty volunteers drove the car on four different mornings: once while legally intoxicated, once while talking on a hands-free cell phone, once while talking on a hand-held cell phone, and once with no distractions.
As Strayer wrote in the journal Human Factors, drunk drivers were more aggressive, tailgated more, and hit the break pedal harder. Cell phone drivers took longer to hit the breaks, and got in more accidents. (There was no difference between hands-free and hand-held cell phone drivers.) Strayer notes that these are different results, but both are dangerous, and "in both cases you were significantly impaired."
That said, Strayer and his colleagues do not want to trivialize the dangers of driving drunk. According to the U.S. Department of Transportation, the drivers in the majority of fatal DWI accidents are, on average, twice as intoxicated as Strayer's volunteers, based on their blood-alcohol level. And Strayer points out that while most of those fatal accidents happen late at night, when drivers are also fatigued, his simulations happened in the morning after participants had supposedly had a night's sleep.
But most of all, he hopes his work has a sobering influence that prevents people from dialing and driving.