National Geographic News
Young drivers who use cell phones at the wheel drive like the elderlywith slower reaction times and an increased risk of accidentsa new study shows. And what's more, hands-free phones are no safer than handheld ones, scientists behind the study say.
"If you put a 20-year-old driver behind the wheel with a cell phone, their reaction times are the same as a 70-year-old driver who is not using a cell phone," said David Strayer, a University of Utah psychology professor and principal author of the study.
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"For five years or so we've been interested in what happens when someone picks up a cell phone and starts to drive," Strayer said.
One thing that appears to happen is that phone-using drivers of all ages have significantly diminished reaction times. They are slower to hit the brakes and more likely to get into accidents.
Subjects took "freeway drives" in a simulator, using a hands-free mobile phone for half of the drive.
"We're seeing an 18 to 20 percent slowing [of reaction times]," Strayer explained. "That means if someone is talking on a phone, it takes them longer to hit the brakes. They are more likely to get into an accident, and if they do get into one, it might be more severe, because they won't be able to decelerate as much. What you've effectively done is made the reactions of a 20-year-old comparable to those of a 70-year-old."
The deteriorating responses can have serious repercussionsresults of this and previous simulator-based studies show that the number of rear-end collisions double for phone-using drivers.
Perhaps to compensate for slower reaction times, cell phone users also increased the distance between their cars and cars ahead of them by some 12 percent.
Elderly drivers saw similar declines in reaction times when they took the wheel with phones. In a bit of a surprise, however, their reactions did not deteriorate at a greater rate than those of their younger counterparts.
"We see in the lab that older adults tend to have slower reaction times in general and also sometimes have difficulty multitasking relative to maybe a 20-year-old," Strayer said.
But in the study the 20 older subjects (average age: 70) suffered no greater impairment than their 20 younger colleagues (average age: 20).
Phone users of all ages also took 17 percent longer to return to the speed of traffic after braking. Such sluggish driving can affect the likelihood and severity of rear-end collisions and help to create gridlock, especially when many drivers display such behavior.
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