Young Cell Phone Users Drive Like Elderly, Study Says

Brian Handwerk
National Geographic News
February 2, 2005
Young drivers who use cell phones at the wheel drive like the elderly—with slower reaction times and an increased risk of accidents—a 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.

"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 repercussions—results 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.

Strayer and co-author Frank Drews, assistant professor or psychology, published their findings in this winter's issue of the journal Human Factors.

Hands-Free Units Not Much Help

Strayer and his group employed only hands-free phones for testing. Some states, including New York and New Jersey, have enacted safety legislation that restricts drivers to hands-free mobile phone use. But many researchers say the laws aren't enough—and may be completely useless.

"We have research that concludes that the use of a phone, whether handheld or hands-free, can have [the same negative] impact," said Rae Tyson, spokesman for the U.S. National Highway Traffic Safety Administration (NHTSA).

In fact, NHTSA studies at the University of Iowa suggested that in some cases, hands-free devices could pose a greater risk, because tasks like dialing can be more difficult and take longer.

The University of Utah team's research delivered similar results.

"The distinction some laws make between hands-free and regular phones doesn't stand up to scientific scrutiny," Strayer explained. "We've done studies, and other studies in Sweden and Australia have all come to the same conclusion: that it's a very similar signature of impairment."

The distracting effects of cell phones are attributed largely to the conversations themselves, which draw a driver's attention away from the road. The effect is dubbed inattention blindness.

"Not to say that dialing isn't a problem, but you can probably develop work-arounds where your hands are off the wheel for a limited amount of time," Strayer said. "Drivers engage in multitasks, like eating a sandwich or tuning the radio, when they perceive a lull in traffic and think it's safer. People are not too bad at judging those lulls if it's a relatively short activity."

But the context of phone conversation seems to big a distraction for most motorists.

"We used an eye tracker to try to see what they were looking at while talking on the phone," Strayer said. "The measurements show that they simply aren't picking up information that's right in front of them, whether it's as mundane as a street sign or even a person or child on the side of road."

Interestingly subjects in earlier studies displayed no similar distractions when talking to passengers, or listening to the radio or books on tape. The NHTSA believes that driver distractions of all types are a factor in probably 25 to 30 percent of crashes, but more specific data are unavailable.

"Our findings and those of others are that driving performance can be compromised by using wireless communication devices," Tyson said. "In general there is certainly the potential for deterioration of driving skills if you are talking and driving at the same time—but nobody knows precisely what the impact of cell phones has been."

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