Feb. 3, 2005 - Talking on a cell phone while driving can turn a normally attentive young driver into a virtual senior citizen behind the wheel, according to a new study.
"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. It's like instantly aging a large number of drivers," says researcher David Strayer, a psychology professor at the University of Utah, in a news release.
The study also showed that drivers who talked on cell phones, regardless of their age, took longer to regain speed after hitting the brakes and slowed the normal flow of traffic, which will come as no surprise to anyone who has ever been stuck behind a sluggish driver chatting away on a cell phone.
The results of the study appear in this winter's issue of Human Factors, the quarterly journal of the Human Factors and Ergonomics Society.
In the study, researchers compared the driving skills of 20 older adults (ages 65 to 74) and 20 younger adults (ages 18 to 25) with normal vision and a driver's license in a high-tech driving simulator. The participants used the steering wheel, dashboard instruments, and brake and gas pedals from a Ford Crown Victoria sedan and were surrounded by three screens showing freeway scenes and traffic.
Each driver drove four simulated 10-mile freeway trips, talking on a hands-free cell phone with a research assistant for half the trips and without talking for the other half. A pace car intermittently hit its brakes as it appeared in front of the participants, and if the driver failed to hit their own brakes, they would eventually rear-end the pace car.
The results showed that drivers who talked on cell phones, of any age, were 18% slower in hitting their brakes than drivers who didn't use cell phones. The drivers chatting on cell phones also had a 12% greater following distance, which researchers say is an effort to compensate for paying less attention to road conditions, and took 17% longer to regain the speed they lost when they hit the brakes.
When young drivers used cell phones, researchers found the reaction time in hitting the brakes slowed to match that of elderly drivers who did not talk on cell phones, an average of about nine-tenths of a second. When not talking on cell phones, young motorists hit the brakes within an average of almost eight-tenths of a second.
Researchers say that difference may seem small, but it represents a 17% slower reaction time.
Strayer says other studies have shown that that much of a decrease in reaction time increases both the likelihood and severity of accidents.
Four of the participants rear-ended the pace car while talking on a cell phone in the simulator, and two rear-ended the pace car while not talking on a cell phone. Researchers say there were too few collisions in this study to conduct a statistical analysis.
But Strayer says twice as many rear-end collisions occurred among cell phone users than non-cell phone users.
"Older drivers were slightly less likely to get into accidents than younger drivers," says Strayer. "Why? They tend to have a greater following distance. Their reactions are impaired, but they are driving so cautiously they were less likely to smash into somebody," although in real life, "older drivers are significantly more likely to be rear-ended" because of their slow speed.
The study showed that when elderly drivers used cell phones, their reaction times got worse but not as bad as had been expected.
Researchers say previous research has suggested that older people might be more severely impaired if they used a cell phone while driving because it would be more difficult for them to divide their attention between the road and the conversation.
But the study showed that older adults don't suffer any more than younger adults when talking on a cell phone while driving, perhaps because they have more experience driving and take fewer risks, says Strayer.