Perhaps you've heard the claim that talking on the phone while driving is as risky as driving drunk. Indeed, a driving simulator study found "profound" impairments in both cellphone chatters and in people with a blood alcohol level of 0.08.
But here's the surprising thing: It doesn't seem to make a difference whether drivers are using hand-held phones or hands-free systems. What matters is simply that they are talking with someone outside the car.
Everyone understands the risk of taking your eyes off the road or your hands off the steering wheel, says David Teater, senior director of transportation strategic initiatives for the National Safety Council. But most people don't appreciate the demands of driving on the parts of your brain involved in attention, planning and language, Teater says. Talking on the phone uses some of the same brain space that driving does. So if you're trying to do both, at least one of them is going to suffer.
It's a problem of dual tasks, says David Strayer, a cognitive scientist at the University of Utah. Some dual tasks are no problem, such as walking and chewing gum at the same time. Others are trickier, such as patting your head and rubbing your belly.
A recent study demonstrates that driving while conversing falls squarely in that tricky category. Researchers measured reaction times in young adult drivers exposed to a variety of traffic situations in a driving simulator. Talking on a hand-held cellphone slowed drivers' reactions to seeing a pedestrian enter a crosswalk by 40 percent compared with no conversation. The effect was identical for drivers who talked on a hands-free phone.
How do other distractions compare? Here's the research on some common car activities (besides driving):
- Is talking on the phone more distracting than listening to an audiobook?
A small 2008 study showed that when people listened to an audiobook (in this case, "Dracula"), their performance was the same as when they drove without distraction. But when they carried on a phone conversation with one of the researchers (about hobbies and weekend activities), their performance worsened.
- How distracting is radio?
Strayer partnered with the American Automobile Association to try to measure the relative strength of various cognitive distractions on driving. Study subjects were tested in a driving simulator or a real car while listening to the radio or a book on tape. On a scale of 1 (no distraction) to 5, radio measured 1.2 and the audiobook measured 1.75. The distraction that rated a 5 was to have drivers try to solve math problems and remember a series of words.
- Is talking on the phone more distracting than talking to a passenger?
The cognitive workload for the driver is the same, according to Strayer. In his test, conversing with a passenger rated a 2.3 on the 1-to-5 scale; talking on a hand-held phone, a 2.4; and a hands-free phone, a 2.3. However, having another person in the car generally results in safer driving, because there's often an extra set of eyes on the road. Also, passengers tend to stop talking when the demands of driving increase, Strayer says. "So passenger and cell conversations have different crash risks because the passenger helps out."
Note: Teen passengers don't have the same helpful effect with teen drivers.
- Are there apps for that?
There are apps that when enabled — or when you're traveling over, say, 10 mph — automatically answer calls (and texts) and apps that will read your text messages or e-mails aloud to you. One recent study found that listening to (but not answering) a ringing phone while driving was a distraction.
Despite the data, there's no indication that people are giving up their phone conversations. There are probably plenty of reasons for that, but it's hard to tackle a lack of self-awareness — or worse, hubris. "People notice others driving erratically and talking on their phones, but they don't notice themselves making similar driver errors," Strayer says.
In the past, people would brag about being good drivers even when drunk, Teater says. The same thing is happening now with cellphones. Teater's work was spurred by the death of his 12-year-old son in a cellphone-related car accident. "You never think it will happen to you — until it does," he says.