Hang up and drive

Think driving while talking on the cellphone is safe as long as you use a headset, as new laws require? Stop yammering and read this article.

By Katharine Mieszkowski

Read more: Politics, News, Neurology, Cell Phones, Cars, Katharine Mieszkowski, Environment & Science

July 25, 2008 | For drivers, the hand-held cellphone is losing its connection. On July 1, bans on holding a phone to your ear while driving went into effect in California and Washington, following the lead of New York, Connecticut, Utah, New Jersey and the District of Columbia.

As the new laws took effect, drivers out West raced to buy up headsets so the gabbing could continue unabated. But as drivers everywhere adjust their talk time to the new laws, one message is getting lost in static: A hands-free phone isn't much safer than a hand-held one when you're behind the wheel.

For years, psychologists who study driving and attention have argued that switching to "hands free" is not a real solution to the hazards caused by yakking on the mobile in the car. "The impairments aren't because your hands aren't on the wheel. It's because your mind isn't on the road," says David Strayer, professor of psychology at the University of Utah, whose research has found driving while talking on a cellphone to be as dangerous as driving drunk.

Now neuroscience is showing your mind literally isn't on the road. The overtaxed driver's poor brain doesn't distinguish between a conversation that takes place on an iPhone or a Bluetooth headset. In both cases, the chatting driver is distracted, putting herself, her passengers, other drivers, bicyclists and pedestrians at risk.

Say there's an 18-wheeler to your right, an R.V. to your left, and suddenly a call comes in from that motormouth client in Kansas City. As the client's voice starts buzzing in your ear, the activity in the parts of your brain keeping your car in your lane declines.

"Forty percent of your attention is drawn away when you're on the phone," says Marcel Just, a psychologist who directs Carnegie Mellon's Center for Cognitive Brain Imaging. That goes for you too, Mr. Multitasker.

In one experiment at the Center for Cognitive Brain Imaging, a test subject lies down inside a magnetic resonance imaging (MRI) machine, and uses a simulator to drive a car along a winding road, like playing a video game. While steering, the driver hears a voice in his earphones making statements, and has to decide whether they're true or false, while continuing to pilot the car. Listening and driving make demands on different parts of the brain. Yet, apparently, there are finite resources to go around. "You have two moderately automatic tasks, executing concurrently and drawing on the same resource pool," explains Just.

When the voice in the headphones starts talking, researchers can see the parts of the brain devoted to driving get distracted. One part of the brain that's important for driving is the parietal lobe, which, for instance, helps a driver make the car's trajectory fit the curvature of the road. "There is much less activity if someone is talking to you, so you take the curve less precisely and less well," says Just. A similar reduction in activity occurs in the visual cortex, which helps a driver analyze how fast things are going by and see what's coming up ahead. When that voice chimes in on the headphones, "your analysis of the visual scene is less thorough. You'd be more likely to miss a sign, or not as quick to read a complex sign," says Just.

But can't you just ignore the voice chatting in your ear when driving conditions get hairy? Apparently not. "Listening to someone talk is a very automatic process and you can't will yourself not to," explains Just. "In another study, we told them [test subjects] to ignore the sentences, but it made very little difference. You have to block your ears. You can't turn off your brain processing." You may think that you're tuning out your husband or BFF on the other end of the phone when road conditions get bad, but it's not that simple.

"It's insidious," says Just. "If you're in a tough driving situation, and someone talks to you, the processing of the language is going to start right away, whether you like it or not."

There's a lot of gabbing going on out there. In 2007, a survey of 1,200 drivers by Nationwide Mutual Insurance Co. found that 73 percent of them talk on the phone while driving. Women and young drivers, ages 16 to 24, are the most likely to drive while chatting on the cell. Last year, the National Highway Traffic Safety Administration reported about 6 percent of drivers were using hand-held cellphones at any moment, based on observational data. That means right now roughly 1 million cars and trucks on the road in the U.S. are being driven by people talking on hand-held phones. NHTSA estimated that about 11 percent of vehicles in the typical daylight moment are being driven by someone on either a hand-held or a hands-free phone.

Since cellphones started taking over the world in the '80s, common sense has told us that people gabbing on them while driving are more likely to get into accidents than those who are not. Now the hard evidence is mounting. In 2005, an Insurance Institute for Highway Safety study found that drivers talking on the cellphone were four times more likely to get in an accident serious enough to injure themselves. That study, based on cellphone records of drivers in Western Australia, confirmed the findings of a similar study on Canadian drivers conducted back in 1997, which found drivers who were on the phone four times more likely to have a crash resulting in property damage. Neither study found any evidence that hands-free phones are safer.

There are about 42,000 traffic fatalities in the United States every year. It's hard to pinpoint just how many crashes involve a driver using a cellphone, since reporting varies. But a 2006 study by the Virginia Tech Transportation Institute and the National Highway Traffic Safety Administration found that driver inattention is implicated in almost 80 percent of crashes and 65 percent of near crashes. The most common form of distraction: the use of cellphones. However, the study found that other forms of distraction -- reaching for a falling Big Gulp, for instance -- were more likely to cause a crash than chatting on the phone.

Yet the rap sheet against driving while chatting just keeps getting longer. A review of 120 studies of cellphones and driving conducted by the Insurance Institute for Highway Safety found that nearly all of the studies reported some impairment of driver performance when on the phone. That includes reacting to hazards more slowly and driving more slowly. Drivers on the phone also tend to be more herky-jerky in the movement of their steering wheel, displaying a lack of control, and have a dangerous habit of weaving out of their lanes.

What's less obvious is the cellphoning driver may literally not see what is right in front of his eyes. Think of all the times your eyes have passed over a sentence in a book and you realized afterward that you had no idea what it said. That's called "inattention blindness," and it can happen while driving, too.

"If you are not paying attention to what your eyes are looking at, you just won't see it," says Strayer. On the phone, incidence of inattention blindness doubles. "Once you get involved in a conversation on the phone, you start paying attention to that, probably creating some kind of image of that conversation, and maybe even actively suppressing the physical environment around you," Strayer says. In eye-tracking studies, researchers have documented drivers' eyes as they pass over a road sign; later, the drivers have no recollection of what the sign said.

Next page: Gabbing while driving makes traffic worse!