As the new laws took effect, drivers 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. 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.
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.
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 a road sign; later, the drivers have no recollection of what the sign said.
Driving while chatting isn't just hazardous, it can cause more traffic. A recent study by Strayer and colleagues found that drivers who are stuck in traffic can in part blame other drivers who are gabbing on the phone for the holdup. Or, as Strayer put it: "That SOB on the cellphone is slowing you down, and making you late." That's because drivers on cellphones drive more slowly and are less likely to pass slow-moving vehicles. If about 10 percent of the people driving during rush hour are using a cellphone, the net effect is that the commute may be 10 percent slower.
As long as the Model-T has been on the road, people have been conversing with the passengers in their vehicles, if only to scream at the pesky kids, "Shut up! I'm trying to drive!" But there's a difference between talking to somebody in the car and on the phone. Most passengers in the car adjust their conversation to what's happening on the road, quieting down when traffic gets hectic or even pointing out hazards up ahead, acting as a second set of eyes. The person on the other end of a cellphone call might not know you're driving, much less be aware of the road conditions. "The difficulty is that the party on the other line has no sense of your driving situation and just yaks, and the driver elects to do it, too," explains Paul Allan Green, research professor at the University of Michigan Transportation Research Institute, where he leads the Driver Interface Group.
Inside a car, there can be natural lulls in the conversation of 20 or 30 seconds, and there is no awkwardness associated with it. Not so on the cellphone call, where there's more social pressure on the driver to hold up his or her end of the conversation, if only to assure the other party that the call hasn't been dropped. "There is all sorts of social pressure to continue the conversation and not break it off," says Green. When a driver does stop talking to focus on the road, his caller is likely to ask, "Hey, can you hear me? Are you there?" The caller tries "to reengage the driver at the wrong time," says Strayer.
Further, researchers find that people tend to be more chatty in a cell conversation than an in-car one. "Cellphone conversations are more intense than in-car conversation," says Paul Atchley, professor of psychology at the University of Kansas. That intensity can be measured. Researchers in England studied drivers' conversations with both passengers and callers. They found that people used a higher number of words per minute on cellphone conversations.
In the end, car passengers just have more skin in the game. "People in the car have their own safety at risk," says Atchley. "It's to their advantage to not put the driver in the dangerous situation, so we as passengers tend to edit ourselves pretty effectively."
Researchers doubt that banning hand-held phones gets to the root of the problem: the conversation. Sure, it's safer to have both hands on the wheel, but no one is passing laws banning stick shifts. Atchley believes that the new cellphone laws may be counterproductive, instilling a false sense of security, since they may lull drivers into thinking that gabbing on the hands-free phone is just fine.
"People are led to believe that as long as they have their Bluetooth wireless headset they're safe, when in fact they're probably at more risk, because now that they think that they're safe they're probably going to make more calls and be at risk for even greater periods of time," says Atchley. On the other hand, not everyone who strives to follow the new laws will bother to get a hands-free phone. "If people really don't use their cellphone because they don't have a hands-free unit, then that could actually be a good thing," Strayer says.
Researchers are already studying the impact of hands-free laws, trying to predict what the new laws will (and won't) accomplish. Jed Kolko, an economist with the Public Policy Institute of California, studied the fatality rates in New Jersey, New York, Connecticut and D.C. before and after their hand-hell cellphone bans went into effect, also comparing traffic fatalities with those in states that did not implement bans. Based on his data, Kolko predicts that California will see 300 fewer traffic fatalities per year, during times of adverse driving conditions, like bad weather, because of the new hands-free law. (California has over 4,000 traffic fatalities annually.)
Even so, it may take decades for public concern about the problem to catch up with the ubiquity of cellphone use behind the wheel. As Atchley notes, the first drunken-driving law went on the books in 1917, yet it wasn't until the 1980s that a grass-roots movement, spearheaded by the likes of Mothers Against Drunk Driving and Students Against Driving Drunk, led to wide enforcement and tougher laws. It will likely take a similar national mobilization of the aggrieved family members of people killed or maimed by drivers talking on cellphones to raise public awareness of just how dangerous it is.
As for the researchers who study driving and talking on the phone, aren't they tempted to make a few calls when they're stuck in traffic, just like the rest of us? Maybe so, says Green from the University of Michigan Transportation Institute. But when he's driving, "my phone is off," he says.
A version of this story first appeared on Salon.com.