On a Tuesday evening two years ago, avid cyclists Christy Kirkwood and Debbie Brown were finishing a 13-mile bike ride in Orange County, Calif., when a driver talking on a cell phone swerved into their bike path, knocking Kirkwood off her bike and throwing her 227 feet. The motorist—who had been travelling at 55 mph—continued a short distance before stopping to see what had happened, says University of Utah psychology professor David Strayer, PhD, who served as a consultant on the case.
"The driver thought he'd hit a deer," Strayer recalls.
Kirkwood died from her injuries. Unfortunately, such tragedies have become all too common. In fact, two epidemiological studies—one published in 1997 in The New England Journal of Medicine (Vol. 336, No. 7), and another published online in 2005 in the British medical journal BMJ—report that talking on the cell phone while driving increases your risk of being in an accident fourfold—an alarming statistic given that 84 percent of Americans own cell phones, according to the Cellular Telecommunications and Internet Association.
In addition, a new report from the AAA Foundation for Traffic Safety finds that more than half of U.S. drivers admit to using a cell phone while driving, at least occasionally. The Human Factors and Ergonomics Society estimates that 2,600 deaths and 330,000 injuries in the United States result each year from driver cell phone use.
Of course, Americans are increasingly using personal digital assistants and other devices that undermine their attention, as well. Last fall, 25 people died and 113 were injured when a commuter train collided head-on with a freight train outside Los Angeles. A National Transportation Safety Board investigation found that text messaging may have played a role: Cell phone records showed the train's engineer had sent a text message 22 seconds before the crash. Last year, Americans sent more than 600 billion text messages—10 times the number they sent three years ago. And 41 percent of us have logged onto the Internet outside our homes or offices, either with a wireless laptop connection or a handheld device, finds a 2007 Pew Internet Project survey.
The problem doesn't just rest with drivers: A 2007 study in Accident Analysis and Prevention (Vol. 39, No. 1) by University of South Wales psychologist Julie Hatfield, PhD, found that female pedestrians talking on mobile phones were less likely to look for traffic before stepping into the street and crossed the road more slowly, increasing their risk of colliding with a vehicle.
"As technology and interruption become more and more prevalent, the negative consequences of not paying attention become more pronounced," says Strayer.
With their knowledge of human behavior and cognition, Strayer and other psychologists are exploring the causes of distraction and working to raise awareness of its danger. At the same time, scientists are designing technology that isn't as mentally demanding.
Most people have no problem watching television as they jog on a treadmill or chewing gum while they walk. These are largely effortless tasks that require little sustained attention or thinking. And that may be why many believe they can drive and do any number of secondary tasks as well—from eating or applying makeup to scanning for a song on their MP3 players or talking on cell phones.
But cognitive scientists' research shows the brain has limited bandwidth. Research by psychologists Marcel Just, PhD, and Tim Keller, PhD, of the Center for Cognitive Brain Imaging at Carnegie Mellon University, examined brain activity while participants performed two high-level tasks—responding whether auditorily presented sentences were true or false and mentally rotating three-dimensional objects—both separately and then concurrently. Their findings, published in 2001 in NeuroImage (Vol. 14, No. 2), suggest when performing the actions together, brain activation, primarily in the temporal and parietal areas of the cortex, was substantially less than the sum of the activation when participants performed the two tasks alone, even though the tasks drew on different brain regions.
This suggests, Just says, that dual-tasking compels the brain to pull from some shared, limited resource, slowing reaction time.
Another new study he led, published last year in Brain Research (Vol. 1, No. 205), examines how this central bottleneck plays out when we're driving. Researchers collected fMRI images of 29 undergraduates as they simulated steering a vehicle along a curving road, either undisturbed or while listening to spoken sentences that they judged as true or false. They found that the listening task reduced driving-related brain activity—the spatial processing that takes place in the parietal lobe—by almost 40 percent.
Just says he expects that such reduction in brain activity occurs no matter where the speech comes from, be it a cell phone, fellow passenger or even a talk radio show.
"Processing spoken language is especially insidious in cars because it's automatic," Just says. "When we ask subjects to ignore what's being said, you can still see the activation associated with the processing of that language."
Meanwhile, new research in the December Journal of Experimental Psychology: Applied (Vol. 14, No. 4) shows that cell phone conversations are especially detrimental to driving. The researchers found that cell phone users are more likely to drift out of their lanes and miss their exits than people having in-person conversations. Interestingly, conversations with passengers barely affected any of these three measures. In fact, most passengers took an active role in supporting the driver, often by discussing surrounding traffic. This shared situational awareness may help drivers synchronize an in-vehicle conversation with the processing demands of driving, says study author Frank Drews, PhD, a University of Utah psychology professor.
"If you look at the crash risk, you're actually somewhat less likely to be involved in an accident if you have a passenger than if you're driving by yourself," says Strayer, who collaborated with Drews and colleague Monisha Pasupathi, PhD, on the study.
Human factors experts at the Virginia Tech Transportation Institute (VTTI) have gone a step further to explore how driver inattention leads to collisions. With support from the National Highway Traffic Safety Administration, Virginia Tech researchers tracked driver behavior in 100 vehicles equipped with video and sensor devices for one year. During that time, the vehicles traveled nearly 2 million miles and were involved in 69 crashes and 761 near-crashes. Researchers found that nearly 80 percent of crashes and 65 percent of near-crashes involved driver inattention up to three seconds before the event.
"We were actually able to physically see drivers who were talking on their cell phones, dialing, applying makeup and all the other secondary tasks, and there was no question when it was a contributing factor in the occurrence of a crash," says Charlie Klauer, PhD, a senior research associate at VTTI.
The group recently completed a similar study with 40 teen drivers, who are often the most inexperienced and the earliest adopters of new technologies. Klauer expects the results will show that teens have trouble adapting their behaviors in hazardous driving situations and that distractive devices play an even larger role in teen accidents.
New research also establishes the risks of other technologies:
Drews's as-yet-unpublished research on text messaging suggests the activity may make motorists even more inattentive: A driver's chance of getting into an accident increases sixfold when he is texting.
Research by Susan Chisholm, PhD, of the Cognitive Ergonomics Research Lab at the University of Calgary, shows the dangers of mixing digital music players and driving. Her study of 19 drivers age 18 to 22 shows that collisions nearly doubled while people performed such iPod tasks as scanning to find a particular song (Accident Analysis and Prevention, Vol. 40, No. 2).
Research by Hatfield and colleague Timothy Chamberlain reveals that in-car TV screens distract drivers of neighboring cars, resulting in reduced reaction times and impaired lane-keeping.
There's even concern that car navigation systems may distract the very drivers they are trying to help. In a simulated-driving study published in Human Factors (Vol. 46, No. 4), researchers found that when motorists entered information into a touch-screen navigation system, they drove outside lane boundaries 21 percent of the time, as compared with undistracted drivers who strayed only 1.5 percent of the time. Even those providing an address to a speech-recognition system left their lanes 6 percent of the time.
Among the ways psychologists are seeking to improve driver safety is developing technological interventions that reduce a driver's workload. Backed by his own research (Accident Analysis and Prevention, Vol. 40, No. 2), John D. Lee, PhD, director of human factors research at the University of Iowa's National Advanced Driving Simulator, has found that providing real-time and post-drive feedback to drivers on how well they're doing behind the wheel will help mitigate distraction. With the help of eye-tracking technology, Lee's team has designed an alert system that monitors what motorists are looking at and warns them when their eyes veer away from the road for more than two seconds.
Meanwhile, at the University of Michigan's Transportation Research Institute, scientists have developed a tool to measure traffic conditions, road surface and visibility. Taking into account the driver's experience level, the equipment prevents the driver from receiving phone calls or entering an address into a navigation system when conditions get dangerous.
Early versions of both devices are already in place in some Saabs and Volvos. University of Michigan psychologist Paul Green, PhD, is hopeful that these types of countermeasures will help get motorists' attention back on the road.
"It isn't the solution, it's just a piece of the solution, but it's an interesting one," Green says.
Psychologists are also working to raise awareness about the dangers of distracted driving.
The VTTI researchers, for example, are working with nonprofit organizations, including the Bedford County Combined Accident Reduction Effort, to get the word out about the effects of distracted driving. Thanks to their efforts, the Bedford County driver's education program encourages parents and teens to use driving contracts that limit cell phone and MP3 player use while driving.
In a national effort, in April the National Highway Traffic Safety Administration published "Driver Distraction: A Review of the Current State of Knowledge," which summarizes research on inattentive driving and examines ways to address the problem through public awareness and legislation. In response to the report, APA Chief Executive Officer Norman B. Anderson, PhD, sent a letter to NHTSA urging the organization to identify areas in need of further research and make recommendations for public outreach efforts.
"Distracted driving is a public health hazard without age barriers that is often misunderstood by not only the public but also by both state and local policymakers," Anderson wrote.
Just agrees, noting that a deeper appreciation for the cognitive strain secondary tasks put on our ability to drive or cross the road might help reduce fatalities.
"I think people are unaware of the fact that using a cell phone has such a massive impact on their performance," he says.
Research that compares and quantifies driver distraction could help. One such study, published in Human Factors (Vol. 48, No. 2), suggests that a driver talking on a cell phone is more impaired than one with a blood alcohol level exceeding 0.08.
"Most people wouldn't think of getting in a car with someone who's been drinking, but they don't have a big problem getting into a car with someone who's using their cell phone," Just says.
Yet efforts to reduce driving while intoxicated went beyond public awareness and increasingly included hefty fines, says Anne McCartt, PhD, vice president of research at the Insurance Institute for Highway Safety. In the case of inattentive drivers, legislation limiting cell phone use may prove effective, she notes. At Monitor press time, no state had yet banned all cell phone use by every driver, but 17 states and the District of Columbia do prohibit novice drivers from using cell phones, and six states and D.C. have outlawed drivers from using hand-held phones. Seven states bar text messaging, and nine prohibit teens from the activity.
McCartt admits, however, that these laws either are often not enforced enough to change driver behavior, or they exempt hands-free devices without taking into account the research that shows hands-free devices are just as dangerous as hand-held ones. In fact, some psychologists say hands-free exemptions may encourage motorists originally disinclined to use a cell phone while driving to view the activity as safe.
"To some extent, these laws that didn't pay attention to the science may end up actually making the roads a little less safe," Strayer says.
William C. Howell, PhD, chair of the Human Factors and Ergonomics Society's government relations committee, agrees, noting that policymakers may be passing laws to assure the public that they're curing the problem while they are actually misdiagnosing it.
"Not only do we have a bunch of virtually unenforceable and uninformed laws but a false sense that they represent a fix," he says. "Sure, we need to keep up the pressure for more research, but we know enough about how attention works already to guide strategies for addressing the problem in much more promising directions. In other words, our society should be using what's already known more judiciously in dealing with this problem while doing the research necessary to find even more effective approaches."
One way to do this may be to target driver distraction campaigns toward those on the other end of the phone line, says Drews.
"Cell phone conversations take two people," he says. "We need to convince those callers who know that the person they're talking to is driving to ask the driver to pull over or to call them back later."
He says disseminating this message more broadly to the public might help solve the problem more effectively—and may be more economical—than new vehicle technologies or additional legislation.
"It doesn't cost anything," he notes. "They just have to hang up."
Psychologists' research is also informing legislation on the hazards of using these technological devices even when people are not behind the wheel. In 2007, when two pedestrians were killed after being hit while listening to iPods, New York state senator Carl Kruger proposed legislation that would ban the use of handheld devices such as BlackBerrys, iPods and portable video games while crossing streets in major New York cities. Under the bill, pedestrians and bicyclists caught using any kind of electronic device while crossing a street would be hit with a $100 fine. In July, Illinois became the first state to consider a ban on using a cell phone while crossing a street. Neither bill has passed, but several organizations have moved to make pedestrians more aware of the dangers of technologies that divert our attention.
In July, the American College of Emergency Physicians Foundation warned against cell phone use while driving, bicycling, rollerblading or walking, saying they'd noticed a rise in injuries and deaths related to sending texts while engaging in these activities. Also last year, the nonprofit London-based organization Living Streets installed padded lampposts on a busy street in London as part of a safety campaign targeting distracted pedestrians. The move was prompted by a United Kingdom phone survey of 68,000 that found that one in 10 have been injured while walking and texting on their cell phone.
Just says he's not surprised that the use of cell phones while walking has prompted concern.
"Our research extends to other tasks besides driving," Just says. "The reason walking is different, though, is because when you're driving, the person you're most likely to hurt is someone other than yourself."
Psychologists say they hope work like this leads to increased motorist and pedestrian safety, just as campaigns and laws to encourage seat belt use—which has increased every year since NHTSA began collecting data in 1994—led to a steady decrease in passenger fatalities.