When you're driving a car, your eyes are in constant motion—scanning the road for signs, pedestrians, and potential hazards. But if you're talking on a cell phone, watch out: it may give you tunnel vision. You'll find out why in this Science Update.
The risk of thinking while driving. I'm Bob Hirshon and this is Science Update.
Ask someone who routinely chats on a cell phone in their car, and they might insist it doesn't affect their driving. But a new study suggests that doing things that require thinking—like talking on a cell phone—could in fact be stealing your attention away from the road.
Manbir Sodhi of the University of Rhode Island and his colleagues tracked the eye movement of drivers while they performed various cognitive tasks, like memorizing a list or doing a mental calculation. Sodhi says during these tasks, the drivers' range of eye movement narrowed considerably.
If that is indeed attention, then you're not paying as much attention or you're not looking around as much, perhaps not picking up as much detail as you would otherwise.
Sodhi says the research is in its early stages and doesn't yet say whether cell phone use in cars should be limited. But it does highlight some of the issues that might be important in determining policy.
The other thing is this implication that hands-free cell phones are risk-free, and it's only when you're holding the cell phone that you're in trouble. That may not be the case. It may actually be the issue of the conversation that leads to an increase in risk.
Sodhi says the researchers' next study will address these questions in more detail to help assess that risk. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
Ever since cell phones became a part of our national culture, scientists and lay people alike have debated their impact on driving skills. There have already been some warning signs. For example, a 1997 study published in the New England Journal of Medicine found that talking on a cell phone quadrupled the risk of getting into a car accident. A few other studies have also linked cell phone use to poor driving or increased accident rates.
The research conducted by Sodhi, psychology professor Jeffrey Cohen, and colleagues has a couple of key features. First of all, it uses an objective measure of driving skill: the breadth of the visual field that the driver is paying attention to. (Subjects wore a head-mounted tracking device that recorded where their eyes were focused approximately fifty times per second.)
Although the link between having a broad attention field and safe driving is basically an educated guess, it's a reasonable one, since drivers have to process a lot of visual information. And if you're not paying attention to your whole visual field, you could miss something important, like a car that's about to pass you or a child stepping into the street. By studying each driver's visual field, with and without distractions like cell phones, the researchers can eliminate the possibility that people who use cell phones just happen to be bad drivers.
Secondly, by focusing on the mental challenges of using a cell phone, the researchers can respond to the argument that hands-free phones are okay. In this experiment, a simulated cell phone conversation narrowed the drivers' visual field in a manner similar to that of other mental tasks, like remembering lists and making calculations. On the other hand, physical tasks, like adjusting the radio, had a relatively small and brief impact on the driver's visual field. This evidence suggests that it's the mental drain of the cell phone conversation, and not simply holding or operating the cell phone, that impairs driving skills.
Sodhi doesn't think that cell phones should be banned entirely, but he does suggest that their use could be restricted under certain conditions, like bad weather, heavy traffic, or on windy roads. More research should help us understand just how serious the cell phone problem is.
Now try and answer these questions:
- Consider the following statement: "Cell phones don't cause accidents. It's just that people who use cell phones a lot tend to be bad drivers." Does Sondhi's research support this claim? Why or why not?
- Consider the following statement: "People should be allowed to use only hands-free phones when driving." Does Sondhi's research support this claim? Why or why not?
- Design an experiment that would test the effects of cell phones on driving further. What would you measure? How would you measure it? How would you check to see if either of the above arguments was valid?
- Do you think there should be any laws regulating the use of cell phones while driving? How far should they go? What kind of evidence do you feel is necessary to justify these laws?
Why driving while using hands-free cell phones is risky behavior is a recent study that draws conclusions similar to Sondhi's.
The National Safety Council's site called Safety on the Road provides information and resources about staying safe on the road.