Cell Phones Can "Blind" Drivers

Jan. 28, 2003 - You can shout at the driver talking on the cell phone to "watch the road", but it might not make a difference. Drivers who talk on the phone may be "blinded" by their conversations and are more likely to cause an accident -- even if they use a hands-free cell phone.

A new study shows that telephone chatting causes a unique type of "inattention blindness" that slows drivers' reaction times and may even contribute to traffic jams and air pollution.

Researchers say even when drivers are directing their gaze at objects in front of them on the road and elsewhere, they may fail to "see" them clearly because their attention is directed elsewhere.

"Phone conversations impair driving performance by withdrawing attention from the visual scene, yielding a form of inattention blindness," writes researcher David Strayer, a psychologist at the University of Utah, and colleagues. Their study appears in the March issue of the Journal of Experimental Psychology: Applied.

The researchers say the results help explain the findings of their 2001 study, which found that users of hands-free and hand-held cell phones suffer from equal impairment when driving. That widely publicized study found both types of cell phone users miss more traffic signals and are slower to react to signals than other motorists who do not use cell phones.

In this study, researchers conducted four different experiments on a group of 110 University of Utah students to measure the effect of hands-free cell phone use on attention and visual processing skills.

In the first test, participants drove a driver training simulator similar to those used by law enforcement agencies while periodically conversing on a hands-free cell phone with another student. They drove 40 miles on a simulated freeway in both light and heavy traffic conditions, and researchers measured the drivers' responses to the brake lights of a pace car in front of them.

Although no accidents occurred in light traffic or among drivers not using cell phones, three drivers rear-ended the car in front of them while talking on a cell phone in heavy traffic.

The study also found that drivers who talked on a cell phone reacted sluggishly and compensated by increasing the distance between themselves and the car in front of them. Researchers say these effects became more pronounced as traffic grew heavier, which suggests that cell phone use may increase traffic congestion as well as even road rage and air pollution.

Other tests measured how cell phone use affected each driver's attention and processing of information by tracking their eye movements and testing their ability to recall billboards encountered. The study found that even when a cell phone user looked directly at a billboard, he or she was less likely to remember it than drivers who did not use a phone.