From The Ergoweb® Learning Center

Study: More Dangerous to Drive on Cell Phone than Chat with Passenger

Researchers at the University of Utah (UU) startled the world in 2006 when then showed that using a cell phone behind the wheel and driving with a 0.08 percent blood alcohol – rated as drunken driving in most states – are comparably hazardous. Their latest findings might be less startling, but they add to the evidence that drivers under the influence of a cell phone are a menace to themselves, their passengers and other road users.

The new research shows that drivers are more impaired by talking on a cell phone than by conversing with a passenger in an automobile.  The study by UU psychologists Frank Drews, David Strayer and Monisha Pasupathi, was published in the December issue of the Journal of Experimental Psychology: Applied. It showed that while on a cell phone drivers are more likely to drift from their lane or miss their exit than if they were speaking with a friend sitting next to them in the car, according to a UU news release about the study.
Previous studies by professors Strayer and Drews, featured in The Ergonomics Report™ and Ergonomics Today™,  have found that hands-free cell phones are just as distracting as handheld models because the conversation is the biggest distraction. They also have shown that when young adults talk on cell phones while driving, their reaction times become as slow as reaction times for senior citizens,

Dr. Strayer says he often is asked about the distraction caused by conversations with passengers versus people on the other end of a cell phone, "because in both cases you have a conversation." But if you take a look at the data, he said in the news release, “it turns out that a driver conversing with a passenger is not as impaired a driver talking on a cell phone. You see bigger lane deviations for someone talking on a cell phone compared with a driver talking to a passenger. You also find when there is a passenger in the car, almost everyone takes the exit. But half the people talking on the cell phone fail to take the exit."

"The difference between a cell phone conversation and passenger conversation is due to the fact that the passenger is in the vehicle and knows what the traffic conditions are like,” he explained,  “and they help the driver by reminding them of where to take an exit and pointing out hazards."

"We think it is basically a process of joint attention, so when you have a person sitting next to you who is experienced as a driver, that person actually understands something about traffic, supports you actively in dealing with traffic," added Dr. Drews, the lead author of the study. "You get very supportive behavior that shows not only in gestures but in switching the conversation . . . to what is happening in the driving environment," he said. 

The authors said the problems could have stemmed from inattention "blindness," or insufficient processing of information from the driving environment. Cell-phone users may also have found it harder to hold in working memory the intent to exit at the rest area.

Source: University of Utah