TUESDAY, Dec. 2, 2008 (HealthDay News) -- Drivers talking on a cell phone are more distracted and more prone to error than if they were speaking with a friend sitting next to them in the car, a new report finds.
"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," explained study author Frank Drews, an associate professor of psychology at the University of Utah in Salt Lake City.
"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 central piece here is the idea of shared attention," Drews added.
Studies on the dangers of driving while talking on the cell phone abound, but there has been little on talking to a person in a vehicle.
This study, published in the December issue of the Journal of Experimental Psychology: Applied, involved 41 men and women ranging in age from 18 to 26. Each participant was paired with a friend (not a research assistant) and asked to navigate a 24-mile multi-lane stretch of highway with "real" highway conditions represented on a simulator. Participants were asked to talk about a close-call situation they had experienced.
The conversations were intentionally "naturalistic," with participants phoning people who knew them outside of the context of the study, Drews said.
Participants were presented with three scenarios: driver talking on a hands-free cell phone, driver talking with a passenger, or no conversation at all.
Drivers were told to exit the "highway" at a rest area about eight miles from where they started. Partners were also told of the instruction.
"Drivers talking on the cell phone just blew by the exit," Drews said. "The phenomenon here is you talk on the cell phone, realize once you hang up, 'I'm not here.'"
"We had a hard time convincing them that they just didn't perceive [the exit]," he continued. "This is consistent with previous work which showed 'inattention blindness,' a 50 percent impairment of processing visual stimuli" when conversing on a cell phone, Drews said.
Half of the drivers talking on cell phones missed the exit. In contrast, only three of 24 drivers missed the exit when talking with another person sitting next to them.
"The issue with cell phones is a concept called attention," said Dr. Christopher Colenda, the Jean and Thomas McMullin Dean of the Texas A&M Health Science Center College of Medicine. "When you're on the cell phone, it appears as though the process of talking with the cell phone may have an impact on one's attention and ability to visualize what's going on in the environment, because you are focused in on an abstract concept called the telephone."
Another expert agreed, adding that the new data was necessary and important.
"The public and, to a lesser extent, the research community has had this question for some time: What's the difference between talking on a cell phone and talking to a passenger?" said Robert D. Foss, director of the Center for the Study of Young Drivers at the Highway Safety Research Center, at the University of North Carolina. "Conceptually, it's clear there's somebody else in the car, who sees what's going on. This documents with evidence how that plays out."
That's not to say that the proverbial "back seat driver" is necessarily a good thing.
"Probably what you need is someone who is engaged at a medium level," Drews said, not someone who is hyper engaged, pointing out your every error.
The message: Talk to a real person, not on the cell phone, while you're steering and shifting.
Also, if you notice you're talking to someone on a cell phone while they're driving, politely end the conversation.
"You are also responsible for this person's safety," said Drews.
Ultimately, it's the driver who has prime responsibility, however. Talking on a cell phone, "your mind is some place else and not on the road," Colenda said. "When in a car, you're more concerned with the conversation than with the environmental surroundings."
There's more on road safety at the National Safety Council.