By Maggie Fox, Health and Science Correspondent
WASHINGTON, Jan 27 (Reuters) - Drivers who use a cellular telephone, even with a "hands-free" device, suffer from a kind of tunnel vision that endangers themselves and others, U.S. researchers said on Monday.
Legislation that seeks to make mobile telephone use by drivers safer by mandating the use of a hands-free device may be providing a false sense of security, they warned.
New York is the only U.S. state that requires the use of the devices for mobile telephone conversations while driving, but 30 others have been considering similar laws, as has the Canadian province of Newfoundland.
"Sometimes you have to actually do the silly study that shows the obvious," David Strayer, an associate professor of psychology at the University of Utah, who led the study, said in a telephone interview.
Strayer, whose team has done a series of studies on cellphone use while driving, set up a driving simulator and put 20 volunteers in it. Sometimes they used a cellphone and sometimes they did not. Their reaction time, driving style and performance were monitored.
Writing in the March issue of the Journal of Experimental Psychology: Applied, Strayer's group said use of a cellphone clearly distracted the drivers.
The finding adds to a series of similar studies - most notably a 1997 New England Journal of Medicine report that found talking on a phone while driving quadrupled the risk of accident.
"People, when on a cellphone compared to when they weren't, overall their reactions were slower," Strayer said. "They got into more rear-end collisions. They just kind of had a sluggish style that was unresponsive to unpredictable events like a car breaking down in front of them, a light changing and things like that."
There was no difference, Strayer said, between using a hands-free or a hand-held cellphone.
IMPAIRED EITHER WAY
"You were impaired in both cases," he said. "That suggests to us that whatever legislation may be put into place saying you can do one but not the other ... might send the wrong message and give people a false sense of security."
Perhaps even more disturbing, Strayer said, was the finding that the volunteers did not realize they were driving badly.
"We asked people afterward how they felt they performed and they usually felt they performed without impairment and, in some cases, thought they drove better when on the cellphones," Strayer said.
"It is like studies that show 90 percent of people think they are better-than-average drivers. Forty percent of them are wrong."
Strayer wanted to know why talking on a cellphone had such a profound effect on drivers, so his team set up a second experiment.
"We used an eye tracker -- a really precise device that allows us to see where someone is looking," he said.
They found that while the drivers looked at objects, in this case billboards, if they had been talking on a cellphone at the time they could not remember having seen them.
"There is a kind of a tunnel vision -- you aren't processing the peripheral information as well," Strayer said. "Even though your eyes are looking right at something, when you are on the cellphone, you are not as likely to see it."
This included road signs, other vehicles and traffic lights. "This is a variant of something called inattention blindness," Strayer said.
Tests showed this kind of inattention did not affect drivers who were listening to music, to audio books or talking with a passenger in the car.