Talking on a hands-free cell phone while driving may not be much safer than talking on a hand-held phone, according to a new study in the Journal of Experimental Psychology: Applied (Vol. 9, No. 1).
The study could have important implications for how cell phones are used, the researchers say. About 85 percent of the more than 135 million Americans who own cell phones say they use them while driving.
University of Utah psychologist David Strayer, PhD, and his collaborators used a high-fidelity driving simulator to study the impact of cell phone use on the driving performance of 110 undergraduates. A member of the research team engaged the undergraduates in hands-free cell phone conversations while they drove along computer-simulated freeways and city roads.
The researchers found that the conversations slowed drivers' reaction times and increased their risk of crashing into the simulated cars in front of them, apparently by misdirecting their attention. They also found that when participants were in the "cell phone zone," their ability to remember billboards along the side of the road was significantly worse than when they were not on the phone, even though they looked at the roadway signs just as often.
The effect, known as inattention blindness, may explain why talking on a hands-free cell phone can impair driving, says Strayer. "The conversation is drawing attention away from driving and redirecting it towards the virtual reality of the conversation," he explains.
The findings suggest that laws that ban the use of hand-held cell phones while driving, such as the one enacted by New York state in 2001, may not be effective at reducing cell phone-related accidents.
"The legislation that's been enacted says, 'Let's prohibit hand-held cell phones and permit people to use hands-free phones while driving,'" says Strayer. "Our study shows that a big component of the impairment is from cognitive distraction, and this distraction is the same for both hand-held and hands-free phones."