Psychologists at the University of Utah have published a study claiming that motorists who talk on handheld or hands-free mobile phones are as dangerous as drunken drivers.
"We found that people are as impaired when they drive and talk on a cellphone as they are when they drive intoxicated at the legal blood-alcohol limit of 0.08 per cent, which is the minimum level that defines illegal drunken driving in most US states," said study co-author Frank Drews, an assistant professor of psychology.
"If legislators really want to address driver distraction, they should consider outlawing cellphone use while driving."
Psychology Professor David Strayer, the study's lead author, added: "Just like you put yourself and other people at risk when you drive drunk, you put yourself and others at risk when you use a cellphone and drive. The level of impairment is very similar."
The study reinforced earlier research by Strayer and Drews showing that hands-free mobile phones are just as distracting because the conversation itself, not just the manipulation of a handheld phone, distracts drivers from road conditions.
Each of the study's 40 participants used a PatrolSim driving simulator four times, once with no distractions, once using a handheld phone, once using a hands-free phone and once while intoxicated to the 0.08 per cent blood-alcohol level.
Participants followed a simulated pace car that braked intermittently. Handheld and hands-free mobile phones were found to impair driving with no significant difference in the degree of impairment.
The results "call into question driving regulations that prohibit handheld cellphones and permit hands-free cellphones", according to the researchers.
The study found that, compared with drivers who were not distracted, those who talked on either handheld or hands-free phones drove slightly slower and were nine per cent slower to hit the brakes.
They also displayed 24 per cent more variation in following distance as their attention switched between driving and conversing, were 19 per cent slower to resume normal speed after braking and were more likely to crash.
Drivers drunk at the 0.08 per cent blood-alcohol level were found to drive more slowly than both undistracted drivers and drivers using mobile phones, yet more aggressively.
They followed the pace car more closely, were twice as likely to brake only four seconds before a collision would have occurred, and hit their brakes with 23 per cent more force.
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