People who talk on cell phones while they drive are as impaired as drunken drivers, according to researchers at the University of Utah. And it's not a matter of handheld vs. hands-free, either.

"People are as impaired when they drive and talk on a cell phone as they are when they drive intoxicated at the legal blood-alcohol limit" of 0.08 percent, said study co-author Frank Drews, an assistant professor of psychology.

The study by U. psychology professor David Strayer; Dennis Crouch, a research associate professor of pharmacology and toxicology; and Drews was published Thursday in Human Factors: The Journal of the Human Factors and Ergonomics Society.

For the study, 40 participants each "drove" a simulator four times: once undistracted, once using a handheld cell phone, once while on a hands-free cell phone and once while intoxicated to the legal limit from drinking vodka and orange juice.

Results were virtually the same for handheld and hands-free phones. Dialing or digging through a purse to find a ringing phone increased impairment, but the type of phone did not.

Compared with undistracted drivers, cell-phone users in the study drove a little slower, were 9 percent slower to hit the brakes, had 24 percent variation in following distance, were 19 percent slower returning to normal speed after braking and were more apt to crash.

Three of them rear-ended a simulated pace car while talking on cell phones.

The drunken drivers drove more slowly than both undistracted drivers and those on the cell phones, but they were more aggressive, following more closely and twice as likely to brake just four seconds before a crash would have occurred. They also hit their brakes with 23 percent more force. Accident rates, reaction time to a car braking in from of them and getting back up to speed after braking were about the same as that of undistracted drivers.

As for why none of the drunken drivers got into accidents, Drew and Strayer think that because the tests were conducted in the mornings, participants were drunk, but well-rested and in the "up" phase of intoxication. A news release for the study said that 80 percent of all fatal alcohol-related accidents occur between 6 p.m. and 6 a.m., when fatigue compounds the problem. And average blood-alcohol levels in those accidents are twice the legal limit.

Some people don't see why talking on a cell phone is any different from talking to a passenger in a vehicle, Drews said.

The problem, he said, comes from "talking to someone who is not present."

"Assuming it's not a 4-year-old having a temper tantrum in the back," a passenger is also monitoring traffic and modulating conversation to match, as well as pointing out problems, he said.