Paul Atchley, Kansas University psychology professor

You might be able to compose a text message or an email from your driver’s seat without using your hands. But you can’t do it without using your brain.

That is why a study released last week found that hands-free speech-to-text features can be a big distraction for drivers, even worse than talking on a cell phone, said Paul Atchley, a professor of psychology at Kansas University. The study reported that using those services, increasingly included in new phones and cars as a way to write messages using spoken words, scored at about a 3 on a five-point scale of distraction. That’s compared with less than 2.5 for talking on a cell phone, whether held in the driver’s hand or used with a hands-free feature.

The problem, Atchley said, might be that drivers use the same part of their brain to navigate menus and visualize a message that they use to navigate the road and look at their surroundings.

“It’s no surprise that it’s extremely distracting,” said Atchley, who served as an adviser for the University of Utah researchers who authored the study.

The findings were released last week by the AAA Foundation for Traffic Safety as part of a wide-ranging look at different distractions posed to drivers. And Atchley says it represents some of the most convincing evidence yet that electronic devices can be deadly distractions for drivers, even if they’re not holding them in their hands.

As the study’s authors wrote, “Simply put, hands-free does not mean risk-free.”

Hundreds of studies have demonstrated the distraction caused by electronic devices in cars, including several by Atchley. But few have combined laboratory tests of brain activity with actual on-the-road tests of reaction times, as the AAA one did.

“When all those things point in the same direction, it paints a very convincing case,” Atchley said.

Atchley has researched distracted driving for years and been featured by several national news outlets on the subject of texting or talking while driving, including an appearance on NBC’s “Rock Center with Brian Williams” in January. He and Ruth Ann Atchley — another KU psychologist, and Paul’s wife — both offered assistance with the AAA study before and after it was underway.

His research has shown, he said, that electronic devices impair drivers because they require certain parts of the brain to do multiple things at once.

Though they might seem like simple tasks, talking and listening occupy cognitive real estate in the brain. And dealing with electronic menus and commands without the benefit of looking at a screen can take up even more energy.

“Anyone who’s ever been frustrated with their computer knows how difficult technology can be, even when it seems really simple,” Atchley said.

Falling much lower, between 1 and 2, on the study’s five-point distraction scale were listening to the radio or to books on tape. That kind of passive activity allows drivers to more easily tune out for a few minutes if the road demands their attention, Atchley said.

But the bottom line, he said, is that trying to perform other tasks like talking or texting while driving is just too dangerous a bet.

His advice is the same as it’s been for years: Leave your phone in the trunk when you drive, whether or not you need your hands to use it.

“I always worry when we use technology to solve the problems that technology creates,” Atchley said, “because we have a tendency to make things worse than they were even to begin with.”