JACKSONVILLE, Fla. -

Since the debate began over the dangers of texting and driving, auto makers developed hand free technologies that allow drivers to text and talk on the phone without their hands. 

A new study done by AAA shows that the hand free devices many think are making them safe, are actually more distracting than texting and driving. 

The AAA Foundation for Traffic Safety determined that using the radio is the least distracting thing in a car, then talking on a cell phone, then texting while driving.

The study found the most distracting thing to do while driving is using voice activated hands free devices.  

"That's the worst one -- mental distraction. We all think of the physical distraction of a cell phone, but it's not the severest," said AAA's Bill Bishop. 

The study even stunned AAA, who worked with the University of Utah to do the research. 

Researchers hooked sensors up to 150 different drivers to see what distracted them the most. All hands free devices were ruled distracting because while manual texting causes you to look down, hands free devices cause mental distractions. 

The study measured the brain waves, eye movements and other things needed to drive safely. It showed that when drivers had to put thought into operating a hands free device, reaction time slowed down and the field of vision narrowed. 

"The act of holding a cell phone is not the most dangerous part, it is the mental concentration taking focus away from the road that's the problem," said Bishop. 

Channel 4's Crime and Safety analyst, Ken Jefferson, said the devices can be used for talking, texting and even checking Facebook. Jefferson said he's not surprised by the AAA data showing how distracting hands free devices are. 

"Even though it's hands free, you have to concentrate on the button so it's still distracting. There's only one thing to do when driving, that's to concentrate on what's going on on the road," said Jefferson.