We all know that texting while driving is dangerous, but what about the increasingly popular voice-activated systems that let drivers talk on the phone, text, and even use social media sites behind the wheel?

A new survey found that these hands-free technologies pose serious risks to drivers by diverting their attention — not eyes — from the road. The study, conducted by University of Utah psychology professor David Strayer on behalf of the AAA Foundation for Traffic Safety, found that drivers' mental workload increased when using these systems, slowing their reaction time. This could potentially cause drivers to miss items right in front of them, including stop signs and pedestrians.  

In the study, researchers measured drivers' brainwaves and eye movements to see what happened when they performed different tasks, such as listening to the radio and talking on the phone while behind the wheel. They found that listening to the radio ranked as a "minimal" distraction, while talking on a cell phone, both handheld and hands-free, was a "moderate" risk. On the other hand, the researchers found that using voice-activated systems to send and receive email posed an "extensive" safety risk.

"Increased mental workload and cognitive distractions can lead to a type of tunnel vision or inattention blindness where motorists don't see potential hazards right in front of them," AAA Foundation President and CEO Peter Kissinger, said in a statement.

Based on the research, AAA is urging automakers to limit the use of voice-activated technologies to driving-related activities such as controlling the temperature and windshield wipers. The organization is further recommending car makers disable certain functionalities, such as using social media and email, when a vehicle is in motion. The organization is also using the findings to promote a dialogue with policymakers about the risks of these in-car systems.

"There is a looming public safety crisis ahead with the future proliferation of these in-vehicle technologies," AAA President and CEO Robert L. Darbelnet said in a statement. "It's time to consider limiting new and potentially dangerous mental  distractions built into cars, particularly with the common public misperception that hands-free means risk-free."

The findings are similar to an April report from the Southwest Region University Transportation Center conducted by the Texas A&M Transportation Institute. It tested 43 drivers on a closed course, and found that response times were "significantly delayed" when texting, regardless of whether it was hands free or not.

Meanwhile, not everyone agrees with the AAA's findings about in-car technologies. In a statement, Gary Shapiro, president and CEO of the Consumer Electronics Association, said the study suffers from "a number of methodology flaws, and, as a result, its broad conclusions about voice-to-text technology should be questioned."

The study, Shapiro argued, relied on young drivers in unfamiliar cars who were wearing a helmet and driving on a defined course — not the most natural setting. He referenced a separate study recently completed by Virginia Tech's Transportation Institute on behalf of the National Highway Transportation Safety Administration, which he said found that hands-free, voice-activated devices "constitute no increased safety risks."

The study comes as car makers increasingly integrate these systems into their vehicles. Just last week, for instance, BMW announced that its 2014 lineup will support voice-activated services like Apple's Siri and Samsung's SVoice. And during this week's WWDC, Apple said that its new mobile operating system, iOS 7, will be available in cars.

Editor's Note: Updated on Wednesday at 12:19 with comment from the Consumer Electronics Association.