A new study by the AAA Foundation for Traffic Safety shows that Siri and other voice activated apps pose a risky distraction for drivers. Researchers spent two years measuring the brain activity of drivers. This week Post transportation reporter, Ashley Halsey III took a ride wearing the organization’s brain scanning device. (The Fold/The Washington Post)

Your eyes may be on the road ahead, but if you’re on the phone or using a voice-activated app to send a text message, there’s a disconnect between your eyeballs and your brain.

“Cognitive distraction is something that drivers aren’t aware of, so they may go through a red light or a stop sign and be totally unaware they’ve missed it,” said David L. Strayer, whose research team at the University of Utah conducted a two-year study of driver behavior. “They will tell you ‘I never saw it,’ because their brain was focused elsewhere.”

The study’s most surprising finding is that technology developed to enhance the safety of text messaging while driving is not very effective.

When compared with other diversions inside the car, “interacting with the speech-to-text system was the most cognitively distracting,” the report said. “This clearly suggests that the adoption of voice-based systems in the vehicle may have unintended consequences that adversely affect traffic safety.”

Researchers did a series of controlled studies using driving simulators and on-road tests. For two years, groups of test subjects wore a Medusa-like cap of electrode wires to test how their brains reacted to the rapidly increasing number of distractions that sap the ability of drivers to focus on the road. Each distraction-induced change in brain waves was marked by the computer with a squiggly line on a graph.

Russ Martin of AAA, wearing a EEG-configured skull cap, prepares to drive a research vehicle Tuesday while unveiling research demonstrating that new in-car technologies being marketed by automakers can cause dangerous distractions for drivers. (Jonathan Newton/The Washington Post)

The AAA Foundation for Traffic Safety sponsored the study, which was released Wednesday.

The data were generally consistent with other recent research that can be boiled down to a simple conclusion: The more complicated and absorbing a task, the greater the distraction from the road. The longer it takes to complete — a conversation, a message, setting a GPS destination — the worse it gets.

‘Inattention blindness’

The study also underscored a problem called “inattention blindness,” which translates into layman’s terms as “I see it, but it doesn’t register.” It takes longer for distracted drivers to connect what they see to an appropriate reaction such as braking or swerving to safety.

“It’s very, very powerful,” said the AAA foundation’s president, Peter Kissinger. “The light can register, but the brain is focused on something else.”

Federal data show that distracted driving was a factor in about 10 percent of the fatal accidents nationwide in 2011. In addition to 3,331 deaths — a slight increase from the previous year — 387,000 people were injured in motor vehicle crashes involving a distracted driver.

The AAA foundation’s study is the latest piece in a body of research that has grown exponentially in the five years since Transportation Secretary Ray LaHood elevated a growing public awareness of distracted driving into a national crusade.

Though the findings have not been uniform, the research has established that almost anything that distracts a driver from the task of getting down the road creates a risk.

Proving something most reasonable people would agree on echoes the era when researchers sought to verify that smoking caused cancer. It demonstrates with science the danger of something that has become an immensely popular habit.

Faced with mounting research-based evidence, some drivers may put aside the array of distracting electronic enticements. But the awareness of risk balanced against that desire to chat or text was summed up in a quip at a congressional hearing last year: Everybody wants to keep talking on their cellphone, they just don’t want anybody else on the road to be allowed to.

Drivers have been banned from sending and receiving text messages in 41 states, including Maryland and Virginia, and in the District of Columbia. The District and 11 states — including Maryland but not Virginia — also have prohibited conversations on hand-held cellphones while driving, a restriction that research has shown to be of dubious value.

One of the first studies, conducted in 2008 by Carnegie Mellon University, found that having a phone conversation of any sort distracted a driver — a finding that has been confirmed by several other studies.

The growing body of knowledge has put auto manufacturers in an awkward spot, torn between a desire to produce safe vehicles while still meeting customers’ demand for Internet access, movie screens, GPS innovations, and voice and text communication in their vehicles.

What’s more, as the auto industry seeks to install voice-activated and one-touch applications it views as a marriage of demand and safety, there’s a hitch. While federal regulators can dictate what is installed at the factory, it falls to state legislators to set laws governing hand-held devices.

“As a result, government policy will likely chill innovation and bias drivers toward the use of hand-held devices, rather than integrating devices with ­in-vehicle systems,” Mitch Bainwol, president of the Alliance of Automobile Manufacturers, told a U.S. Senate committee last month. “So if a driver looking for live [mapping] guidance is blocked from doing so while his car is in motion, he may predictably pull out his smartphone, fiddle with the keys while looking down and retrieve the desired mapping guidance.”

The ‘genie’ is out

Strayer said he hoped the strength of the new research would open doors to a joint effort with automakers as new technologies emerge.

“Cellphones are so commonly used that it’s hard to put that genie back into the bottle,” Strayer said. “This is an important time to get with the industry and talk about dealing with emerging technology before that gets out of the bottle, too.”

The AAA foundation briefed other safety agencies on the findings before Wednesday’s release.

“The study is a reminder that distracted driving is a huge challenge,” said Jonathan Adkins of the Governors Highway Safety Association. “States should stay on their current path of banning texting and hand-held cellphones behind the wheel. At the same time, drivers need to be reminded that the safest practice is to not use any type of communications device behind the wheel.”