NORTH HOLLYWOOD ( — A new study released by the American Automobile Association (AAA) Thursday shows hands-free technology can mentally distract drivers even when they are focused on the road.

According to the AAA Foundation for Traffic Safety, researchers found potentially unsafe mental conditions could occur for as long as 27 seconds after a driver sends text messages using voice commands, changes music or makes a phone call.

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“The lasting effects of mental distraction pose a hidden and pervasive danger that would likely come as a surprise to most drivers,” explained Peter Kissinger, President and CEO of the AAA Foundation for Traffic Safety. “The results indicate that motorists could miss stop signs, pedestrians and other vehicles while the mind is readjusting to the task of driving.”

Researchers compared 10 2015 vehicles and three types of smart phones to rate levels of distraction based on a five-point scale.

Category one represented a mild level of distraction such as listening to the radio or an audio book; category two marked similar distraction to talking on the phone; category three portrayed sending voice-activated text messages; category four represented updating social media accounts while driving; category five detailed a maximum level of distraction, according to the study.

Any test results showing higher than a category two was considered to be potentially dangerous while driving.

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“Drivers should use caution while using voice-activated systems even at seemingly safe moments when there is a lull in traffic or the car is stopped at an intersection,” said Marshall Doney, AAA’s President and CEO. “The reality is that mental distractions persist and can affect driver attention even after the light turns green.”

Researchers found that a Chevy Equinox performed the best, with a rating of 2.4, while a Mazda 6 ranked the worst at a 4.6 level.

According to the study, Google Now performed best rating 3.0, followed by Apple Siri ranking at 3.4 and Microsoft Cortana at 3.8.

Overall, findings showed the systems that performed best had fewer errors for the most part, were relatively easy to use and required less task time.

Drivers who used their phones to send text messages had a significant increased level of distraction.

“The massive increase in voice-activated technologies in cars and phones represents a growing safety problem for drivers,” added Doney. “We are concerned that these new systems may invite driver distraction, even as overwhelming scientific evidence concludes that hands-free is not risk free.”

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Dr. David Strayer and Dr. Joel Cooper of the University of Utah conducted research for this study.