A study from the American Automobile Association (AAA) has found that using hands-free texting features is actually more dangerous for drivers than making handheld phone calls. The group notes that even while texting through systems such as Ford Sync and Toyota Entune, drivers were found to be more distracted than while listening to music, talking with a passenger and making a phone call. Drivers who used hands-free technology were found to have a slower reaction time and compromised brain functions, which could potentially result in drivers not seeing items right in front of them such as stop signs and pedestrians. As cars become smarter and more connected, the AAA is calling for the government to set limitations on “new and potentially dangerous mental distractions built into cars.”

“The agency is aware of the new research AAA released today and will review its findings,” the National Highway Traffic Safety Administration said in a statement to Businessweek. “NHTSA continues to work closely with our safety partners to capture the full safety impact distraction poses to motorists and all road users.”

For the study, the AAA had drivers in their 20s and 30s, all of whom had clean driving records, perform a variety of tasks such as listening to the radio and talking on the phone. Researchers used special sensors mounted on a driver’s head to measure their reaction time and the levels of mental distraction they experienced while performing each task. Listening to the radio was found to be the least distracting and posed minimal risk, while both handheld and hands-free calling had a moderate risk. The advocacy group found that using voice-activated commands and features posed an extensive risk to both drivers and pedestrians.

“These findings reinforce previous research that hands-free is not risk-free,” said AAA Foundation President and CEO Peter Kissinger. “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.”