Two new studies, released Tuesday by the AAA Foundation for Traffic Safety and the University of Utah, have found that voice-activated smartphones and dashboard infotainment systems may be contributing to the problem of distracted-driving. However, David Strayer, the University of Utah psychology professor who led the two studies, said researchers have found that some systems can be more user friendly than others. “The good news is that really well-designed systems offer us the possibility to interact in ways that aren’t so distracting.

During testing, the systems let the drivers do things like tune the radio, send a text message, or make a phone call while keeping their eyes on the road and their hands on the wheel. Many of the systems required more concentration from drivers rather than less. The studies contradict claims by automakers, who have been pitching the voice systems to car buyers as a way they can safely enjoy social media and connectivity.

Tests were performed by university students and other volunteers in three settings: a laboratory, a driving simulator and while driving through a Salt Lake City neighborhood. The systems were graded on a scale of 1 to 5, with 1 being no distraction and 5 comparable to doing complex math problems.

One study examined infotainment systems in some of the most common auto brands on the road: Chevrolet, Chrysler, Ford, Hyundai and Mercedes. The second study tested the Apple iPhone’s Siri voice system to use phone features without handling or looking at the phone. Apple’s Siri received the worst rating, 4.14. Twice test drivers using Siri in a driving simulator rear-ended another car. Chevrolet’s MyLink received the worst rating, 3.7, among the infotainment systems.

The worst ratings came from errors, even though voice commands were clear and distinct. “When these systems become more complex, like sending text messages or posting to Facebook, it pushes the workloads to pretty high levels and may be dangerous while driving,” Strayer said.

The National Highway Traffic Safety Administration, which regulates vehicle safety, has issued guidelines to, but the guidelines are voluntary, since the infotainment systems are unregulated.

Two of the infotainment systems were rated relatively low for distraction. Toyota’s Entune received a 1.7, the distraction equivalent of listening to an audiobook, and Hyundai’s Blue Lin Telematic System received a 2.2.