Hands-free, voice-controlled infotainment systems in cars can distract drivers, scientists have found.
University of Utah researchers found that voice-controlled automobile infotainment systems can distract people behind the wheel, although it is possible to design them to be safer.
Researchers found that the voice-based systems that were more distracting were that way because they were too complex, mentally demanding, difficult to use and often inaccurate at recognising voice commands.
"Even though your car may be configured to support social media, texting and phone calls, it doesn't mean it is safe to do so," said University of Utah psychology professor and study leader David Strayer.
Researchers found that using Apple iPhone's Siri to send and receive texts, post to Facebook and Twitter and use a calendar was more distracting than any other voice-activated technology - even when it was modified for use as a hands-free, eyes-free device so drivers kept their hands on the wheel and eyes on the road.
The research, sponsored by the AAA Foundation for Traffic Safety, involved 162 University of Utah students and other volunteers.
The participants performed a series of tasks (such as calling, texting, tuning the radio) using various voice-based, interactive technologies while they looked at a computer screen, operated a driving simulator and drove real cars on a loop through Salt Lake City's Avenues district.
The findings follow a 2013 AAA-University of Utah study that showed using hands-free devices to talk, text or send e-mail is distracting and risky for motorists.
The 2013 study established a five-point scale for measuring driver distractions: 1 represents the mental workload of driving without distraction, while 5 represents severe distraction caused when drivers performed a complex math-and-memorisation test.
The new study rated distractions from eight different ways of interacting with a car by voice command.
The study found that using Apple's Siri (version iOS 7) to navigate, send and receiving texts, make Facebook and Twitter posts was most distracting to drivers.
Drivers who used an error-prone voice-based menu system to navigate to destinations were also more distracted.
Asking a computerised voice or a natural, recorded voice to play and compose emails and texts also proved to be distracting.
Using an error-free, voice menu system to navigate to destinations and issuing simple voice commands, like turn on heat or tune the radio were the least distracting.
"Some of the most advanced technology, such as Siri, can lead to high levels of distraction when you're trying to drive," Strayer said.
"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," he said.
