Drivers who love talking to Apple’s Siri or Microsoft’s Cortana in the car might want to reconsider the potentially fatal distraction these “helpers” could cause. New studies show that voice-command technologies can interfere with driver attention for almost half a minute after use.
Many modern cars come equipped with “infotainment” systems that enable drivers to dial their contacts and to select their favorite music—all in the name of convenience and avoiding taking their eyes off the road. Drivers may also indulge in the habit of relying on hands-free smartphone assistants such as Siri, Cortana and Google Now. But two studies, conducted by the University of Utah for the AAA Foundation for Traffic Safety, show that such “voice command” technologies distract drivers more than listening to the radio or even making normal handheld or handsfree cellphone calls do.
“Most people think, ‘I hang up and I'm good to go,’” said David Strayer, a psychology professor at the University of Utah and senior author of the paper reporting the results of the studies, in a press release. “But that's just not the case. We see it takes a surprisingly long time to come back to full attention.”
Drivers going just 40 kilometers per hour (25 mph) remained distracted for up to 27 seconds after they supposedly turned their attention from “highly distracting” smartphone assistants or car infotainment systems. Even “moderately distracting” voice command systems left drivers distracted for up to 15 seconds later. In the first case, with 27 seconds of inattention, a distracted driver’s car would travel a distance equivalent to three football fields.
“The voice-command technology isn't ready,” said Joel Cooper, a research assistant professor of psychology at the University of Utah, in a press release. “It's in the cars and is billed as a safe alternative to manual interactions with your car, but the voice systems simply don't work well enough.”
Past research by the University of Utah and the AAA Foundation has yielded a ranking of driver distractions on a scale of 1 (least distracting) to 5 (most distracting). One of the new studies compared Apple’s Siri, Microsoft’s Cortana and Google Now by assigning two scores, each related to a particular scenario. The first scenario tested voice commands for making calls or changing music. The second tested drivers’ abilities to dictate text messages by voice command.
Microsoft’s Cortana ranked most distracting with scores of 3.8 and 4.1, followed by Apple’s Siri at 3.4 and 3.7. Google Now fared somewhat better with distraction scores of 3.0 and 3.3.
For comparison, older studies found cellphone calls to be “moderately distracting” with scores of 2.5 for handheld calls and 2.3 for handsfree calls. Listening to books on tape or to the radio ranked as “mildly distracting” at 1.7 and 1.2, respectively.
In the second new study, focused on vehicle infotainment systems in 2015 model year cars, the Mazda 6’s Connect system rated the most distracting with a score of 4.6; a score of 5 corresponds to a scientific test designed to overload driver attention.
Other highly distracting systems included the Ford Taurus with Sync MyFord Touch (3.1), Chevy Malibu with MyLink (3.4), Volkswagen Passat with Car-Net (3.5), Nissan Altima with Nissan Connect (3.7), Chrysler 200C with Uconnect (3.8), and Hyundai Sonata with Blue Link (3.8).
Infotainment systems ranked “mildly distracting” included the Chevy Equinox with MyLink (2.4), Buick Lacrosse with IntelliLink (2.4) and Toyota 4Runner with Entune (2.9). Chevy’s MyLink system had different distraction scores in different car models, which researchers attributed to different levels of road noise and the different vehicle microphones.
To top it all off, researchers found that levels of driver distraction did not decrease even with practice using the voice command systems. They tested 257 drivers ages 21 to 70 in the study of 2015 model-year vehicles. Another 65 drivers, ages 21 to 68, participated in testing of the three smartphone assistants on the road.
Such research builds on a series of past studies by the University of Utah and the AAA Foundation showing how voice command systems and other technologies can dangerously divert drivers’ attention. Perhaps the growing deployment of some autonomous vehicle systems such as automatic emergency braking can help prevent some disasters down the road. But for now, you should probably limit your conversations with Siri when you’re behind the wheel.
Jeremy Hsu has been working as a science and technology journalist in New York City since 2008. He has written on subjects as diverse as supercomputing and wearable electronics for IEEE Spectrum. When he’s not trying to wrap his head around the latest quantum computing news for Spectrum, he also contributes to a variety of publications such as Scientific American, Discover, Popular Science, and others. He is a graduate of New York University’s Science, Health & Environmental Reporting Program.