Editor's note: An earlier version of this report incorrectly named the infotainment system used in the 2015 General Motors vehicles.
Car companies have turned to voice controls to cut down on distracted driving.
But systems such as Apple Inc.’s Siri electronic assistant, which automakers started installing in vehicles in 2013, may be as mentally taxing as the buttons and knobs they replace, research released today by the AAA Foundation for Traffic Safety suggests.
For the AAA-commissioned experiments, conducted by researchers at the University of Utah, test subjects in a driving simulator used Siri to send text messages, post updates on Facebook and modify their calendar appointments.
The test subjects averaged 4 points on a 5-point scale used to gauge mental strain while using Siri -- a heavier workload than experienced when talking on a handheld cell phone or changing the radio. Three virtual crashes took place in the driving simulator during the experiments. Two of them occurred while using Siri.
David Strayer, the University of Utah psychology professor who led the research, recalled watching footage of one of the crashes, in which the test subject rear-ended an abruptly stopping car. He described it as a textbook case of “inattentional blindness” -- the driver’s eyes “were looking out the windshield, her hands were on the steering wheel, but she was taken aback completely by that vehicle,” he said.
“The push to voice-based technology acknowledges that people need to keep their eyes on the road,” Strayer said in an interview. “Our research suggests that’s not enough. You need to be paying attention to what you’re looking at.”
Strayer noted that his research did not directly compare the overall risk associated with voice controls against the risk associated with other control systems. Mental workload is just one factor in distraction. Research by the National Highway Traffic Safety Administration has shown that the risk of getting into a crash rises threefold when a driver takes their hands off the steering wheel and eyes off the road.
Still, the findings could be unsettling for the auto industry, which has embraced voice controls over the past decade as anxiety has mounted about distracted driving. In many late-model cars, drivers can push a button on the steering wheel and speak a few words, prompting the car to program a new destination into its navigation system, change the radio station or place a phone call.
The findings could also catch the attention of U.S. auto-safety regulators, who have embraced voice controls to make roads safer. NHTSA put out guidelines in April 2013 to minimize distractions from in-car control systems that use buttons, knobs and touchscreens -- but refrained for the time being to recommend limits on voice controls.
In addition to Siri, Strayer’s research team tested the voice control systems that automakers offer in systems such as Toyota Entune, Ford Sync and Chevrolet MyLink.
Cognitive load varied widely from brand to brand. The best performer, Toyota’s Entune, scored a 1.7 on the 5-point cognitive workload scale, roughly equivalent to listening to an audio book. The worst, Chevrolet MyLink, scored a 3.7 out of 5.
“We believe that this high level of workload was elicited by system errors and the prolonged duration of the task,” the researchers wrote in their research paper, referring to the MyLink system.
Michael Green, a spokesman for the AAA Foundation, said the group wants voice controls to be as safe as listening to the radio. He praised the EnTune system in particular, urging other automakers to follow Toyota’s lead.
The Alliance of Automobile Manufacturers, a Washington, D.C. lobbying group that counts both General Motors and Toyota among its members, said it needed more time to review the research. A spokesman said the group continues to believe that driving is safest when the driver keeps their hands on the wheel and eyes on the road.
“This study focused on a very narrow aspect of distraction: cognitive load,” Wade Newton, the spokesman, wrote in an e-mail. “Because the study did not address either visual or manual distractions, the results tell us very little about the relative benefits of in-vehicle versus handheld systems or about the relationship between cognitive load and crash risks in the real world.”
Annalisa Bluhm, a Chevrolet spokeswoman, said that the University of Utah research used Cruze and Impala sedans from model year 2013 that were equipped with older, less sophisticated voice recognition systems.
She said GM still believes hands-free controls are safer than using a cellphone behind the wheel, and that it is working hard to improve those systems.
GM was an early adopter of Siri, offering it into the Chevrolet Spark and Sonic starting in February 2013, and updated its MyLink system for 2015. (Strayer said that the University of Utah team is re-doing its testing with 2015 models, and intends to release its findings in the first quarter of 2015.)
“The fewer steps to get what you want, the more it helps,” Bluhm said in an interview. “It takes less cognitive horsepower if you’re just saying ‘play The Beatles,’ instead of saying to play a certain album and play a certain song. … We’re committed to improving that experience. We know it’s important. And this is an area where six months can make a huge difference.”
Which system is better?
NHTSA is working on guidelines for voice controls as a third phase of its distraction guidelines. A second phase will cover cell phones and other portable devices. The big question is which control system -- whether a touchscreen, buttons, voice controls, or a cell phone -- is safe for which functions behind the wheel.
Russ Rader, a spokesman for the Insurance Institute for Highway Safety, said the group is doing its own study with Massachusetts Institute of Technology researchers to explore whether hands-free systems are truly less distracting than handheld systems.
Despite their potential, they can backfire, he said.
“If the voice recognition system is not reliable or the commands you have to use get too complicated, that can take your eyes off the road, too,” Rader said in an interview. If the system doesn’t work as expected, he added, “that’s going to tempt you to look at the screen to figure out what’s wrong.”