Voice-recognition software that many automakers tout as a safer alternative to handheld devices can still divert drivers' attention, a new study published by AAA found.
The technology is alluring because it allows drivers to do things like change the radio station or compose a text message without removing their hands from the wheel or their gaze from the road. But many of those tasks increase a driver's cognitive workload. Depending on the situation, that can be dangerous.
Researchers noted that workload ratings were the highest on their scales when participants in the study used Siri.
"It's especially problematic, because you can be distracted and not know it," J. Peter Kissinger, president of the AAA Foundation for Traffic Safety, told Autoblog. "That's the nature of mental distraction. It's hard to appreciate. ... Often, you don't know you're distracted until it's too late."
There's significant variation in the results of the study. Simple, single-task car commands for operations like changing the radio station caused minimal increases in workload, about the same as listening to an audio book. Composing information using speech-to-text technology was more burdensome, and using menu-based functions caused a high level of cognitive workload.
Siri-based interactions posed the highest levels of distraction, according to AAA. Researchers noted that workload ratings were the highest on their scales when participants in the study used Siri, and two of the three simulator crashes they observed during the study of 36 participants came while the subjects were interacting with Siri. The subjects weren't looking at nor making contact with their iPhones during these interactions.
"Common issues involved inconsistencies in which Siri would produce different responses to seemingly identical commands," the researchers wrote. "In other circumstances, Siri required exact phrases to accomplish specific tasks and subtle deviations from that phrasing would result in a failure. ... Some participants also reported frustration with Siri's occasional sarcasm and wit."
It wasn't just the complexity of the task that caused variations in level of distraction – the variations could also be dependent on the particular make and model of the car being tested. In a companion study, AAA evaluated the cognitive distraction caused when using voice-recognition software in six of the most popular infotainment systems.
Perhaps not surprisingly, users performed the best on the systems on which it took the shortest amount of time to complete a task.
The best of the bunch was Toyota's Entune, AAA found. Researchers say the voice-based interactions with Entune actually posed a lower workload on participants than listening to an audio book. The other five systems all caused increases in cognitive workload. AAA called the results for Toyota "a best-case scenario."
"We survey motorists and two out of three still believe that hands-free is safer than hand-held, and that's partly because that's what they keep hearing from the manufacturers."
– J. Peter Kissinger
Toyota studies cognitive distraction at its Collaborative Safety Research Center in Ann Arbor, MI, and has established partnerships with several universities to understand the links between cognitive demands on driving behavior. "We are pleased to see that Toyota's goal of simple design interfaces with low demands has scored well in this study," the company said in a written statement.
On the other end of the spectrum, AAA says the Chevrolet MyLink infotainment system's voice-recognition technology imposed significantly more mental burden on its users and its users performed the poorest.
"We believe that this high level of workload was elicited by system errors and prolonged duration of the task," researchers wrote. "In many circumstances, participants were unable to complete the music functions task at all during the drive. For many of the drivers, the first reaction was to simply give up trying."
"Given the circumstances, this is perhaps the safest decision. We feel that it is unrealistic to expect drivers to persist in failed attempts to use their voice to achieve a goal which can be accomplished manually by the flick of a switch and the press of a button."
A General Motors spokesperson did not return a request for comment on MyLink.
Overall, Kissinger says the studies join a growing body of research that suggests that, just because these tasks are hands-free, does not mean there are not heightened risks involved. He suggests manufacturers need to pay far more attention to hands-free distracted driving than they have in the past, and that motorists need to exercise caution in using any of these devices, hands-free or not.
"We survey motorists and two out of three still believe that hands-free is safer than hand-held, and that's partly because that's what they keep hearing from the manufacturers," he said. "Motorists need to know this remains a serious problem."