Acclimation to partial autonomy can be dangerous, study shows

Trust is generally a good thing. In the case of partially autonomous driving systems, however, trust may increase risk, rather than decrease it.

The Insurance Institute for Highway Safety and the Massachusetts Institute of Technology’s AgeLab recently conducted a month-long study with 20 Massachusetts-based volunteers. The researchers found that as drivers became comfortable to their vehicles’ various driver-assist features, they became increasingly sloppy—dropping their hands off the steering wheel or looking away from the road to the console or their cell phone.

Are the results apocalyptic? Not exactly; the researchers’ findings are mostly in line with common sense. The more the vehicle absorbs driving duties for you, the more likely you are to get bored and want to do something else … like check your phone. Want to stay safe? Pay attention to the actual duty of driving.

We’ll break down the details of the study.

Ten of the participants spent the month driving a Range Rover Evoque and the other a Volvo S90. Both vehicles feature adaptive cruise control (ACC), which controls speed and following distance, but the S90 possesses a wider range of driver-assist tech. Volvo’s Pilot Assist, when activated, controls speed, following distance, and lane position. Volvo’s system qualifies as Level 2 autonomy and fits into the same SAE category as Cadillac’s Super Cruise and Tesla’s Autopilot; adaptive cruise control is Level 1.

At first, the observers didn’t notice much. At the end of the month, though, that changed. The likelihood that drivers would take their eyes off the road or their hands off the wheel had increased dramatically as the participants acclimated to the driver-assist features.

The IIHS noted that the Level 2 system used in the Volvo (Pilot Assist) had a much greater impact on driver awareness. By instilling more confidence in the vehicle’s ability to drive itself—the system not only minds the edges of the lane, but centers the car within it—Pilot Assist had a “dramatic” effect on driver attention.

“Drivers were more than twice as likely to show signs of disengagement after a month of using Pilot Assist compared with the beginning of the study,” says Ian Reagan, IIHS senior research scientist and the lead author of the study. “Compared with driving manually, they were more than 12 times as likely to take both hands off the wheel after they’d gotten used to how the lane centering worked.”

The adaptive cruise control system seemed to keep drivers a bit more occupied with the actual duty of driving; in the Volvo, however, drivers developed a preference for the more robust Pilot Assist system. “Only four out of 10 drivers used ACC alone after gaining familiarity with the systems,” the study reveals.

Interestingly, although Evoque drivers who favored ACC did pick up their phones more often than Evoque drivers who went the “manual” route, they didn’t commit the cardinal sin of actually texting.

The IIHS uses this study to promote its recommendations for more robust alerts—think icons, sounds, seat vibrations, or even brake pulses—to accompany partially autonomous driving systems. We’d like to point out that the simplest solution to the problem of distracted driving sits between the ears of every driver. Even if you’re not caught up in a transcendent experience of driving bliss every time you make a grocery run, pay attention. Cars are instruments, not conductors—not matter how well-equipped.