The first study involved 29 drivers who used a 2017 Volvo S90 equipped with Pilot Assist over a three-year period. Throughout the study, the system received several updates. The first group of drivers used the basic version of Pilot Assist, which required them to keep their hands on the steering wheel. The second group had access to an upgraded version with a lane-centering feature, while the third group used a version that included driver attention reminders. The study focused on highway driving, where Driver Assistance Systems are expected to be most effective.
The results showed that with Pilot Assist active, drivers from all three groups became more distracted by activities like eating, grooming, and using electronics. These distractions occurred most frequently when Pilot Assist was engaged, though they were still present when it was not. Even those who used the system infrequently displayed similar patterns of distraction. The study found that drivers became more complacent as they used the system longer, with distractions increasing over time. The report noted that drivers were distracted over 30 percent of the time when Pilot Assist was in use. Despite system updates, the overall conclusion was that Driver Assistance Systems contributed to increased driver distraction across all groups.
A second study, conducted by a separate team of researchers, focused on 14 drivers who had no prior experience with Driver Assistance Systems like Tesla’s Autopilot or Volvo’s Pilot Assist. Participants were given a 2020 Tesla Model 3 to see how often the vehicle’s attention reminders and warnings were triggered by driver behavior. Over the course of 12,000 miles, the system issued 3,858 attention-related warnings. About half of these warnings were issued when drivers had at least one hand on the steering wheel. Most of the warnings were initial reminders, to which drivers responded appropriately. However, there were 72 instances of escalation, with 16 leading to a full driver lockout, where the system prevented further use. Twelve of these lockouts came from a single driver.
In this second study, the rate of attention reminders per 1,000 miles increased by 26 percent from the first to the fourth week, while escalations decreased by 64 percent. As drivers became more familiar with the system, they spent less time responding to alerts, but the concerning finding was that they were more likely to take their hands off the wheel once the alerts stopped. According to the IIHS report, drivers seemed to anticipate the system’s sensors and worked around them, taking their hands off the wheel sooner each time.
Alexandra Mueller, the study’s lead author and IIHS Senior Research Scientist, pointed out that escalating attention reminders were effective in encouraging drivers to modify their behavior. However, the report emphasized the need for better safeguards to ensure these changes result in more attentive driving.
