Behavior change associated with using partial automation among three samples of drivers during a 4-week field trial

Partial automation is still evolving. There is need to understand how behavior changes over time as drivers develop familiarity with the technology. In Reagan et al. (2021;Transportation Research Part F,82), volunteers driving a Volvo S90 with adaptive cruise control (ACC) and Pilot Assist, which couples ACC and continuous lane centering, hadhigher likelihood ofvisual-manual disengagement when using Pilot Assist in the second portion of a 4-week field trial compared with manual driving or when driving with Pilot Assist in the first portion.

We used the same analytical approach as Reagan et al. with three samples of drivers (n_A= 10,n_B= 10,n_C= 9). We estimated the odds of observing visual-manual distractions or both hands off the wheel across automation mode(manual [no automation], ACC, Pilot Assist) and study period(period 1, weeks 1 and 2; period 2, weeks 3 and 4).

Participants exhibited higher odds of distraction or driving hands-free in period 2 when using Pilot Assist relative to manual driving, but patterns differed across the groups. Pilot Assist use among groups A and B was associated with higher odds in period 2 relative to 1, whereas group C exhibited a high level of visual-manual distraction and hands-free driving with Pilot Assist throughout data collection.

Results suggest drivers show less attention to the road with the partial automation versions we tested compared with manual driving. Initial time using the technology appears to be associated with behavioral adaptation for many drivers new to the technology, but high exposure to the operational domain where the system performs well may supportthemore immediate increase in visual-manual distractionsevidenced among group C, which was unexpected based on prior work and makes an even stronger argumentfor driver-monitoring solutions that ensure adequate attention to the road.