Driver arousal and workload under partial vehicle automation: A pilot study
archive: archived pipeline: cataloged verified
Abstract
Semi-automated vehicles (Level-2) provide driving assistance, but they still require driver supervision to maintain safe driving. However, little is known about potential differences in drivers' cognitive states during manual vs. Level-2 automated driving. The current study systematically examined the effects of manual and Level-2 driving on drivers' arousal and workload during on-road driving. No differences between the two driving modes were found for the five outcomes that assessed cognitive arousal and workload (i.e., heart rate, root mean square of successive heart period differences, EEG alpha power, and hit rate and reaction time on a secondary task). A Bayes Factor analysis suggested that there is strong evidence that cognitive arousal and workload during Level-2 driving did not differ from manual driving. These novel and theoretically meaningful findings provide strong evidence of similar cognitive arousal and workload states in Level-2 automation and manual driving.
Summary
On-road pilot study (HFES Annual Meeting Proceedings, 2020) comparing driver cognitive arousal and workload between manual (Level-0) and partial automation (Level-2) driving in three production vehicles (Cadillac CT6, Tesla Model S, Volvo XC90). Twenty-eight participants drove a 44-mile section of I-80 in Utah at 75 mph in counterbalanced Level-0 and Level-2 conditions. Five outcome measures captured arousal and workload: heart rate (BPM), RMSSD heart-rate variability, parietal EEG alpha power, and DRT hit rate and reaction time. A linear mixed-effects model showed no significant effect of automation on any of the five measures. Bayes Factor analyses (BF range .030-.059) provided strong evidence in favor of the null hypothesis, indicating equivalent arousal and workload across Level-0 and Level-2 driving. Authors note participants were new to Level-2 automation; experienced users may differ.
Key finding
In drivers new to Level-2 automation, cognitive arousal and workload during partial automation are equivalent to manual driving. Bayes Factors of .030-.059 across heart rate, RMSSD, EEG alpha, DRT hit rate, and DRT reaction time provide strong evidence for the null, suggesting these drivers remained engaged with the driving task rather than becoming disengaged or overloaded.
Methodology
on_road
Sample size: N=28 (24% female; M_age=29.29, SD=4.27). Inclusion criteria: valid license, no at-fault crashes in past 2 years, >=10 hours/month driving, no neurological or heart conditions, no prior Level-2 experience.
Quality score: 5 / 5