No Difference in Arousal or Cognitive Demands Between Manual and Partially Automated Driving: A Multi-Method On-Road Study

IntroductionPartial driving automation is not always reliable and requires that drivers maintain readiness to take over control and manually operate the vehicle. Little is known about differences in drivers’ arousal and cognitive demands under partial automation and how it may make it difficult for drivers to transition from automated to manual modes. This research examined whether there are differences in drivers’ arousal and cognitive demands during manual versus partial automation driving.MethodWe compared arousal (using heart rate) and cognitive demands (using the root mean square of successive differences in normal heartbeats; RMSSD, and Detection Response Task; DRT) while 39 younger (M = 28.82 years) and 32 late-middle-aged (M = 52.72 years) participants drove four partially automated vehicles (Cadillac, Nissan Rogue, Tesla, and Volvo) on interstate highways. If compared to manual driving, drivers’ arousal and cognitive demands were different under partial automation, then corresponding differences in heart rate, RMSSD, and DRT would be expected. Alternatively, if drivers’ arousal and cognitive demands were similar in manual and partially automated driving, no difference in the two driving modes would be expected.ResultsResults suggest no significant differences in heart rate, RMSSD, or DRT reaction time performance between manual and partially automated modes of driving for either younger or late-middle-aged adults across the four test vehicles. A Bayes Factor analysis suggested that heart rate, RMSSD, and DRT data showed extreme evidence in favor of the null hypothesis.ConclusionThis novel study conducted on real roads with a representative sample provides important evidence of no difference in arousal and cognitive demands. Younger and late-middle-aged motorists who are new to partial automation are able to maintain arousal and cognitive demands comparable to manual driving while using the partially automated technology. Drivers who are more experienced with partially automated technology may respond differently than those with limited prior experience

Drivers’ interaction with, and perception toward semi-autonomous vehicles in naturalistic settings

Partially automated vehicles are in actual use, and vehicles with higher levels of automation are under development. Given that highly automated vehicles (AVs) still require drivers’ intervention in certain conditions, effective collaboration between the driver and vehicle seems essential for driving safety. Having a clear understanding about drivers’ interactions with the current technologies is key to enhance them. Additionally, comprehending drivers’ perceptions toward AVs investigated in naturalistic settings seems important. This study particularly focuses on usability, workload, and acceptance of AVs as they are key indicators of drivers’ perceptions. Eight drivers conducted manual and automated driving in urban and highway environments. Their interactions and verbal descriptions were recorded, and perceptions were measured after each drive. Instances that may have negatively affected the perceptions were identified. The results showed that workload was higher, usability and acceptance were lower in automated driving in general. Findings show what should be considered to improve driver-autonomous vehicle interaction, in turn to help reduce workload, enhance usability, and acceptance