Effects of an Unexpected and Expected Event on Older Adults' Autonomic Arousal and Eye Fixations During Autonomous Driving

Alice C Stephenson; Iveta Eimontaite; Praminda Caleb-Solly; Phillip L Morgan; Tabasum Khatun; Joseph Davis; Chris Alford

doi:10.3389/fpsyg.2020.571961

Effects of an Unexpected and Expected Event on Older Adults' Autonomic Arousal and Eye Fixations During Autonomous Driving

Front Psychol. 2020 Sep 18:11:571961. doi: 10.3389/fpsyg.2020.571961. eCollection 2020.

Authors

Alice C Stephenson¹, Iveta Eimontaite¹, Praminda Caleb-Solly², Phillip L Morgan³, Tabasum Khatun¹, Joseph Davis¹, Chris Alford¹

Affiliations

¹ Health and Applied Sciences, University of the West of England, Bristol, United Kingdom.
² Bristol Robotics Laboratory, University of the West of England, Bristol, United Kingdom.
³ Human Factors Excellence (HuFEx) Research Group, and Centre for Artificial Intelligence, Robotics and Human-Machine Systems (IROHMS), School of Psychology, Cardiff University, Cardiff, United Kingdom.

Abstract

Driving cessation for some older adults can exacerbate physical, cognitive, and mental health challenges due to loss of independence and social isolation. Fully autonomous vehicles may offer an alternative transport solution, increasing social contact and encouraging independence. However, there are gaps in understanding the impact of older adults' passive role on safe human-vehicle interaction, and on their well-being. 37 older adults (mean age ± SD = 68.35 ± 8.49 years) participated in an experiment where they experienced fully autonomous journeys consisting of a distinct stop (an unexpected event versus an expected event). The autonomous behavior of the vehicle was achieved using the Wizard of Oz approach. Subjective ratings of trust and reliability, and driver state monitoring including visual attention strategies (fixation duration and count) and physiological arousal (skin conductance and heart rate), were captured during the journeys. Results revealed that subjective trust and reliability ratings were high after journeys for both types of events. During an unexpected stop, overt visual attention was allocated toward the event, whereas during an expected stop, visual attention was directed toward the human-machine interface (HMI) and distributed across the central and peripheral driving environment. Elevated skin conductance level reflecting increased arousal persisted only after the unexpected event. These results suggest that safety-critical events occurring during passive fully automated driving may narrow visual attention and elevate arousal mechanisms. To improve in-vehicle user experience for older adults, a driver state monitoring system could examine such psychophysiological indices to evaluate functional state and well-being. This information could then be used to make informed decisions on vehicle behavior and offer reassurance during elevated arousal during unexpected events.

Keywords: autonomous vehicle; eye tracking; heart rate; human–machine interaction; human–machine interface; older adults; skin conductance level; trust.