Date of Award

Fall 12-2022

Document Type


Degree Name

Master of Science (MS)



Committee Director

Jing Chen

Committee Member

Yusuke Yamani

Committee Member

Catherine Glenn


Drivers of vehicles that use a driving automation system were tasked with supervising the vehicle to ensure it was functioning properly. This task required drivers to stay vigilant of the roadway while being ready to intervene in the case of an unexpected hazard that the driving automation system may not have detected. This study investigated whether reclining a drivers’ seatback to more comfortable postures would affect their vigilance performance over time. Vigilance performance was measured by correct detections, false alarms, response sensitivity, response bias, and response time to hazardous events. Forty-five participants were recruited and randomly assigned to a postural condition with a seatback that was upright, slightly reclined, or very reclined. Their performance and comfort were measured over the course of a 40-minute driving task that used SAE Level-2 automation. Participants were tasked with classifying whether the neighboring vehicles were hazardous or safe. Based on our performance measures, we found a vigilance decrement that was potentially caused by cognitive underload stemming from the low task demand. We also found that posture did not affect any of the performance measures and that comfort ratings were similar despite the postural manipulation. This result indicates that drivers of vehicles with a driving automation system are free to adjust their seatback from an upright to very reclined posture without concern for their vigilance performance.


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Copyright, 2022, by Jeremiah Gabriel Ammons, All Rights Reserved.





Included in

Psychology Commons