Physiological reactions to demands of vehicle control in semi-autonomous driving contexts
In the realm of SAE Level 3 automated driving, a series of studies have highlighted the significant effects of various factors on drivers' psychophysiological responses. These responses, which include gaze behaviours, heart rate, galvanic skin response (GSR), and facial expressions, were analysed in a high-fidelity simulator equipped with advanced technology.
Non-driving-related tasks (NDRTs) have been found to increase cognitive distraction, often leading to degraded gaze behaviour patterns. Drivers engaged in more complex or demanding NDRTs show delayed and less focused gaze shifts towards the driving scene during takeover requests. This increased distraction raises psychophysiological stress markers such as elevated heart rate and galvanic skin responses, reflecting increased arousal and workload.
Traffic density also plays a crucial role in takeover difficulty. Higher traffic density creates a more complex and demanding environment, leading to increased driver stress and workload during takeovers. This is evidenced by more erratic gaze patterns (shorter fixation durations, more saccades), elevated heart rate, and stronger GSR responses, indicating heightened vigilance and stress.
The takeover lead time, or the amount of time allowed for the driver to resume control, significantly influences driver state and takeover quality. Longer lead times allow drivers to better prepare and anticipate the takeover, thus exhibiting more stable gaze behaviour, lower heart rate, and reduced galvanic skin response signals. Conversely, shorter lead times produce more hurried and stress-related psychophysiological responses, such as increased heart rate and skin conductance, and facial expressions signaling stress or surprise.
The combination of these variables modulates drivers' situational awareness and emotional state during takeovers, impacting safety and takeover effectiveness. The use of a Smart Eye eye-tracking system enables detailed analysis of gaze patterns to assess attention and readiness, while the Shimmer3 GSR+ unit captures electrodermal activity related to arousal, and the Logitech webcam facilitates facial expression coding for emotions such as stress, confusion, or frustration.
During the study, each driver experienced 8 takeover events in a high-fidelity simulator. A total of 102 drivers participated, and their gaze behaviours, heart rate activities, galvanic skin responses, and facial expressions were recorded. The psychophysiological data was synchronized and visualized in real time using the study's platform software.
The findings suggest potential applications in driver monitoring systems and adaptive alert systems. They provide additional support for the value of using psychophysiological measures in automated driving, contributing to a safer and more efficient driving experience.
[1] Unspecified research studies on SAE Level 3 takeover transitions [2] The landscape of SAE Level 3 takeover transitions research in 2025 [3] Smart Eye, Sweden - Manufacturer of the Smart Eye eye-tracking system used in the study.
- In the context of SAE Level 3 automated driving, the combination of unspecified research studies and advanced technology has been instrumental in understanding the impact of factors like traffic density, takeover lead time, and non-driving-related tasks on drivers' psychophysiological responses.
- By 2025, technological advancements in science and technology may significantly revolutionize the landscape of SAE Level 3 takeover transitions research, leading to more efficient driver monitoring systems and adaptive alert systems that promote a safer driving experience.
