Physiological Effects of Adaptive Cruise Control Behaviour in Real Driving

We examined physiological responses to behavior of an Adaptive Cruise Control (ACC) system during real driving. ACC is an example of automating a task that used to be performed by the user. In order to preserve the link between the user and an automated system such that they work together optimally, physiological signals reflecting mental state may be useful. We asked 15 participants to use an ACC at designated times while driving a track. When the ACC was activated, the car decelerated either strongly or softly, which was either according to expectation or not. Heart rate, eye blinks, and brain signals (EEG) were recorded. Heart rate and blink duration were the same following the announcement of an upcoming expected or unexpected deceleration profile. Heart rate and blink duration increased when a strong compared to a soft deceleration profile was announced, consistent with a state of arousal or startle. This was only found for the first half of the trials, when the driver was expected to be more alert and engaged (as also evidenced by decreasing heart rate, and increasing EEG alpha and blink duration over the trials). We conclude that for ACC behavior that is relevant for the driver, heart rate and blink duration may be used as a source of information about mental state elicited by the ACC, which could be used to evaluate driving experience.