  Driver assistance systems are designed to increase comfort and safety by
automating parts of the driving task. At the same time, modern in-vehicle
information systems with large touchscreens provide the driver with numerous
options for entertainment, information, or communication, and are a potential
source of distraction. However, little is known about how driving automation
affects how drivers interact with the center stack touchscreen, i.e., how
drivers self-regulate their behavior in response to different levels of driving
automation. To investigate this, we apply multilevel models to a real-world
driving dataset consisting of 31,378 sequences. Our results show significant
differences in drivers' interaction and glance behavior in response to
different levels of driving automation, vehicle speed, and road curvature.
During automated driving, drivers perform more interactions per touchscreen
sequence and increase the time spent looking at the center stack touchscreen.
Specifically, at higher levels of driving automation (level 2), the mean glance
duration toward the center stack touchscreen increases by 36% and the mean
number of interactions per sequence increases by 17% compared to manual
driving. Furthermore, partially automated driving has a strong impact on the
use of more complex UI elements (e.g., maps) and touch gestures (e.g.,
multitouch). We also show that the effect of driving automation on drivers'
self-regulation is greater than that of vehicle speed and road curvature. The
derived knowledge can inform the design and evaluation of touch-based
infotainment systems and the development of context-aware driver monitoring
systems.
