led to a reduced number of different interaction devices but requires the driver to search through a range of menus to find a desired function. The driver now has to divide his or her visual attention between the primary driving task and a central information display (CID), which requires a lot of visual attention and thus distracts from the primary driving task.

Of course, with the increasing number of new driver-assistance systems, such as lane-departure warning or pedestrian-detection systems, one could argue that today’s cars also have “eyes” on the road, removing some visual load from the driver. However, from a legal perspective, the driver is still responsible for any traffic accidents. The user interface in the car should therefore be designed in the best possible way to prevent driver distraction and thus potential accidents.

Haptic Feedback in Multifunctional Car Systems

Usually there are three ways to
interact with multifunctional sys-
tems in the car:
• Buttons and additional controls
are arranged around or near the CID.
Some of these buttons are context
dependent; their meaning is shown
on the display next to the button.

• A multifunctional controller is used to navigate hierarchical menu structures, which are shown on a high-resolution CID.

• Virtual buttons must be
“pressed” directly on a touch-
enabled version of the screen.

There are also combinations of these interaction concepts available on the market.

Which haptic feedback do these
interaction concepts provide? In
the first case, a kind of haptic feed-
back is given by the control itself:
Even if the driver has to look for the
meaning of a context-dependent
button mounted around the screen,
the button lets the driver feel if
it has been pushed and therefore
communicates if a function has
been selected. When the driver
knows the meaning of a context-
dependent button, he or she can
even select it without looking.