Humans are limited in what they can simultaneously perceive. This is particularly
noticeable when driving a car and trying to do something else at the same time, such
as talking and changing the radio channel. In-car navigation systems are now making
new demands on a driver’s attention [3]. Extensive research has been carried out to
investigate how this cognitive demand might be reduced through the provision of
various kinds of collision detection systems and on how best to warn the driver of
possible collision using different modalities and also representing information in
multiple modalities (see [13]). Our research focuses on a less safety-critical aspect of
driving, although one that is still affected by the multiple stresses on a driver's attention:
navigating when using an in-car navigation system.