Glossary » intrusiveness
the property of a perceptual signal that enables it to draw attention from other activities. Perceptually, a sound or a bright flash can draw attention from people even when they are attending to something else. This property is useful for such applications as emergency warnings or to attract people to events of high importance or short duration. For instance, a ringing phone draws someone’s attention so that they’ll pick up the line before the caller hangs up.
On the other hand, in many situations intrusive signals can interfere with a higher-priority primary task. In those situations, most people want to turn off intrusive signals that don’t indicate emergencies, for instance, by turning off their phone ringer.
Paying attention to which types of signals can be intrusive (audio, flickering media, speech, animations, large changes in the visual field, touching), we can help the user control when and how they wish to be interrupted and avoid distracting them with unnecessary signals.
In the non-perceptual domain, many interruptions of work, such as spam email, are viewed as intrusive, to the extent that people cannot avoid the way in which those activities interfere with their desired activities.