The Walrus has a story, Driven to Distraction by John Lornic (April 2007) about new research showing how always-on communications technology is distracting us. The article references a research site interruptions.net with links to papers on interruption, which seems to be emerging as a focus for cognitive studies and HCI. See, for example the reports by Daniel McFarlane who defines interruption thus,
Human interruption is the process of coordinating abrupt change in people’s activities. (Interruption of People in Human-Computer
Interaction: A General Unifying Definition
of Human Interruption and Taxonomy, PDF)
Interruptions are not necessarily bad, and there is evidence (the Zeigarnik Effect) that we are better at remembering incomplete or interrupted tasks better than finished one, but when interruptions become the normal state we lose the ability to finish anything and become addicted to perpetual interruption. Interruption is the fundamental possibility of interactivity, it is the cutting into the continuum that surprises us.