The Information Dynamics Laboratory at HP Labs has produced another interesting quantitative study (PDF), using Digg.com as a living laboratory to study the way attention to new items propagates and decays online:

The stretched exponential relaxation often occurs as the result of multiple characteristic relaxation time scales. This is consistent with the fact that the decay rate of a story on digg.com depends on many factors, such as the story’s topic category and the time of day when it appears on the front page. The measured decay factor rt is thus an average of these various rates and describes the collective decay of attention.

These measurements, comprising the dynamics of one million users attending to thousands of novel stories, allowed us to determine the effect of novelty on the collective attention of very large groups of individuals, while nicely isolating both the speed of propagation of new stories and their decay. We also showed that the growth and decay of collective attention can be described by a dynamical model characterized by a single novelty factor which determines the natural time scale over which attention fades. The exact value of the decay constant depends on the nature of the medium but its functional form is universal. These experiments, which complement large social network studies of viral marketing are facilitated by the availability of websites that attract millions of users, a fact that turns the internet into an interesting natural laboratory for testing and discovering the behavioral patterns of large populations on a very large scale.

The Information Dynamics Laboratory at HP Labs has produced another interesting quantitative study (PDF), using Digg.com as a living laboratory to study the way attention to new items propagates and decays online:
The stretched exponential relaxation often occurs as the result of multiple characteristic relaxation time scales. This is consistent with the fact that the decay [...]