  The emergence of new communication media such as blogs, online newspapers and
social networks allow us to go further in the understanding of human behavior.
Indeed, these public exchange spaces are now firmly planted in our modern
society and appear to be powerful sensors of social behavior and opinion
movements. In this paper, we focus on information spreading and attempt to
understand what are the conditions in which a person decides to speak on a
subject. For this purpose, we propose a set of measures that aim to
characterize the diffusion behavior. Our measures have been used on messages
related to two events that took place in January 2015: presentation by
Microsoft of a new virtual reality headset and the election of a political
party of radical left in Greece.
