The interaction notion is a central concept which is studied by the I2C research group along several scientific research directions. The originality of the I2C research group is to combine these complementary and multi-disciplinary perspectives. The common roots of all the teams are the relations between individuals (physical or digital) and their environments (physical or computer). On the one hand, the MINT (methods and tools for gestural interactions), MJOLNIR (computing tools to empower users) and BCI (direct neural interfaces) teams are mainly concerned with local interactions between human users and computing systems through different kinds of interfaces. On the other hand, the SMAC team (multi-agent systems and collective behaviors) and NOCE (new tools for collaboration and education) teams focus on the links between local and global perceptions of interactions. We expect a form of collective intelligence to emerge from the study of these different interactions : a finer understanding and a better collaboration between individuals and their environments.