The dynamic of the gesture isn't used a lot in the domain of human-computer interaction, while it can help to define some simple heuristics to analyse the intents of the users. Its first use is related to the transfer function of isotonic devices. Those functions establish a relationship between the gesture of the user, done in the motor space with the pointing device (i.e. a mouse), and the movement of the pointer in the visual space. The transfer functions used by the modern operating systems are still not well known, even if some studies has shown they have an impact on user's performances. To characterize those functions, we have developed an electronic device which simulates a real mouse, and that can obtain the transfer functions of any system. We have then accessed the functions of the Windows, Linux and Mac systems, and we observed some visible differences between those functions. We have then tried to optimize those functions by reducing their number of degrees of liberty. By varying those parameters in an exhaustive way, we have then observed some significant differences that show there is a family of functions for which performances are optimal. Finally, we were interested in the use of the dynamics of the gesture in another context : the creation of discrete events, useful when dealing with contact-less interfaces, like the Kinect. We have shown that it is possible to distinguish between picking and drag'n'drop in a 3D interaction task. The technique is then improved in the case of small sized targets, and its application in a 2D interaction context is evaluated.
