This research area aims to define, implement and validate innovative interaction techniques between man and machine. Techniques to facilitate computer-user communication in which two-dimensional and three-dimensional environments are researched. In this area some of the studies are: the definition of natural interfaces (using the human body to interact), the use of different devices that provide sensations as stereoscopy and force feedback, evaluation of adequacy of graphical interfaces in information systems and the use of software testing techniques to evaluate programs with graphical output.