Perhaps the most basic principle is that the interface should be designed around the needs of the user rather than added on after a system has been completed, thus serving the constraints imposed by the system. Interface that accept voice and gesture concurrently will give richer control to users who must move about while controlling systems and make possible a variety of virtual reality applications. Likewise, video and sound output together provide a more powerful communication channel for information flow. In addition to advances in physical interface components, there is active research in conceptual components such as interaction styles. Direct manipulation interfaces will continue to emerge and more robust adaptive systems will be developed that change according to the type of task and user experience level.
Intelligent agents are also under development.
Agents can be assigned specific tasks by the user and then sent out to execute those tasks. The next metaphor of the computer world may be the theatre or command center, where directors assign roles to software agents and examine the results of their subsequent performances. Lessons from information retrieval studies. The Psychology of Human-Computer Interaction. Lawrence Erlbaum Assoc.