The past twenty years have witnessed a revolution in the use of computers in virtually every facet of society. While this revolution has been largely fueled by dramatic technological advances, the efficient application of this technology has been made possible through advances in the paradigms defining the way users interact with computers. Today's massive computational power would probably have limited sociological impact is users still communicated with computers via the binary machine language codes used in the 1950's. Instead, this primitive paradigm was replaced by keyboards and ASCII character displays in the 1970's, and the 'mouse' and multiple-window bit-mapped displays in the 1980's. As continuing technological advances make even larger computational power available in the future, advanced paradigms for man-machine interaction will be required to allow this power to be used efficiently in a wide range of applications. Looking ahead into the 21st century, we see paradigms supporting radically new ways of interacting with computers. Ideally, we would like these interactions to mimic the ways we interact with objects and people in the physical world, and, to achieve this goal, we believe that it is essential to consider the exchange of video data into and out of the computer. Paradigms based on visual interactions represent a radical departure from existing paradigms, because they allow the computer to actively seek out information from the user via dynamic scene analysis. For example, the computer might enlarge the display when it detects that the user if squinting, or it might reorient a three- dimensional object on the screen in response to detected hand motions. This contrasts with current paradigms in which the computer relies on passive switching devices (keyboard, mouse, buttons, etc.) to receive information. Feedback will be provided to the user via dynamic scene synthesis, employing stereoscopic three-dimensional display systems. To exploit the synergism between analysis and synthesis, we will need common data representation used by both. To illustrate, we give some typical scenarios which could be made possible by these new paradigms.