Practically all current multimedia applications are point-and-click applications where the visual display is static and nothing happens until the user clicks on the ``right spot''. The user may be involved either in an exploration or in a role-playing type of game but the objects that appear in the display can only be turned on and off---according to the user's interests. We call this type of display static because the objects it contains---text, graphic, photographs or video clips---always appear in the same position on the screen and their appearance is always triggered by the same type of action. The main drawback of static point-and-click displays is that the behavior of the user is reduced to clicking on all the the possible active spots and as a consequence the user may lose interest in the game or application after the space has been explored completely.
Figure: Movie clip in an Escher-esqe environment.
Dynamic displays offer instead a more compelling organization of the visual material layout. Each object has a notion of where to go, stay, its size, and movement according to the context in which it appears (background). Moreover the motor behavior of the objects is a function of their ``personality'' i.e. content and goals. The background is a dynamic object itself as it can attract or push away selectively certain objects in specific regions of the space and transform itself according the type and content of the visual material it holds (see fig. 2). Objects relate to themselves as a community of agents where hierarchy is built locally in space and time when two or more objects inhabit the same space and it is weighted by the user's past interactions with the display. As a result of the interaction of its objects amongst themselves and with the user, the display becomes a dynamic environment where the visual material re-arranges itself over time in a meaningful manner and is animated by its own internal dynamic and not uniquely by the intervention of the user. The display is responsible for where objects appear over time and how. When the objects are to appear is the result of the user's input together with the intern dynamic of the display and what visual material is shown depends on the orchestrator of the environment (the storyteller) that takes into consideration all of the above elements.
Blumberg's behavior based autonomous agents' model [Blumberg1994b] offers an ideal framework to develop dynamic displays. It provides tools to build animated characters for interactive virtual environments that are not only capable of autonomous action but respond also to the user's input.
Dynamic displays may also offer one possible answer to the aesthetic question raised by [Youngblood1989]:
How has the corpus of aesthetic strategies inherited in a medium like photography or film transferred over to electronic media and especially to the code?They allow: image transformation (``if mechanical cinema is the art of transition, electronic cinema is the art of transformation''), parallel event streams (``past, present and future can be spoken in the same frame at once''), temporal perspective, and the image as object (``with code it becomes a trivial matter to remove the image from the frame and treat it as an object, an image plane...'').
They also satisfy some of the criteria for creating compelling interactive systems proposed by Brenda Laurel in A Taxonomy of Interactive Movies [Laurel1989]:
... you need to think about intelligent animation--- characters who know what they look like and how they move ... it means generating (or retrieving) and then manipulating backgrounds as the action is pieced together...