ABSTRACT
The theater of human activity is an environment which may be considered to have three parts: a content, a geometry, and a dynamics. The content consists of both the actors and the objects with which they interact. The geometry is a description of the properties of the stage of action. The dynamics describes the rules of interaction between the actors arid the objects. The following discussion develops an analysis of these parts which is then applied to a concrete example of the unusual environment experienced by astronaut Dr. Joseph Allen while manually flying a Manned Maneuvering Unit in orbit. His experiences provide a reference point for considering the scientific bases of the interaction of human users with the artificial environments presented by computers.
