Abstract
The design of man-computer dialog requires the underlying theoretical framework of basic concepts present in other applied arts. Four basic aspects of man-computer interaction are predictability, implication (the extensive use made by humans of context), experimentation (the importance of trial and error procedures), and motivation (the part played by feelings such as trust, hostility, etc.). Nonverbal communication should also be exploited to widen the rather limited `bandwidth' of current computer terminals.