The Design of a Cooperative Respondent

In this paper we discuss a phenomenon we call integration discontinuity. Bringing together two components of a computer system seldom produces a seamless joint. Tacking on a "front end" to a finished application often produces poor user interfaces. Developing a functioning application from a finished user interface may compromise system design or imply functionality the system cannot supply. If a new modality is introduced into a developed user interface, the behavior it allows may overlap the existing behavior of the interface in unfavorable ways, and it may change the user's model of system behavior. We discuss integration discontinuity as it occurs between system components, interface modalities, and user's models a system before and after a new interface mechanism is introduced.