Representing cognitive activity in complex tasks

Although cognitive theory has been recognized as essential for the analysis of human-computer interaction (HCI), the representations that have been de veloped have been directed more toward theoretical purposes than practical application. To bridge the gap between theory and application, representati ons need to satisfy requirements for broad scope, a unified theoretical bas is, and abstraction. Interacting cognitive subsystems (ICS) is proposed as a unified cognitive theory that can be used as the basis for such represent ations, and two approaches based on the theory are described. One entails t he description of cognitive task models, which are a relatively complete re presentation of the cognitive activity required of a user in the course of an interaction. The other entails the production of less complete diagramma tic notations, which are intended to provide support in small-scale problem identification and resolution and which can be applied across tasks, visua l interface, and sound interface issues and can handle static and dynamic s ituations. Although the former can be implemented in a production-rule expe rt system (ICSpert) and, therefore, does not require detailed modeling know ledge on the part of the analyst, the latter is a pencil-and-paper techniqu e that does require theoretical knowledge but is intended to facilitate the acquisition of such knowledge in the interest of educating its users about the human aspects of HCI. The representations differ in the knowledge requ ired for their use, in the support that they offer, and in the situations f or which they are appropriate. They have been used to represent problems fr om experimental situations, core HCI scenarios, and real-world design proje cts. They share breadth of scope and abstraction, and their parent theory s upports transfer of knowledge across domains of application and from older to newer technologies and feedback between the domain of application and th e domain of theory.