Embodied models as simulated users: Introduction to this special issue on using cognitive models to improve interface design

Cognitive models provide a means for applying what is known from psychology to the design of interfaces, thereby improving their quality and usability. Existing uses of models include predicting time and errors for users to perform tasks, acting as embedded assistants to help users perform their tasks, and serving as surrogate users. Treating the design of human-computer interfaces as a form of engineering design requires the development and application of user models. A recent trend is for models to be built within the fixed framework of a cognitive architecture, which has been extended by the addition of simulated eyes and hands, enabling the construction of embodied models. Being embodied allows models to interact directly with interfaces. The resulting models can be used to evaluate the interfaces they use, and serve as explanations of users' behavior. The papers in this Special Issue point to a new route for the future, one in which models built within embodied cognitive architectures provide information for the design of better interfaces.