THE ROLE OF COGNITIVE ARCHITECTURE IN MODELING THE USER - SOARS LEARNING MECHANISM

What is the role of a cognitive architecture in shaping a model built within it? Compared with a model written in a programming language, th e cognitive architecture offers theoretical constraints. These constra ints can be ''soft,'' in that some ways of constructing a model are fa cilitated and others :made more difficult, or they can be ''hard,'' in that certain aspects of a model are enforced and others ruled out. We illustrate a variety of these possibilities. In the case of Soar, its learning mechanism is sufficiently constraining that it imposes hard constraints on models constructed within it. We describe how one of th ese hard constraints deriving from Soar's learning mechanism ensures t hat models constructed within Soar must learn a display-based skill an d, other things being equal, must find display-based devices easier to learn than keyboard-based devices. We discuss the relation between ar chitecture and model in terms of the degree to which a model is ''comp liant'' with the constraints set by the architecture. Although doubts are sometimes expressed as to whether cognitive architectures have any empirical consequences for user modeling, our analysis shows that the y do. Architectures play their part by imposing theoretical constraint s on the models constructed within them, and the extent to which the i nfluence of the architecture shows through in the model's behavior dep ends on the compliancy of the model.