ABSTRACT
ACT-R is a production system theory that models the steps of cognition by a sequence of production rules that fire to coordinate retrieval of information from the environment and from memory. It is a cognitive architecture that can be used to model a wide range of human cognition. It has been used to model tasks from memory retrieval (Anderson, Bothell, Lebiere, & Matessa, 1998) to visual search (Anderson, Matessa, & Lebiere, 1997). The range of models developed-from those purely concerned with internal cognition to those focused on perception and action-makes ACT-R a plausible candidate to model a task like the air traffic control (ATC) simulation in this project because the task includes all of these various components. In all domains, ACT-R is distinguished by the detail and fidelity with which it models human cognition. It makes claims about what happens cognitively every few hundred milliseconds in the performance of a task. ACT-R is situated at a level of aggregation considerably above basic brain processes, but considerably below significant tasks like ATC. The new version of the theory has been designed to be more relevant to tasks that require deploying significant bodies of knowledge under conditions of time pressure and high information-processing demand. This is because of the increased con-
Christian Lebiere Carnegie Mellon University
cern with the temporal structure of cognition and the coordination of perception, cognition, and action.
