Proceedings of the Annual Meeting of the Cognitive Science Society

NTD-Soar is a model of the perceptual, cognitive, and motor actions performed by the NASA Test Director as he utilizes the materials in his surroundings and communicates with others to prepare for a Space Shuttle Launch. The model, built within the framework of a serial symbolic architecture, is based on a number of independently designed general cognitive capabilities as well as a cognitive analysis of a particular task. This paper presents a detailed description of the model and an assessment of its performance when compared to human data. NTD-Soar's ability to display human-like real-time performance demonstrates that symbolic models with a serial bottleneck can account for complex behaviors which appear to happen in parallel, simply by opportunistically interleaving small elements of the different subtasks.