Situated Plan Attribution1

Plan recognition techniques frequently make rigid assumptions about the student's plans, and invest substantial effort to infer unobservable properties of the student. The pedagogical benefits of plan recognition analysis are not always obvious. We claim that these difficulties can be overcome if greater attention is paid to the situational context of the student's activity and the pedagogical tasks which plan recognition is intended to support. This paper describes an approach to plan recognition called situated plan attribution that takes these factors into account. It devotes varying amounts of effort to the interpretation process, focusing the greatest effort on interpreting impasse points, i.e., points where the student encounters some difficulty completing the task. This approach has been implemented and evaluated in the context of the REACT tutor, a trainer for operators of deep space communications stations.