CONCEPTUAL INDEXING AND ACTIVE RETRIEVAL OF VIDEO FOR INTERACTIVE LEARNING ENVIRONMENTS

Selecting an instructive story from a video case base is an informatio n retrieval problem, but standard indexing and retrieval techniques [1 ] were not developed with such applications in mind. The classical mod el assumes a passive retrieval system queried by interested and well-i nformed users, In educational situations, students cannot be expected to form appropriate queries or to identify their own ignorance. System s that teach must, therefore, be active retrievers that formulate thei r own retrieval cues and reason about the appropriateness of intervent ion. The Story Producer for InteractivE Learning (SPIEL) is an active retrieval system for recalling stories to tell to students who are lea rning social skills in a simulated environment [2,3]. SPIEL is a compo nent of the Guided Social Simulation (GuSS) architecture [4] used to b uild YELLO, a program that teaches account executives the fine points of selling Yellow Pages advertising. SPIEL uses structured, conceptual indices derived from research in case-based reasoning [5,6]. SPIEL's manually-created indices are detailed representations of what stories are about, and they are needed to make precise assessments of stories' relevance. SPIEL's opportunistic retrieval architecture operates in t wo phases. During the storage phase, the system uses its educational k nowledge encapsulated in a library of ''storytelling strategies'' to d etermine, for each story, what an opportunity to tell that story would look like. During the retrieval phase, the system tries to recognize those opportunities while the student interacts with the simulation. T his design is similar to ''opportunistic memory'' architectures propos ed for opportunistic planning [7,8]. (C) 1997 Elsevier Science B.V.