Conceptual indexing and active retrieval of video for interactive learning environments

摘要

Selecting an instructive story from a video case base is an information retrieval problem, but standard indexing and retrieval techniques [1]were not developed with such applications in mind. The classical model assumes a passive retrieval system queried by interested and well-informed users. In educational situations, students cannot be expected to form appropriate queries or to identify their own ignorance. Systems that teach must, therefore, be active retrievers that formulate their own retrieval cues and reason about the appropriateness of intervention.The Story Producer for InteractivE Learning (SPIEL) is an active retrieval system for recalling stories to tell to students who are learning social skills in a simulated environment 2, 3. SPIEL is a component of the Guided Social Simulation (GuSS) architecture [4]used to build 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 two phases. During the storage phase, the system uses its educational knowledge encapsulated in a library of “storytelling strategies” to determine, 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. This design is similar to “opportunistic memory” architectures proposed for opportunistic planning 7, 8.