As new unanticipated items are added to a memory, it must be able to reorganize itself, integrating the new items into its structure. The reorganization process must maintain the memory's structure and also build up the knowledge retrieval strategies need to search that structure. This study will present an algorithm for knowledge‐based memory reorganization. Included in that algorithm are processes for directed generalization and generalization refinement. A fact retrieval system called CYRUS which uses the algorithm is also presented. Conclusions are (...) drawn about maintaining accessibility in a conceptual memory, organizing generalized knowledge with respect to specific knowledge, and expected retrieval failures due to change over time in the memory's organization. (shrink)

This study presents a process model of very long‐term episodic memory. The process presented is a reconstructive process. The process involves application of three kinds of reconstructive strategies—component‐to‐context instantiation strategies, component‐instantiation strategies, and context‐to‐context instantiation strategies. The first is used to direct search to appropriate conceptual categories in memory. The other two are used to direct search within the chosen conceptual category. A fourth type of strategy, called executive search strategies, guide search for concepts related to the one targeted for (...) retrieval.A conceptual memory organization implied by human reconstructive memory is presented along with examples which motivate it. A basic retrieval algorithm is presented for traversing that stucture. Retrieval strategies arise from failures in that algorithm. The memory organization and retrieval processes are implemented in a computer program called CYRUS which stores events in the lives of former Secretaries of State Cyrus Vance and Edmund Muskie and answers questions posed in English concerning that information. Examples which motivate the process model are drawn from protocols of human memory search. Examples of CYRUS's behavior demonstrate the implemented process model. Conclusions are drawn concerning retrieval failures and the relationship of episodic and semantic memory. (shrink)

Design experiences can provide valuable opportunities for learners to improve their understanding of both science content and scientific practices. However, the implementation of design-based science learning in classrooms presents a number of significant challenges. In this article we present two significant challenges, bridging the design-science gap and overcoming time and material constraints, and a strategy for addressing them through software design in which explanation-construction scaffolding integrates with modeling and simulation. We present two software systems developed based on our strategy and (...) guidelines for integrating them into DBSL practices. We present a pilot study, the findings of which support the potential of our technology for responding to the identified challenges. A follow up study is presented which shows the affordances of our technology for improving the quality of classroom discourse, suggesting the potential of our strategy to enhance collaborative understanding and social construction of knowledge in DBSL environments. (shrink)