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A study was designed to investigate forms of human internal knowledge organization that facilitate the recall of information or its use for complex problem solving tasks. Three experiments, using college and high school physics students, were performed. The effects were studied by: (1) formulating explicit models of organization; (2) using extensive treatments to induce subjects to acquire specified organization; and (3) testing subjects' subsequent performance on recall and problem-solving tasks. A prescriptive model of hierarchical organization, was specified, designed to facilitate selective information retrieval, constructed by successive elaborations of a few top-level ideas most important for a specified task domain. Subjects with such a hierarchical organization performed appreciably better compared to subjects with a single-level organization of the same knowledge. Subjects also performed better on those tasks involving information included at higher levels of the subjects' internal hierarchical organization. In general, subjects of higher ability seemed better able to assimilate and exploit hierarchical organization. Various observations indicated that training methods used were quite effective in inducing a specified internal knowledge organization. (Author/MH)

A prescriptive model of problem-solving performance is described. The aim of the model is to specify explicitly how problems should be described initially in such a form as to facilitate their subsequent solution. According to the model, the process of initial problem description can be decomposed into two successive stages. The first uses general domain-independent knowledge to generate a "basic description" of a problem, the purpose of which is to identify explicitly the information specified and wanted in the problem, to introduce useful symbols, and to express the relevant information in various convenient symbolic representations. This basic description is then used to generate a "theoretical description" of the problem, that is, a deliberate redescription of the problem in terms of special concepts provided by the domain-specific knowledge base, involving the particular entities of interest in the problem, describing these entities in terms of concepts specifically provided by the knowledge base, and exploiting the known properties of these descriptive concepts. Focusing on mechanics (physics), the knowledge needed to generate theoretical problem descriptions is discussed, followed by experimental methods for testing the prescriptive model and selected results obtained from such experiments. (Author/JN)

This study examined a proposed procedure for constructing theoretical descriptions of mechanics problems, in particular, to determine if the procedure led to explicit and correct descriptions of the motion and interaction of systems and if the resulting theoretical descriptions facilitated generation of correct constraint equations and, hence, correct solutions to the problems. Twenty-four paid volunteers (undergraduate physics students) were randomly assigned to one of three groups: (1) model group, induced to solve problems in accordance with the full version of the proposed procedure; (2) modified-model group, induced to work with a less complicated version; and (3) a comparison group which solved problems without any external guidance. Criteria used as measures of good problem-solving performance and major classes of errors were established and adequacy of solution was assessed with respect to these performance measures. Very explicit rules for constructing initial problem descriptions were found to lead reliably to explicit and correct descriptions of motion and interaction. In addition, these descriptions were found to facilitate achievement of correct solutions. Specific examples of typical difficulties subjects encountered during problem-solving are also discussed. (Author/JN)