Information retrieval systems that support searching of large textual databases are typically accessed by trained search intermediaries who provide assistance to end users in bridging the gap between the languages of authors and inquirers. We are building a thesaurus in the form of a large semantic network .to support interactive query expansion and search by end users. Our lexicon is being built by analyzing and merging data from several large English dictionaries; testing of its value for rea'ieval is with the SMART and CODER systems.

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This paper describes a preliminary study of the use ofanalogic reasoning in learning a new computer language. Subjects read text describing an invented LISP dialect. and then solved simple problems and described language constructs on the basis of the test. The experimental subjects all had programming experience in FORTRAN77 and Pascal, and were concurrently studying assembly language. Six factors indicating use ofanalogy with a familiar computer language were studied: correctness, occurrences of three-control constructs. FORTRAN style expression treatment, and FORTRAN/Pascal style argument handling. Of these factors, four showed statistically significant results. and one additional factor proved highly significant. Hence the results support the hypothesis that students use analogies in learning new languages. (Keywords: analogy, programming, teaching methods.) Reasoning by analogy is widely accepted as playing a role in learning behavior. However, direct evidence on how individuals apply analogies in specific learning situations remains scant. In particular, little to no attention has been paid to learning computer science related material. The study reported here investigates how students use analogy in extending their knowledge by examining how students who know at least one computer langauge learn an unfamiliar one.Analogic reasoning relies on detected similarities with a familiar domain to form a hypothesis or reach a conclusion about a given problem. When using analogies, people assume that if two things are alike in some respects, they are probably alike in others. That assumption is used to provide conjectures about a new domain on the basis of similarities with a familiar one. More complete accounts of what constitutes an analogy follow in the section on background.Like any form of reasoning on the basis of incomplete information, analogic reasoning presents some hazards. Using analogies to understand a new domain introduces preconceptions about the new material. In the case studied here, trying to learn a new computer language, relying on similarities to a previously learned language may cause students to overlook some features of the new langauge or even to redefine them to fit the familiar pattern. The resulting errors provide a "handle" on the use of analogy by revealing the presumed pattern. 254SUMMER 1985