STUDY OF CHARACTERISTICS CONTRIBUTING TO THE EFFECTIVENESS OF VISUAL DEMONSTRATIONS.

SLIDES OF SELECTED TEXTBOOK ILLUSTRATIONS, DRAWN TO HIGHLIGHT THE PERTINENT AREAS OF THE ILLUSTRATION BY MEANS OF SHADING AND ILLUMINATION, WERE USED TO EVALUATE THEIR EFFECTIVENESS OVER SELECTED SLIDES OF CONVENTIONAL ILLUSTRATIONS AND DIAGRAMS IN WHICH ALL DETAILS WERE PROMINENTLY DISPLAYED. WHEN THE CONTROL SLIDES WERE PRESENTED, A TEACHER USED A POINTER TO INDICATE THE PERTINENT DETAIL IN COORDINATION WITH THE DIALOG. THE PROJECTED SLIDES WERE ACCOMPANIED BY A TAPED DIALOG. JUNIOR HIGH SCHOOL, HIGH SCHOOL, AND COLLEGE STUDENTS IN SCIENCE COURSES COMPRISED THE STUDY POPULATION AND WERE DIVIDED INTO EXPERIMENTAL AND CONTROL GROUPS. BOTH GROUPS RECEIVED THE SAME DIALOG, ONLY THE SLIDES DIFFERED. THE SLIDES AND ACCOMPANYING DIALOG WERE MADE FOR THE FIELDS OF BIOLOGY, CHEMISTRY, PHYSICS, GEOMETRY, STATISTICS, AND MECHANICS AND WERE PRESENTED IN ONE OR TWO LECTURES OF ABOUT 40 MINUTES DURATION. RESULTS OF TESTS INDICATED THAT THE EXPERIMENTAL SLIDES TENDED TO BE SOMEWHAT SUPERIOR TO CONVENTIONAL SLIDES IN LECTURES ON BIOLOGY AND MECHANICS, REQUIRING ILLUSTRATION OF CONCRETE OBJECTS. IN SUCH COURSES AS CHEMISTRY AND PHYSICS, REQUIRING EXTENSIVE PROBLEM-SOLVING, THE SUPERIORITY OF THE CONVENTIONAL APPROACH WAS INDICATED. IN GEOMETRY AND STATISTICS, THE DIFFERENCES WERE NEGLIGIBLE. ANALYSIS OF EFFECTIVE EXPERIMENTAL SLIDES LED THE AUTHOR TO INFER THAT AN EFFECTIVE VISUAL DEMONSTRATION CONTAINS NO EXTRANEOUS DETAILS AND IS CAPABLE OF COMMANDING ATTENTION BY SELECTIVE SHIFTS IN FIGURE-GROUND CONTRAST. (PM)