THE RELATIVE EFFECTIVENESS OF TWO TYPES OF VISUAL MEDIA FOR THE DEVELOPMENT OF A THREE-DIMENSIONAL CONCEPT OF A GIVEN ANATOMICAL REGION WAS INVESTIGATED. EXPERIMENTAL AND CONTROL GROUPS WERE RANDOMLY SELECTED FROM 119 FIRST-YEAR MEDICAL AND DENTAL STUDENTS IN AN HISTOLOGY CLASS. BOTH GROUPS ATTENDED THE SAME ONE-HOUR LECTURE. FOLLOWING THE LECTURE THE EXPERIMENTAL GROUP WAS TWICE SHOWN A FIVE-MINUTE ANIMATED SERIAL FILM THAT HAD BEEN CONSTRUCTED FROM APPROXIMATELY 400 SECTIONS OF HUMAN ORAL TISSUE. THE SECTIONS WERE TAKEN IN AN ORDERLY SEQUENCE FROM THE TISSUE, AND ALTHOUGH TWO-DIMENSIONAL, PRODUCED THE ILLUSION OF THREE-DIMENSIONALITY WHEN SHOWN AS A MOTION PICTURE FILM. THE CONTROL GROUP WAS TWICE SHOWN A SERIES OF FORTY 2 X 2 SLIDES THAT HAD BEEN DEVELOPED FROM KEY SECTIONS INCLUDED IN THE ORIGINAL 400. THE SAME NARRATION WAS USED FOR BOTH PRESENTATIONS. AFTER STUDENTS IN BOTH GROUPS HAD BEEN TESTED FOR ACHIEVEMENT, THEY WERE EXPOSED TO THE PRESENTATION THAT THEY HAD NOT PREVIOUSLY SEEN. FOLLOWING THIS VIEWING, STUDENT REACTIONS TO THE TWO APPROACHES WERE SURVEYED. WHEN ANALYSIS OF VARIANCE WAS APPLIED TO ACHIEVEMENT TEST SCORES, NO SIGNIFICANT DIFFERENCE IN ACHIEVEMENT WAS DETECTED BETWEEN GROUPS OR BETWEEN MEDICAL AND DENTAL STUDENTS. CHI-SQUARE ANALYSIS OF NON-COGNITIVE, ATTITUDINAL ITEMS REVEALED THAT BOTH THE MEDICAL AND DENTAL STUDENTS PREFERRED THE FILM TO SLIDES AS A MEANS FOR (1) STUDYING, AND (2) CONVEYING THREE-DIMENSIONAL CONCEPTS. THE SLIDE GROUP INDICATED THESE PREFERENCES MORE FREQUENTLY THAN DID THE FILM GROUP. (AG)