TWO EXPERIMENTS WERE CONDUCTED TO ANALYZE THE SPECIFIC EXTERNAL FACTORS THAT CONTRIBUTE MOST SIGNIFICANTLY TO STUDENT LEARNING. THE THREE HYPOTHESES TESTED WERE--(1) LEARNING IS INCREASED WHEN AN EXPERIMENTER ACTIVELY AUGMENTS THE PROGRAM BY REPHRASING PROGRAM STATEMENTS AND BY BRANCHING THE STUDENT TO DIFFERENT PARTS OF THE PROGRAM WHEN THE STUDENT HAS DIFFICULTY WITH A PARTICULAR TOPIC, (2) LEARNING IS INCREASED WHEN THE EXPERIMENTER HAS ACCESS TO DETAILED DISPLAYS OF CURRENT POST STUDENT PERFORMANCE, DESIGNED TO ASSIST HIM IN DIAGNOSING STUDENT-LEARNING PROBLEMS, AND (3) LEARNING IS INCREASED BY ALLOWING THE STUDENT TO BRANCH VOLUNTARILY IN THE PROGRAM AT ANY TIME DURING THE INSTRUCTION. THE THREE NONPROGRAM VARIABLES USED WERE (1) EXPERIMENTER AUGMENTATION, (2) DIAGNOSTIC INFORMATION, AND (3) STUDENT CONTROL. TWO EXPERIMENTS WERE CARRIED OUT. IN THE FIRST EXPERIMENT, 53 RANDOMLY SELECTED STUDENTS RECEIVED 6 EXPERIMENTAL TREATMENTS. EACH SUBJECT WAS DIRECTED TO APPROPRIATE PAGES IN HIS PROGRAM BY A DIGITAL DISPLAY ON HIS RESPONSE DEVICE. HE RESPONDED TO MULTIPLE CHOICE ITEMS BY PRESSING A BUTTON. FEEDBACK WAS GIVEN BY A RED/GREEN LIGHT ARRANGEMENT. THE COMPUTER RETAINED INFORMATION ON THE SUBJECT'S PERFORMANCE. THE SECOND EXPERIMENT STUDIED THE NONPROGRAM VARIABLES WITH 104 SUBJECTS IN 4 HIGH SCHOOL CLASSROOMS, WITH 4 TEACHERS SERVING AS EXPERIMENTERS. SUBJECTS WITH A PASSIVE EXPERIMENTER AND ADDITIONAL MATERIALS WERE (1) TOLD TO USE THE MATERIALS AS THEY SAW FIT, AND (2) GIVEN THE PROGRAM BOOKLET. SUBJECTS WITH AN ACTIVE EXPERIMENTER WERE GIVEN ONLY THE PROGRAM BOOKLET FOR USE IN THE CLASSROOM. THE STUDY DID NOT FIND THAT PROGRAM EFFECTIVENESS WAS DETERMINED BY VARIABLES NOT DIRECTLY UNDER PROGRAM CONTROL AS SUGGESTED BY THE HYPOTHESES SUBJECTED TO TEST. (HB)