IN TYPICAL MCLUHAN STYLE, THE AUTHOR OF THIS WORKING PAPER TRACES HISTORICAL-CULTURAL TRANSITIONS FROM PHONETIC ALPHABET TECHNOLOGY TO MEDIA OF THE NEW ELECTRONIC TECHNOLOGY. THESE MEDIA ARE VIEWED AS EXTENSIONS OF MAN'S SENSES, AND AS LANGUAGES THEMSELVES, WHOSE ONLY CONTENT ARE OTHER MEDIA. EACH MEDIUM (E.G. SPEECH, WRITING, PRINT, PHOTOGRAPHY, THE PRESS, RADIO, TELEVISION, FILM, PHONOGRAPH) IS DISCUSSED IN TEXT, AND IN THOUGHT-PROVOKING QUESTIONS, IN ANNOTATED BIBLIOGRAPHIES, AND IS REPRESENTED ON A CHART IN TERMS OF "HIGH" OR "LOW DEFINITION", MCLUHAN'S TERMS FOR HUMAN SENSORY RESPONSE TO MEDIA. ALSO REPORTED IN THIS PAPER IS AN EXPERIMENT DESIGNED TO COMPARE EFFECTS OF RADIO, TELEVISION, SPEECH, AND PRINT ON LEARNING. THE SAME FACTUAL MATERIAL (DUPLICATED IN THIS DOCUMENT) WAS PRESENTED IN EACH MEDIUM TO ABOUT 100 COLLEGE UNDERGRADUATES, WHO WERE FULLY INFORMED OF THE EXPERIMENT AND ITS OBJECTIVES PRIOR TO THEIR PARTICIPATION IN IT. ANALYSIS OF VARIANCE OF THE EXPERIMENTAL GROUPS, WHICH WERE HOMOGENEOUS FOR INTELLIGENCE, SHOWED SIGNIFICANT DIFFERENCES IN LEARNING, BOTH IMMEDIATE, AND AFTER EIGHT MONTHS, WITH TELEVISION MOST EFFECTIVE, THEN RADIO, THEN PRINT. CAUTION IN INTERPRETING AND GENERALIZING THESE RESULTS IS URGED. (LH)