A SERIES OF BRITISH IMPACT STUDIES DEALT WITH ADULT AUDIENCE CHARACTERISTICS (COMPREHENSION, KNOWLEDGE, INTERESTS, ATTITUDES) AND FACTORS WITHIN THE MEDIUM THAT MAKE FOR EFFECTIVE COMMUNICATION. FIVE DIFFERENT TYPES OF SUBJECT MATTER WERE PRESENTED TO MATCHED SAMPLES OF THE GENERAL PUBLIC BY MEANS OF RADIO, TELEVISION, AND PRINTED ARTICLES. THE SUBJECTS WERE TESTED ON COMPREHENSION AND OTHER CAPACITIES, AND THE RESULTS WERE COMPARED WITH DATA ON INTERESTS, EDUCATIONAL ATTITUDES, AND PERSONAL CHARACTERISTICS. ALSO, 64 TELEVISION PROGRAMS WERE TESTED FOR COMPREHENSIBILITY ON SEVEN CONTENT FACTORS. TESTS OF RECOGNITION AND RECALL OF FACTS AND CONCEPTS WERE USED TO ASSESS EFFECTIVENESS OF COMMUNICATION. DIFFERENCES BETWEEN PROGRAMS, AND OCCUPATIONAL LEVELS, (CLOSELY LINKED TO EDUCATION AND INTELLIGENCE), PROVED FAR MORE INFLUENTIAL THAN DIFFERENCES IN MEDIA. THEREFORE, ALTHOUGH INTELLIGENT BUT LESS SOPHISTICATED VIEWERS CAN BENEFIT FROM PERSONALIZED AND DRAMATIZED PRESENTATIONS OF SERIOUS ISSUES, THE ORDINARY BRITON IS UNLIKELY TO SEEK EDUCATIONAL PROGRAMS OUTSIDE HIS HABITUAL VIEWING. (ALSO INCLUDED ARE AN INDEX, APPENDIXES, SIX CHARTS, 53 TABLES, AND NUMEROUS REFERENCES.) THIS DOCUMENT IS AVAILABLE FROM LONGMANS, GREEN AND COMPANY, LTD., 48 GROSVENOR STREET, LONDON W.1, ENGLAND. (LY)