THIS STUDY DEALS WITH COMMUNICATION AT THREE LEVELS--DEVELOPMENT OF A GENERALIZED MODEL OF THE PROCESS WHEREBY COMMUNICATION ACHIEVES IMPACT, THE OPERATIONALIZATION OF THE MODEL, AND TESTING OF THE DEGREE TO WHICH THE MODEL PREDICTS THE RESPONSE OF MEMBERS OF THE POTENTIAL AUDIENCE TO A SPECIFIC COMMUNICATION EVENT. THIS IMPACT MODEL TAKES THE CONTENT AND INTENT OF THE MESSAGE AS GIVEN AND EXAMINES RESPONSES OF THE TOTAL POTENTIAL AUDIENCE. A BASIC UNDERLYING NOTION IS THAT IN RECEIVING AND RESPONDING TO A MESSAGE THE READER MUST PERFORM SEVERAL FUNCTIONS. THESE FUNCTIONS CAN BE LOGICALLY INTERPRETED INTO A FLOW OF ACTION INVOLVING A SERIES OF COMMUNICATION FILTERS--ATTENTION, COMPREHENSION, AND ACCEPTANCE. ANOTHER BASIC NOTION IS THAT THE RESPONSE AT ANY GIVEN STAGE IS NOT RANDOM, BUT PRECONDITIONED BY THE RECEIVER'S PREVIOUS EXPERIENCE AND BY WHAT HE PERCEIVES TO BE HIS INTEREST. THE EVENT ANALYZED IS THE MIDWEST COUNTY CIVIL DEFENSE EXHIBIT. FINDINGS STRONGLY SUPPORT THE NOTIONS INCLUDED IN THE IMPACT MODEL. IMPLICATIONS OF THESE FINDINGS FOR CIVIL DEFENSE COMMUNICATION ARE DRAWN. THIS DOCUMENT INCLUDES TABLES, FIGURES, AND 89 REFERENCES AND IS AVAILABLE, AD-657-217, FROM THE CLEARINGHOUSE FOR FEDERAL SCIENTIFIC AND TECHNICAL INFORMATION, SPRINGFIELD, VA. 22151, MICROFICHE $0.65, HARDCOPY $3.00. (AUTHOR/LY)