Interpersonal Effects on Attitude Formation and Behavior

Based upon precise new measurement techniques derived from a theory of attitude change first utilized by Woelfel and Haller in the study of interpersonal influence, this article attempts to assess the relative effectiveness of major media and interpersonal sources over attitudes toward and actual use of marijuana, a topic which had received considerable media coverage among the populations surveyed prior to and during the research. Based on data from a random sample of 341 students at 3 major U. S. and one major Canadian university, the research indicates (a) that the theory and its implied measurement system is sound, as evidenced by the unusually accurate predictions of both attitude toward marijuana and actual frequency of usage (respectively R = .74 and .89), and (b) that the effects of media are substantially less than those of interpersonal sources, primarily due to the greater relevance of personal information.