In 1922 Walter Lippman , newspaper columnist, first posed the idea that the mass media shapes public perception with images. Lippman's notion, based on the public's limited first-hand knowledge of the real world, created the foundation for what has come to be known as agenda-setting. The agenda-setting theory maintains the media plays an influential part in how issues gain public attention. Conceptualized over time, agenda-setting is the dynamic process "in which changes in media coverage lead to or cause subsequent changes in problem awareness of issues" (Brosius & Kepplinger, 1990, p. 190; Lang & Lang, 1981). Bernard Cohen's statement in 1963 predicted "the press may not be successful much of the time in telling people what to think, but it is stunningly successful in telling its readers what to think about" (p.13). Whether social or political, local or national, public issues are generated by the media. Consumers not only learn about an issue "but also how much importance is attached to that issue from the amount of information in a news story and its position" (McCombs & Shaw, 1972, p. 176). McCombs and Shaw's study of mediated affects on the 1968 presidential campaign nullified previous assumptions that information and how it is presented has an attitudinal effect inducing behavior changes. Their groundbreaking efforts focused on issue awareness and relevance not behavior and attitude, concluding "the mass media exerted a significant influence on what voters considered to be the major issues of the campaign" (Infante, et al., 1997, p. 366).
Media drives agenda. Funkhouser (1973) focused his attention on the major issues for each year in the 1960s and further concluded that media agenda drives public agenda, and real-world indicators are less strongly associated with issue salience and media attention (Funkhouser, 1973; Dearing & Rogers, 1996). Triggering devices, surmise Cobb and Elder (1972), cue action during a