The literature on opinion leadership is vast and crosses the borders of many disciplines in the social sciences. The origins of this concept can be traced back to the “two-step flow communication theory” of Katz and Lazarsfeld (1955) and the subsequent multi-step theories (e.g., Robinson, 1976; Windahl, Signitzer & Olson, 1992) that conceptualized opinion leaders as the brokers of information stemming from the mass media and as the filter of this same information to their own network of relations.
The first contributions to the debate on opinion leadership came from sociology, in which interpersonal communication became an autonomous field of study, as distinct from mass communication. In the 1940s the appreciation of interpersonal relations was one of the decisive elements in facilitating the transition from the paradigm of the “powerful mass media” (e.g., the magic bullet theory) to “limited effect” models (McQuail, 1985), such as the above-mentioned “two-step flow of communication” (see Figure 1). It was found, for example, that both the choices of voters in reference to politicians as well as those of consumers in relation to products depended more on interpersonal communication with members of their social network rather than on direct exposure to mass media (Lazarsfeld, Berelson & Gaudet, 1948; Katz and Lazarsfeld, 1955).
From “magic bullet theory” to two-step flow of communication