Paul Lazarsfeld and Elihu Katz are well-known as the fathers of functional theory, and their book Personal Influence, published in 1955, is considered to be the handbook to the theory. In researching the effects of the media on the voting public in Elmira, New York in 1940, Lazarsfeld and his team of researchers asked the question as to whether the Hypodermic Needle approach, where (presumably) the mass media would affect the actions of the voting populations, was a valid model of communication. In the 1940s, social researchers needed to question psychologically-based communications theories in an attempt to more clearly define how information flows from a source to its audience. Therefore Lazarsfeld investigated the flow of voting information in Elmira, as well as in Erie County, Ohio, and in the process placed the Hypodermic Needle under the most intense of microscopes.
The specific methods and results of this study were published in Lazarsfeld 's The People's Choice in 1948 (first edition). It is here that functional theory and the Two - Step Flow model of communication are conceived. Stephen W. Littlejohn summarizes the results of the Elmira study nicely:
The researchers found an unexpected occurrence that, although unconfirmed, implied a possible strong involvement of interpersonal communication in the total mass communication process. This effect ... had a major impact on the conception of mass communication (1989, p.262).
Essentially what Lazarsfeld discovered is that many voters regard family members and close personal friends, and not the mass media, as major influences in the decision making process (Lazarsfeld et al 1968, p.vi). These people of influence, who pass on information received in the media to other people in society, were coined opinion leaders. The researchers found that "crystallizers," or those who had a 'don't know' opinion as to who to vote for in October before the 1940 election, tended to vote the way their friends and colleagues voted in November - and thus the presence (and importance) of opinion leaders surged to the forefront (1968, p.xxiv).
Katz and Lazarsfeld pursued this notion of opinion leadership further in a study of the flow of information in Decatur, Illinois in 1945. This is the basis of Personal Influence. Through this research Lazarsfeld and Katz supported their hypothesis that mass media is filtered through what are known as opinion leaders. These opinion leaders tend to "[exert] a disproportionately great influence on the vote intentions of their fellows" (Katz and Lazarsfeld 1955, p.32). Moreover, through the discovery of the concept of opinion leaders, Katz and Lazarsfeld concluded that:
... the traditional image of the mass persuasion process must make room for 'people' as intervening factors between the stimuli of the media and resultant opinions, decisions, and actions (1955, p.32-33).
Interpersonal communication must have a place in communication models, as the presence of such interaction, judging from the conclusions of Katz and Lazarsfeld, is clearly a large factor in determining which messages become publicly accepted and which do not.
Therefore, a visual model of Functional Theory and the Two - Step Flow model of communication would look like this:
Source > Message > Mass Media > Opinion Leaders > General Public
This diagram is based upon a diagram from the home page of Meng Wong at the University of Pennsylvania. To see their site on Communication Models, click here.
To find out more about Katz and Lazarsfeld and their concept of opinion leaders, click here.
