Katz, Elihu/Lazarsfeld, Paul F. (1955): Personal Influence. The Part Played by People in
the Flow of Mass Communication. New York: Free Press.
[English translation of Hepp, A. (2019) Katz, E. / Lazarsfeld, P. F. (1955): Personal Influence. The Part Played by
People in Mass Communication. In Schlüsselwerke der Netzwerkforschung [Key Works of Network Analysis], (Eds,
Holzer, B. & Stegbauer, C.) Springer VS, Wiesbaden, pp. 293-296.]
Personal Influence is one of the most influential and most regularly cited piece of American
mass communication research written in the post-war period. It is the sequel to a study carried
out by Paul Lazarsfeld et al. (1944) on the influence of media coverage on the presidential
elections of 1940 (for further context, see Lazarsfeld and Merton in 1964). The book emerged
from a 1944 journal-funded research project that set out to investigate media influence on
women's decision-making in Decatur, Illinois. Several other researchers were involved in the
empirical investigation, including C. Wright Mills. Elihu Katz’s contribution enriched the study
with an extensive literature review on group sociological research that introduced the concept
of the ‘interpersonal network’ (pp. 82-115). The second part of the publication presents the
results from the Decatur empirical study on peer group ‘opinion leaders’ and the role they play
in decision-making. While the two parts complement each other very well, the authors self-
critically note that rather than forming a fully integrative analysis the should be considered as
companion pieces (p. 12). Personal Influence takes a stand against the mass communication
research of the day which, Katz and Lazarsfeld argue, short-sightedly understands media
impact as a direct influence of media content on socially isolated individuals. By contrast, as
demonstrated by the book’s subtitle, the authors emphasize the ‘part played by people’ (p. 13)
in the flow of mass communications and in so doing reoriented media and communications
research for decades to come.
Katz and Lazarsfeld’s central argument hinges on what they refer to as ‘the two-step flow of
communication’ which maintains that the influence media content has does not unfold in a
direct manner. Instead, influence is exerted or mediated through the personal networks in
which people are embedded and the communication that takes place within them. Through
this process, individuals they refer to as ‘opinion leaders’, that is, individuals who provide
interpretations of everyday life as well as current events that orientate others, play a prominent
role. This thesis is justified in two ways: theoretically in the first part of the book and empirically
in part two.
In theoretically justifying part one, Katz and Lazarsfeld draw attention to a fundamental
connection between interpersonal relationships and communication networks (p. 44): On the
one hand, interpersonal relationships operate as an anchor point for individual opinions,
attitudes, habits and values. On the other, these interpersonal relationships imply networks of
interpersonal communication. In essence, Katz and Lazarsfeld are not simply interested in
social networks in general but rather the influence communication networks have on
interpersonal relationships and the opinions and attitudes anchored within:
It is our guess that these two characteristics of small, intimate groups – (1) person to
person sharing of opinions and attitudes (which we often shall refer to as group norms)
and (2) person-to-person communications networks – are the keys to an adequate
understanding of the intervening role played by interpersonal relations in the mass
communications process. (p. 45)
Their empirical study of the ‘two-step flow of communication’ in part two of the book is based
on a snowball sampling technique of follow-up interviews. This approach broke new
methodological ground. To this day, their methodological innovation is still tangible in the
detailed appendix, included in the book, in which the problems of the procedure are discussed
in detail. The aim of the follow-up interviews, which were later used more widely in network
research, was, on the one hand, to verify whether the interpersonal communication mentioned
in the first interview took place the way it was described. On the other hand, the follow-up
interviews were used to help determine whether or not, and if so, in which ways, interpersonal
communication had an ‘influence’ on decision making processes (p. 355). The study’s analysis
was drawn from around 800 interviews. They focused on four areas of everyday decision-
making: marketing, fashion, (local) public affairs, and visits to the cinema.
The main result of their analysis was that in almost 60% of decisions made no other person
was remembered as being relevant to the decision-making process as decisions were
generally made alone and, at times, these decisions were influenced by mass media. In
approximately 40% of decisions made, however, certain discussions were mentioned that
were identified as relevant to the decision-making process. Family members and friends were
typically mentioned as communication partners (p. 142-143). In this way they were able to
identify particular relationships between opinion leaders (‘influentials’) and those who orientate
themselves toward them (‘influencees’). The study found that opinion leadership is domain-
specific: opinion leaders and the patterns of the opinion leadership they engage in differ in the
areas of marketing, fashion, public affairs, and films. The opinion leaders are ‘experts’ in their
respective area and are asked for advice by other members of their communication networks
in the course of everyday life.
Katz and Lazarsfeld revealed that opinion leaders can be found within different educational
groups, that they are particularly sociable people, and that they have many social contacts.
Across the various educational groups, opinion leaders were found to use more media than
those who orient themselves towards them and that they used these media as an important
information source (p. 310). These opinion leaders then passed on their knowledge to others
in their personal networks as if they were the foundation of their opinions and attitudes. This
is the essential nature of the ‘two-step flow of communication’.
In a moment of reflexivity, however, the two authors criticize their own investigation as they
did not fully grasp this “flow of communication” as they could only describe isolated ‘influential-
influencee’ relationships (p. 309). In order to adequately understand the two-step flow of
communication, a full investigation of an entire network within a municipality would have been
necessary. In looking back at the study in the present day, however, it is clear that this ‘ideal’
of analysing an entire network is difficult to realize.
In examining Personal Influence’s reception and the impact it had on the field, it should be
noted, as already mentioned above, that this is one of the most influential and frequently cited
American studies of media and communications research of the post-war era. Reviews from
the time heralded the work as a ‘major contribution to our understanding of the communication
process’ (Eagle 1957: 176), and as a ‘brilliant’ theoretical contribution (Riley 1956: 355). From
a methodological point of view, the reflexivity harnessed in their approach was considered
exemplary. Overall, the study’s contribution to media and communications research consists
first of all in having dissolved the dominant theory that there exists one homogeneous
audience. According to Katz and Lazarsfeld’s thesis, personal influences in social groups and
their communication networks have the potential to be more significant than mass media
content. It is important, therefore, to consider the social context of media use if one wants to
imply an argument related to media content’s influence. For this approach, the study provided
a theoretical and empirical framework to consider the internal structure of groups as well as
the subsequent communication about media content in any analysis of media and
From a network research perspective, Katz and Lazarsfeld’s book forms an early connection
between media and communications research and network analysis as the two authors sought
to capture the idea of opinion leadership as supported by media use in group (communication)
networks (see Schenk 1995: 6- 13; see also Schenk 1984). Nevertheless, it is precisely at this
point that the gaps between the theoretical and empirical sections of the study noted by Katz
and Lazarsfeld are revealed. The empirically valid combination of network analysis and
research on opinion leadership would only succeed in later studies.
Personal Influence should be considered as the starting point for a long-standing tradition in
media and communications research that, among others, Elihu Katz has worked to develop
(see Katz 1957, as an overview Okada 1986 and Robinson 1976). To this day, even as our
media environment has become rapidly and increasingly more complex, Personal Influence
remains an important reference point for understanding the relationships between public
engagement, social groups, and personal communication (Couldry and Markham, 2006; Watts
and Dotts, 2007) by opening up a differentiated view of what was previously only vaguely
described as a mass audience.
Translation: Jeanette Asmuss & Marc Kushin
Adler, K. P. (1957). Elihu Katz and Paul F. Lazarsfeld. Personal influence: The part played by
people in the flow of mass communication. The Annals of the American Academy of
Political and Social Science 309, 176 – 177.
Couldry, N. & Markham, T. (2006). Public connection through media consumption: between
oversocialization and de-socialization. The Annals of the American Academy of Political
and Social Science 608, 251 – 269.
Katz, E. (1957). The two-step-flow of communication. An up-to-date report on a hypothesis.
Public Opinion Quarterly 21, 61 – 78.
Lazarsfeld, P. F., Berelson, B. & Gaudet, H. (1944). The People’s Choice New York: Free
Press. Okada, N. (1986). The process of mass communication: a review of studies on
the two-step flow of communication hypothesis. Studies of Broadcasting 22, 57 – 78.
Riley, J. W., Katz, E. & Lazarsfeld, P. F. (1956). Personal influence: The part played by people
in the flow of mass communication. Public Opinion Quarterly 20, 355 – 356
Robinson, J. P. (1976). Interpersonal influence in elections campaigns: the two- step flow
hypothesis. Public Opinion Quarterly 40, 304 – 19.
Watts, D. J & Dodds, P. S. (2007). Influentials, networks, and public opinion formation. Journal
of Consumer Research 34, 441 – 458.