Evaluations of mass-mediated health campaigns, and mass communications more generally, show that the media typically have only a limited role to play in effecting large-scale change within their audience. In comparison, interpersonal communication, a channel with the least power to reach a mass audience, has been found to produce more individual change. This thesis sought to explore the role of communication channels in effecting health-related change through an integration of social psychology and communication theories.
The impersonal impact hypothesis (Tyler, 1980, 1984; Tyler & Cook, 1984), a psychological account of media effects, predicts that the effects of exposure to health content in the media would typically be limited to changes in impersonal perceptions (i.e., beliefs about others' risk status). Perceptions of personal risk, beliefs that might lead to behaviour change, are instead thought to change only through direct experience with the issue or through exposure to information communicated within informal interpersonal networks. This hypothesis provides some explanation for the limited effects of mass-mediated health campaigns. As a model of media effects, however, the impersonal impact hypothesis is also limited. Subsequent research in this tradition has failed to incorporate insights from communication theories of media influence.
Communication theories emphasize the possibility of observing media effects on individual beliefs, attitudes, and behaviours, at least given certain conditions. Early work on the two-step flow hypothesis (Katz & Lazarsfeld, 1955; Lazarsfeld, Berelson, & Gaudet, 1944) and diffusion of innovations theory (Rogers, 1995; Rogers & Shoemaker, 1971), stresses the dynamic nature of media influence and the connections between mass 6 and interpersonal communication as channels of influence. Parallel work within uses and gratification theory (Katz, Blumler, & Gurevitch, 1974) and media system dependency theory (Ball-Rokeach, 1985, 1998; Ball-Rokeach & DeFleur, 1976) stresses the active and goal-driven aspects of individual media use, and the links between media use and media effects.
The present research sought to incorporate communication processes into the basic impersonal impact hypothesis to provide a more complete understanding of the effects of mass communication on indicators of individual health-related change. Based on an integration of social psychological and communication theories, it was predicted that although media exposure might typically have an impersonal impact, personal impact would also be possible, particularly where (1) media content was linked to individual informational needs, and (2) when media exposure stimulated interpersonal communication.
Five studies were conducted to test these predictions in the context of a variety of health issues (e.g., skin cancer, breast cancer, adolescent drug use) and making use of a variety of methodologies (e.g., pre- exposure post-exposure experimental designs, cross-sectional survey research, and dyadic research). Together these studies demonstrate that post-exposure interpersonal communication about issues presented in media content not only mediates media impact (both within and between people) but also shifts media impact from impersona1 to more personal perceptions. Consistent with social psychological theories of persuasion, the pattern of mediation was related to individual experience with health issues and to individual responses to specific media messages (e.g., evaluations of message quality and emotional reactions to message content).
Consistent with communication theories of media influence, the pattern of mediation was linked to individual media dependencies. In combination, however, the effects of direct experience and individual media dependencies in shaping interpersonal communication and media impact were more complex than was anticipated on the basis of past theorizing and research.
Across the five studies, the pattern of results demonstrates that mass communication is a dynamic process that unfolds over time and that the effects of mass communication are contingent on factors that precede, interact with, and follow specific instances of media exposure. Theoretically, this research demonstrates the value of integrating social psychological and communication theories to provide a more complete picture of the effects of mass-mediated health content on individual health-related beliefs. The implications of these findings are considered in relation to models of communication and change in the specific domain of health, and in relation to study of communication and change within social psychology more generally.