Introduction Public Health Communication: Making Sense of Contradictory Evidence
There is a contradiction in the emerging evidence about the effects of public health education and communication on health outcomes. Several large community trials have shown either minimal or no overall effects (COMMIT, 1995; Farquhar et al., 1990; Luepker, 1994; Winkleby, Taylor, Jatulis, & Fortmann, 1996). At the same time, there is substantial evidence coming from observational studies showing that there is major change in health behavior, and also that this behavior change is credibly associated with public health communication, including both deliberate communication programs and normal media coverage of health issues (as described in the other chapters of this volume). This chapter addresses that contradiction, focusing on both evidence and conceptual explanations for the effects. It concludes that the evidence from controlled trials is not adequate, largely because the trials do not produce much difference in exposure. Two possible explanations for the apparent success of some programs are that they achieve a high level of exposure, and they activate a complex process of change in social norms rather than working only to transfer knowledge. A focus on the favorable secular trend of many health behaviors, and on the changes in the public communication environment that have produced and might accelerate those trends, may be an appropriate focus for research and serve as the basis for the design of subsequent interventions.