A paper by W. Lance Bennett and Shanto Iyengar "A new era of minimal effects? The changing foundations of political communication" (pdf) in the Journal of Communication (2008, 58, 707-731) raises the following question: assuming that people are more detached from social institutions that used to provide shared interpretative context and that information channels proliferated and became more individualized, can we say that media effects on people's opinions are minimized and dependent on a largely unknown set of factors?
From p. 708:
As receivers exercise greater choice over both the content of messages and media sources, effects become increasingly difficult to produce and measure in the aggregate while creating new challenges for theory and research.
The authors bring together several strands of research from sociology, political science, and communication to talk about current theoretical debates in the field of political communication and argue for the need to theorize sociotechnical changes that affect modern communication. These sociotechnical changes include selectivity in media source choices, fragmentation of content, and polarization of consumption (seeking sources congruent with one's attitudes and predispositions).
Essentially, this need for theories is framed as a choice between two communication theories - agenda setting theory (media have a large influence on audiences) and the theory of minimal effects (media messages marginally influence the public). To me it seems that the issue is more complex than either of this theories stipulates. But I like the paper's concluding suggestion (along with a set of questions):
Many other areas may benefit from interrupting the pursuit of normal science and thinking about larger democratic implications of a fragmented media environment populated by vastly different audience segments. How do we think about the growing numbers who elude the best efforts to bring them into political debates that do not interest them as much as reality TV, yet who remain critical to election outcomes or legitimation of wars? How shall we think about the solid blocs of 30 or so percent on each end of the spectrum who are actively engaged yet prove unresponsive to most efforts to impart new information, to stimulate deliberative activities, or to deepen concerns about others in society (e.g, the lack of popular engagement with issues such as inequality)? In addition, how can we add ideas about how to involve younger citizens in the interactive life of democracy in ways that enable them to become producers of information rather than just passive consumers of non-credible advertising?
My thinking - more efforts into matching the multiplicity of sources of information with multiplicity of producers, languages, and messages. So far it seems that the hierarchical model of information production and dissemination is slow to change.