The propaganda model according to Edward S. Herman and Noam Chomsky, excerpted from Wikipedia’s article on Chomsky. Emphases mine.
The model attempts to explain this perceived systemic bias of the mass media in terms of structural economic causes rather than a conspiracy of people. It argues that bias derives from five “filters” that all published news must “pass through,” which combine to systematically distort news coverage.
In explaining the first filter, 1)ownership, he notes that most major media outlets are owned by large corporations. The second, 2)funding, notes that the outlets derive the majority of their funding from advertising, not readers. Thus, since they are profit-oriented businesses selling a product—readers and audiences—to other businesses (advertisers), the model expects them to publish news that reflects the desires and values of those businesses. In addition, the news media are dependent on government institutions and major businesses with strong biases as 3)sources (the third filter) for much of their information. 4)Flak, the fourth filter, refers to the various pressure groups that attack the media for supposed bias. 5)Norms, the fifth filter, refer to the common conceptions shared by those in the profession of journalism. (Note: in the original text, published in 1988, the fifth filter was “anticommunism”. However, with the fall of the Soviet Union, it has been broadened to allow for shifts in public opinion.) The model describes how the media form a decentralized and non-conspiratorial but nonetheless very powerful propaganda system, that is able to mobilize an élite consensus, frame public debate within élite perspectives and at the same time give the appearance of democratic consent.
Chomsky and Herman test their model empirically by picking “paired examples”—pairs of events that were objectively similar except for the alignment of domestic élite interests. They use a number of such examples to attempt to show that in cases where an “official enemy” does something (like murder of a religious official), the press investigates thoroughly and devotes a great amount of coverage to the matter, thus victims of “enemy” states are considered “worthy”. But when the domestic government or an ally does the same thing (or worse), the press downplays the story, thus victims of US or US client states are considered “unworthy.”
They also test their model against the case that is often held up as the best example of a free and aggressively independent press, the media coverage of the Tet Offensive during the Vietnam War. Even in this case, they argue that the press was behaving subserviently to élite interests.