Firstly, the propaganda model which was initially coined in 1988 by Edward S. Herman and Noam Chomsky could be seen as one of the most significant factors that shakes audiences’ trust. The propaganda model focuses mainly on the media circumstances outside the news organisations and is an ‘institutional critique’ of media behaviour (Herman and Chomsky, 1988: 34). Herman and Chomsky (1988:2) demonstrate that ‘raw material of news’ has to pass through five interacted filters, ‘leaving only the cleansed residue fit to print’. Thereby, they believe this model could help elite dominations to decide which issues and topics are ‘newsworthy’ and appropriate to release, as well as to forbid alternative debate and interpretations. These are five filters of propaganda model argued by Herman and Chomsky (1988):
Due to the trend that many media organisations have been integrated into the market, other institutional sectors such as banks, corporations and even state obtain the opportunities to extend their power in the media field. Therefore, the media content would be biased under the influence of these stockholders. The Walt Disney Company is an instance of media expansion. It is firstly founded as theme park and film production company. Now a number of newspapers and magazines, ABC Television Network and 277 radio stations are owned by Disney (Freepress, 2009). If certain pieces of news released to the public greatly harms the profit and interests of the owners of a news organisation, it will encounter strict censorship and possibly to be filtered.
The significance of advertising is manifest in the field of media. The media companies which could not attract enough advertisers have to raise the price of their products to cover the cost, thus locating themselves in a disadvantage in the market. Therefore, the competition among the news organisations in order to tempt advertisers has become quite drastic in recent decades. They tend to marginalize or even excluded the information which is in contrast of reader's purchasing mood and interests of advertisers. Take News of the World as an example, Paul Mason (2011) mentions that the main cause of its bankruptcy is not only the phone hacking scandal, but also the withdrawing of advertising by large corporations. In this circumstance, large advertisers acted as "unofficial regulators" of News of the World.
The third filter stresses on the reciprocal relationship between news organisations and their sources. It is much more cost-effective to obtain news materials regularly from large corporates and government because such information is routinely recognised. Thus, the news organisations could save the expenses on fact checking. However, Herman and Chomsky