Media manipulation is an aspect of public relations in which partisans create an image or argument that favours their particular interests. Such tactics may include the use of logical fallacies and propaganda techniques, and often involve the suppression of information or points of view by crowding them out, by inducing other people or groups of people to stop listening to certain arguments, or by simply diverting attention elsewhere.
This is a variant on the traditional ad hominem and bandwagon fallacies applied to entire countries. The method is to discredit opposing arguments by appealing to nationalistic pride or memory of past accomplishments, or appealing to fear or dislike of a specific country, or of foreigners in general. It can be very powerful as it discredits foreign journalists (the ones that are least easily manipulated by domestic political or corporate interests).
The "straw man fallacy" is the lumping of a strong opposition argument together with one or many weak ones to create a simplistic weak argument that can easily be refuted.
A risky but effective strategy summarized best, perhaps, by David Mamet's 1997 movie Wag the Dog, by which the public can be distracted, for long periods of time, from an important issue, by one which occupies more news time. When the strategy works, you have a war or other media event taking attention away from misbehaving or crooked leaders. When the strategy does not work, the leader's misbehavior remains in the press, and the war is derided as an attempted distraction.
This involves using euphemistically pleasing terms to obscure the truth. For example saying "choice" or "reproductive rights" instead of referring to the medical term "abortion", or, similarly, "pro-life" instead of "anti-abortion". A brilliantly executed example was the way that President Lincoln's Emancipation Proclamation prevented European nations from entering the war in support of the Confederacy by framing the war in terms of the moral issue of slavery as opposed to states rights. The concept of "States Rights" was used as justification for the fight against Civil Rights in the 1960s.
By appealing to a real or fictional "consensus" the media manipulator attempts to create the perception that his opinion is the only opinion, so that alternative ideas are dismissed from public consideration. Michael Crichton explains:
Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. Whenever you hear the consensus of scientists agrees on something or other, reach for your wallet, because you're being had.
Let's be clear: the work of science has nothing whatever to do with consensus.
Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant. What is relevant is reproducible results. The greatest scientists in history are great precisely because they broke with the consensus.—
This is a widespread and subtle form of media manipulation: simply giving credence only to "mainstream" sources of information; it exists in many news outlets. Information, arguments, and objections that come from other sources are simply considered "fringe" and ignored, or their proponents permanently discredited, or accused of having their own agenda.
Fear mongering (or scaremongering) is the use of fear to influence the opinions and actions of others towards some specific end. The feared object or subject is sometimes exaggerated, and the pattern of fear mongering is usually one of repetition, in order to continuously reinforce the intended effects of this tactic to frighten citizens and influence their political views. It often states that if something is or is not done, a disastrous event will occur, and that by voting for or against it this can be prevented. The end result is the voter being scared into changing their vote or opinion to one more favorable to the person that is fear mongering.
This is a more general case of distraction by nationalism. Opposing views are ascribed to an out-group or hated group, and thus dismissed out of hand. This approach, carried to extremes, becomes a form of suppression, as in McCarthyism, where anyone disapproving of the government was considered "un-American" and "Communist" and was likely to be denounced.