After introducing agenda setting and priming , I want to complete the "holy trinity of media effects" with a short introduction of framing, which I consider to be the most important effect of this threesome. Whereas agenda setting tells us what to think about (by putting issues on the public agenda), framing tells us how and why to think about an issue. To frame means to communicate in a way that leads audiences to see something in a certain light or from a particular perspective. Aspects that are not included in the frame do not come to the audience's attention. Framing determines where the audience puts its attention. Effective framing taps into preexisting beliefs, attitudes, and opinions; it highlights certain aspects of an issue over other aspects.
The topic of climate change is a great example of how message framing can alter public opinion. For instance, replacing the term “global warming” with the broader term “climate change” expanded the topic and enabled people to consider different aspects of the issue. Because different aspects call for different solutions, opportunities were opened to address a range of relevant factors. The phenomenon of "climate change" can further be framed as "ice caps melting" or "preventing the next ice age." Very different meanings for the same phenomenon that would require very different reactions.
The media are somewhat known for negative framing , for putting a negative spin on news because otherwise it wouldn't be newsworthy: If it bleeds it reads. For example, a study by Pratt, Ha, and Pratt (2002)  of the representation of diseases in the media in Africa showed that the media often used negative and derogatory descriptions when reporting on diseases such as HIV/AIDS. In contrast, they used no negative terms or examples and no derogatory language in reporting on diseases such as tuberculosis. As a consequence of the way in which the media framed the topic in a negative light, it is likely that people with HIV/AIDS were seen in a negative way by people who heard or read the reports. Tuberculosis patients were more likely to have received sympathy from those same people.
There are many different frames, some of which I want to at least mention. When news is reported in the form of specific events or particular cases, the framing is episodic. Citizens receiving episodic reports are less likely to consider society responsible for the events, and more likely to think that individuals are responsible. In contrast, when political issues and events are presented in a general or collective context, the framing is thematic. Citizens receiving thematic reports are less likely to hold individuals accountable, and more likely to believe that society is responsible. Research has shown that when citizens viewed media stories about poverty featuring homeless or unemployed people (episodic framing), they were more likely to blame poverty on individual failings, such as laziness, or on low levels of education. Those people who viewed media stories about high national rates of unemployment or poverty (thematic framing), however, were less likely to place blame on individual failings; instead, they attributed responsibility to governmental policies and other factors beyond the victims’ control (see Iyengar 1991 ).
A news story that focuses on describing a specific problem or policy has an issue frame. A strategic frame emphasizes the process by which something happens. For instance, putting an issue frame on the topic of corruption would entail explaining how much corrupt behavior occurs in a specific country and sector, who the typical culprits are, and so forth. Putting the topic in a strategic frame would require looking at the roots of corruption, why it occurs, in what forms it occurs, and what can be done to fight it. In some research studies, strategic framing prompted cynicism among the audience. News reports that showed “the game of politics”—strategic discussions and arguments between politicians and experts rather than real issues—made the audience more weary of both politics and politicians (see Cappella and Jamieson 1997 ).
Agenda setting and priming are mainly salience effects, i.e. they bring certain issues to our attention. This alone does not shape public opinion. A salient issue must also stand for something, it must have a context that lets us integrate it into our existing cognitive schemata. The media can make us think about a great number of things, but it is the frame that makes them relevant in terms of shaping public opinion. Legendary media scholars Kurt and Gladys Lang argue that when the media tell us what to think about they also tell us how to think about it. In order for us to think about an issue we need to know why we should think about it. In explaining why, the media already provide a certain context. This is why framing is so important: The essential difference is not whether we think about unemployment or national security when we cast our vote, the essential difference is whether we think of censorship as a means to protect national security or as a violation of human rights.