Hostile media effect
The hostile media effect, originally deemed the hostile media phenomenon and sometimes called hostile media perception, is a perceptual theory of mass communication that refers to the finding that people with strong biases toward an issue (partisans) perceive media coverage as biased against their opinions, regardless of the reality. Proponents of the hostile media effect argue that this finding cannot be attributed to the presence of bias in the news reports, since partisans from opposing sides of an issue perceive the same coverage differently. The hostile media effect illustrates notions of the active media audience, in demonstrating that audiences do not passively receive media content but instead selectively interpret it in light of their own values and predispositions. Despite journalists’ best intentions to report news in a fair and objective way, partisans are motivated to see neutral content as harboring a hostile bias. The phenomenon was first proposed and studied experimentally by Robert Vallone, Lee Ross and Mark Lepper.
In 1982, the first major study of this phenomenon was undertaken; pro-Palestinian students and pro-Israeli students at Stanford University were shown the same news filmstrips pertaining to the then-recent Sabra and Shatila massacre of Palestinian refugees by Christian Lebanese militia fighters in Beirut during the Lebanese Civil War. On a number of objective measures, both sides found that these identical news clips were slanted in favor of the other side. Pro-Israeli students reported seeing more anti-Israel references and fewer favorable references to Israel in the news report and pro-Palestinian students reported seeing more anti-Palestinian references, and so on. Both sides said a neutral observer would have a more negative view of their side from viewing the clips, and that the media would have excused the other side where it blamed their side.
Subsequent studies have found hostile media effects related to other political conflicts, such as strife in Bosnia. and in U.S. presidential elections., as well as in other areas, such as media coverage of the South Korean National Security Act, the 1997 United Parcel Service Teamsters strike, genetically modified food, and sports.
This effect is interesting to psychologists because it appears to be a reversal of the otherwise pervasive effects of confirmation bias: in this area, people seem to pay more attention to information that contradicts rather than supports their existing views. This is an example of disconfirmation bias.
An oft-cited forerunner to Vallone's et al. study was conducted by Albert Hastorf and Hadley Cantril in 1954. Princeton and Dartmouth students were shown a filmstrip of a controversial Princeton-Dartmouth football game. Asked to count the number of infractions committed by both sides, students at both universities "saw" many more infractions committed by the opposing side, in addition to making different generalizations about the game. Hastorf and Cantril concluded that "there is no such 'thing' as a 'game' existing 'out there' in its own right which people merely 'observe.' ... For the 'thing' simply is not the same for different people whether the 'thing' is a football game, a presidential candidate, Communism, or spinach."
- Selective recall refers to memory and retrieval. In instances of the hostile media effect, partisans should tend to remember more of the disconfirming portions of a message than the parts that support their position, in a variation of the negativity effect. Vallone and his colleagues observed selective recall differing along partisan lines even on simple, objective criteria such as the number of references to a given subject. However, numerous studies have documented the hostile media effect even when selective recall is positive rather than negative.
- Selective Perception refers to the process by which individuals perceive what they want to in media messages while ignoring opposing viewpoints. In instances of the hostile media effect, partisans have a heightened tendency to interpret aspects of a message as unfavorable - or hostile - as opposed to categorizations by non-partisans. In other words selective perception is a form of bias because we interpret information in a way that is congruent with our existing values and beliefs. 
- The different standards explanation or Motivated reasoning refers to the validity of arguments. This is confirmation bias taken to the next level. It leads people to confirm what they already believe, while ignoring contrary data. But it also drives people to develop elaborate rationalizations to justify holding beliefs that logic and evidence have shown to be wrong. Motivated reasoning responds defensively to contrary evidence, actively discrediting such evidence or its source without logical or evidentiary justification. It seems to be assumed by social scientists that motivated reasoning is driven by a desire to avoid cognitive dissonance. It suggests that reason partisans are so prone to see an unbiased message in a hostile light is because of the strength of the favorable argument they have built in their minds over time. Rather than seeing confirmation bias as an opposite force of hostile media effect, the different standards explanation sees it as a contributing force. As Vallone et al. noted in the seminal study:
- "Partisans who have consistently processed facts and arguments in light of their preconceptions and prejudices […] are bound to believe that the preponderance of reliable, pertinent evidence favors their viewpoint. Accordingly, to the extent that the small sample of evidence and argument featured in a media presentation seems unrepresentative of this larger “population” of information, perceivers will charge bias in the presentation and will be likely to infer hostility and bias on the part of those responsible for it." 
It is important to note that these criteria allow for specific measures beyond subjective generalizations about the media coverage as a whole, such as what might be expressed as "I thought that the news has been generally biased against this side of the issue." The research suggests the hostile media effect is not just a difference of opinion but a difference of perception (selective perception).
Source Factors 
Characteristics of the message source may also influence the hostile media effect. A source perceived to be friendly to the partisan (usually because of agreeable ideology or geographic proximity to the group) is less likely to invoke the hostile media effect than a source that is disagreeable or geographically detached. In numerous studies, Albert C. Gunther and his associates have suggested that the ability of mass media to reach a large audience is what triggers the hostile media effect. Consistently, they found that a message appearing to originate from a newspaper was perceived as hostile by partisans, while an identical message appearing in a student essay was perceived as unbiased, or even favorable toward the partisan cause.
All of these explanatory mechanisms are influenced by partisanship. From the first studies, the hostile media effect has required an audience of partisans, with stronger beliefs correlating with stronger manifestations of the effect. Increasing devotion to a particular side of an issue leads to increasing levels of biased information processing, whether out of protection of personal values or a strong sense of group affiliation.
Relative Hostile Media Effect 
Early hostile media effect studies measured perceptions of a media message designed to be unbiased. As ideologically diversified news outlets became more commonplace, later experiments began to utilize messages that were less objective. They found that while partisans on both sides of an issue recognized the bias, the group the message opposed perceived a greater degree of bias than the group the message supported. This variation is referred to as the relative hostile media effect, and has been demonstrated in media coverage of the use of primates for lab testing, as well as in partisan perceptions of The O'Reilly Factor and The Daily Show with Jon Stewart.
See also 
- Cognitive bias
- Confirmation bias
- Bias blind spot
- List of cognitive biases
- Self-serving bias
- Selective perception
- Media bias
- Selective exposure theory
- Vallone, R.P., Ross, L., & Lepper, M.R. (1985). The hostile media phenomenon: Biased Perception and Perceptions of Media Bias in Coverage of the "Beirut Massacre". Journal of Personality and Social Psychology, 49, 577-585. summary.
- Vallone, R.E., Lepper, M.R., & Ross, L. (1981). Perceptions of media bias in the 1980 presidential election. Unpublished manuscript, Stanford University. As cited in Vallone, Ross & Lepper, 1985.
- Matheson, K. & Dursun, S. (2001). Social identity precursors to the hostile media phenomenon: Partisan perceptions of coverage of the Bosnian conflict Group Processes and Intergroup Relations, 4, 117-126.
- Dalton, R. J.; Beck, P. A.; Huckfeldt, R. (1998). "Partisan Cues and the Media: Information Flows in the 1992 Presidential Election". American Political Science Review 92 (1): 111–126. JSTOR 2585932.
- Choi, J.; Park, H.S., Chang, J.C. (2011). "Hostile media perception, involvement types, and advocacy behaviors". Journalism & Mass Communication Quarterly 88 (1): 23–39. doi:10.1177/107769901108800102.
- Christen, C.T.; Kannaovakun, P.; Gunther, A.C. (2002). "Hostile media perceptions: Partisan assessments of press and public during the 1997 United Parcel Service strike". Political Communication 19 (4): 423–436. doi:10.1080/10584600290109988.
- Gunther, A.C.; Liebhart, J.L. (2006). "Broad reach or biased source? Decomposing the hostile media effect". Journal of Communication 56 (3): 449–466. doi:10.1111/j.1460-2466.2006.00295.x.
- Gunther, A.C.; Schmitt, K. (2004). "Mapping boundaries of the hostile media effect". Journal of Communication 54 (1): 55–70. doi:10.1111/j.1460-2466.2004.tb02613.x.
- Arpan, L.M.; Raney, A.A. (2003). "An experimental investigation of news source and the hostile media effect". Journalism & Mass Communication Quarterly 80 (2): 265–281. doi:10.1177/107769900308000203.
- Hastorf, A. H.; Cantril, H. (1954). "They Saw a Game: A Case Study". Journal of Abnormal and Social Psychology 49 (1): 129–134. doi:10.1037/h0057880.
- Hastorf & Cantril (1954), pp. 132-133. Emphasis as in original.
- Giner-Sorolla, R.; Chaiken, S. (1994). "The causes of hostile media judgments". Journal of Experimental Social Psychology 30 (2): 165–180. doi:10.1006/jesp.1994.1008.
- Vallone et al., 1985, p. 579
- Reid, S.A. (2012). "A self-categorization explanation for the hostile media effect". Journal of Communication 62 (3): 381–399. doi:10.1111/j.1460-2466.2012.01647.x.
- Gunther, A.C.; Miller, N.; Liebhart, J.L. (2009). "Assimilation and contrast in a test of the hostile media effect". Communication Research 36 (6): 747–764. doi:10.1177/0093650209346804.
- Gunther, A.C.; Chia, S.C. (2001). "Predicting pluralistic ignorance: The hostile media perception and its consequences". Journalism & Mass Communication Quarterly 78 (4): 688–701. doi:10.1177/107769900107800405.
- Coe, K.; et al. (2008). "Hostile news: Partisan use and perceptions of cable news programming". Journal of Communication 58 (2): 201–219. doi:10.1111/j.1460-2466.2008.00381.x.