Confirmation Bias is the [[LogicalFallacies fallacy]] of lending extra weight to information and arguments that confirm your own beliefs while disregarding or downplaying evidence that disputes them.

This comes in several forms:
# Seeking evidence for a belief one already holds, or eagerly accepting it, while disregarding or downplaying contradictory evidence.
# Interpreting ambiguous information with a focus on how it favors one's own beliefs.
# Rationalizing contradictory evidence [[IRejectYourReality in a way that still affirms one's own beliefs]].

In fandom, the first of these three types of ConfirmationBias is the most common. Essentially, if a book or any other media product follows a distinct philosophical, political, or religious slant, then people who agree with that slant will often like it despite any flaws it has. Conversely, people who ''disagree'' with its message will often reject it out of hand, regardless of how well written it is.

Keep in mind, however, that many people neither agree or disagree with a message before being presented with an argument that they find convincing. The purpose of many of the examples of this trope can legitimately be said in at least a small part to convince the undecided, rather than change someone's mind. Even so, the ConfirmationBias effect is noticeable.

It is worth noting that even if a work may be not be aimed at converting ideological outsiders, [[WeAREStrugglingTogether that doesn't necessarily mean it's not designed to convert people]].

Also, this does not mean that everyone with a given viewpoint will like a work just because it follows that same view. Some may criticize it for not doing a good enough job persuading those who are undecided or who have the opposite view. Contrast DontShootTheMessage, which is about disliking a work because of its style even if one may agree with its message.
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!!Examples:

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[[folder:Advertising]]

* Any pro-choice/pro-life commercial assumes the message it's giving. IE, an unborn baby is a person and thus abortion is murder = Pro-Life; or they're not a person, and part of the woman thus her decision = Pro-Choice. It's doubtful anyone is ever converted by these, as both very rarely attempt to convince the viewer of the (non)person-hood of the unborn baby.
* Those Mac vs. PC ads that depend entirely on AdHominem and misconceptions to sell their points to the audience, which in most cases either already agrees, disagrees and is already aware of what is untrue about the ads, [[UsefulNotes/{{UNIX}} Took A Third Option]], or is very easily DistractedByTheShiny, which admittedly usually tends to work in Apple's favor.
** The older ads weren't quite as preachy. The newer ones, though...well, they really rely on ViewersAreMorons and what people already hate about Windows (one commercial featured all the PC's walking away and just Justin Long staying after a potential user asked for a computer [[BlatantLies that didn't have any error messages or other problems]]).
** These actually managed to make ''Microsoft Windows'' look like a put-upon underdog. As has been pointed out many times, which of these two men would you hire if they were competing for a job?
*** Notably, the above two elements in particular have combined to make these commercials frequent SnarkBait.
** The T-Mobile parody commercials weren't much better... though T-Mobile was lampooning Apple [=iPhone=], which was at the time an AT&T exclusive.
** The UK versions of the ads are even worse. The Mac and PC are played by Robert Webb and Creator/DavidMitchell, respectively. They play basically the same characters as they do in ''PeepShow'', where Webb's character is stupid, lazy, and unreliable, and Mitchell is hard-working and [[TheComicallySerious serious-to-a-fault]]. Which qualities would you rather have in your computer?
** Samsung has launched a similar ad campaign for their Android mobile devices, portraying Apple users as morons. And they actually ''directly'' attack the same exact potential customers they'd do well to convert. [[SarcasmMode Because we all know how well the Mac vs. PC ads worked.]] Yup, they're even copying Apple's failures. At this rate, soon they'll be rolling out their own maps app that tells you to drive over a lake, through your local library, and onto an airport runway.
* There are several [[PublicServiceAnnouncement PSAs]] that often don't bother persuading those outside of a particular group. It's almost as if the producers are told to produce [=PSAs=] like this.
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[[folder:Film]]

* Pretty much any movie MichaelMoore made. ''Fahrenheit 9/11'' may be the best example.
* The documentary ''Gasland'' about the supposed harm caused by hydraulic fracturing ('Fracking') of rock to mine natural gas. As the ''{{Skeptoid}}'' [[http://skeptoid.com/episodes/4275 podcast points out]], it is hard to know what to make of the movie since it's devoted to proving that fracking is dangerous and generally assumes all of the ill effects to local people (such as tap water that is ''flammable'') are caused by fracking and aren't simply natural phenomena specific to the area. Yet, conversely, most of the high profile criticism of the movie has come from the natural gas industry, so it is very difficult to find un-biased opinion on the subject.
** There's also the fact that towards the end of the movie's production, the critics it was based on who had supposedly proved many of the dangers of fracking were discovered to have been frauds. When asked how the movie was going to address it, it was suggested that in the movie, the fraudulent critics would be portrayed as secretly being in the employ of the companies that would profit from fracking and that they ''allowed'' themselves to be revealed as frauds to discredit fracking critics.

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[[folder:Literature]]

* ''Any'' book that attempts to prove or disprove a certain philosophical or political viewpoint. Reviews on amazon.com for these books tend to be either one star or five stars, due to the reviewers' opinion of the book being so heavily influenced by whether it clashes or not with their personal thoughts. ''The God Delusion'' by RichardDawkins (whose thesis is [[ExactlyWhatItSaysOnTheTin exactly what it sounds like]]) is a notable recent example. Naturally, when Alister [=McGrath=] wrote ''The Dawkins Delusion'' (a book that argues against Dawkins' book), almost anyone who agreed with Dawkins' book automatically disliked [=McGrath=]'s book, whereas those who disagreed with Dawkins' book were almost always immediate fans of [=McGrath=]'s book.
** As with many of these examples, very few actually read them both as noted in the reviews themselves.
** The fact they appealed to people who differed not only in opinion but in the basic ways they see the world and make judgments probably has something to do with it as well.
* On that note, Creator/CSLewis' ''TheChroniclesOfNarnia'' series and PhilipPullman's ''HisDarkMaterials'' series, which are {{author tract}}s for Christianity and nontheism, respectively. Notable in that Lewis didn't originally ''intend'' his work to turn into one, while Pullman ''very much'' intentionally wrote his series with promoting nontheism in mind (as well as making an anti-religious rebuttal to Lewis). As a result, ''HisDarkMaterials'' is a ''lot'' more frank and up-front about its message.
* ''LeftBehind'' is really only liked by people who already believe in the Rapture. And not even all of them.
** Not necessarily; while Christians are the primary readerbase, some people enjoy it regardless of religion.
* Speaking of ''LeftBehind,'' Michael D. O'Brien's ''ChildrenOfTheLastDays'' series has a similar effect, being essentially a Catholic version of the former (sans Rapture). Regardless of the writing, it comes strongest to those who tend to share the author's "traditional Christian" views.
* Much of the writing of libertarian anarchist ScienceFiction author L. Neil Smith falls under this. In fact, he has explicitly stated that he writes mainly to entertain those already having an anti-state worldview.

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[[folder: Live Action Television ]]

* The word "clapter" was coined to describe the latter effect in TV - when an audience applauds a joke more than actually laughing at it. It's an accusation often levelled at the more recent years of ''Series/TheDailyShow''. (Its synonym "clappy humor" has an entry in the [[http://www.urbandictionary.com Urban Dictionary]].)
** There are great honking buttloads of "comedians" who feed on clapter. Not surprisingly, they tend to disappear whenever the political winds shift in their favor.
* ''Series/{{Mash}}'' started with a noticeable anti-war stance, but was still entertaining enough to be enjoyed by someone who disagreed with the show's views. As the series went on, it seemed to become, at least within the show, increasingly required that viewers agree with every line of the Alan Alda Book Of Morality.
* This is undoubtedly one of [[AuthorTract two reasons]] that TheOReillyFactor and CountdownWithKeithOlbermann exist. By extension, any show (or book, or radio program, or ''whatever'') with a severe political slant is going to fall into this at some point. There's almost no pundit who doesn't.
* Panel shows try to avert this by having a variety of guests of different viewpoints (mainly because it would be boring to see a bunch of people sitting around agreeing on everything). Of course, there are plenty of ways to make a biased panel show (i.e. get a FoxNewsLiberal, stack the deck by putting [[ChewbaccaDefense aggressive "strong" debaters]] against lesser experienced ones, unevenly stack the panel on one side so [[QualityByPopularVote everyone can gang up on the minority opinion]], etc.)
* On ''Series/SaturdayNightLive'' in 2012, SethMeyers recommended that both presidential candidates stop "telling us stories about people you met at your rally who ''happen'' to agree with your positions. That's like Bret Michaels saying, 'At my last concert, someone yelled '{{Music/Poison}} rules!'"
* Totally Biased With W. Kamau Campbell: Most, if not all, of the political jokes are funny if you agree with the guy. This tropes applies even more so for almost all of the guests, the exception being Creator/ChrisRock.
* Television news stations. You can pretty accurately determine the political leanings of a person by what network they watch. Obviously, the pundits that are saying what you believe are the ones that "really get it" and "tell it like it is without all the crap."
* JoeDante has a bad tendency to do this in his TV work. This lead to the latter half of Eerie Indiana being unwatchable by anyone who wasn't a capital-L liberal.
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[[folder:Music]]

* [[DeadHorseGenre Certain genres of music]] may fall into this trope, particularly those that began as underground movements and became mainstream later on; artists and songs would be judged primarily on their subject matter, perceived attitude, or whether or not a message is present, rather than being enjoyed/loathed for the music itself. Hip hop music, due to its lyric-heavy, melody-sparse nature, might be the most prominent example. Particularly the artists of the PoliticalRap sub genre. The main polarizers being PublicEnemy, TheCoup, and the extremely controversial rappers Paris, and Immortal Technique. And to a lesser extent, Ice Cube, IceT, and TupacShakur.
** Also affected are genres which rely on a particular philosophy: Things like [[ThreeChordsAndTheTruth Punk]] and BlackMetal come to mind.

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[[folder: Newspaper Comics ]]
* Politically themed comic strips, from ''{{Doonesbury}}'' to ''MallardFillmore'' to ''PricklyCity'' to ''TheBoondocks'': if you agree with them, they're hilarious; if you don't, they're poison to the mind. If you have no bias one way or another, then you're probably just skipping over them all to see what ''ComicStrip/{{Frazz}}'' is up to today.
** Ditto for ''The Brilliant Mind of Edison Lee''. It's questionable if even the people it's allegedly preaching to find it funny. Comments on the comics SnarkBait blog [[http://www.joshreads.com The Comics Curmudgeon]] seem to indicate not...
** And ''I Drew This'', by the ''Webcomic/OzyAndMillie'' lady.
** ''The Bad Reporter'' wasn't originally this -- a cartoon from the early 2000s mocked the "comic-book-ization" of the media and argued that both sides of the political aisle were engaging in {{demonization}}, without particularly insulting the followers of either side so much as their leaders. A cartoon a few years later parodied ''IAmSam'' with undecided voters in place of the mentally retarded. Not trying to win any converts now, are we, Mr. Asmussen?
** Same goes for "alt-comic" strips like ThisModernWorld, which are placed on weekly/monthly free newspapers for a certain city that have a significant liberal population.
* ''MinimumSecurity'' was mostly only published in alternative newspapers where extreme views are more common. As such, it is no surprise to see a comic strip where everyone ranging from religious people, scientists, businessmen, and people who simply eat meat are depicted as evil and stupid. The main character doesn't eat meat and advocates the destruction of society, thus, she is smarter.
* Dog-themed comics like ''Fred the Basset'' and ''Marmaduke'' tend to be praised by dog lovers and disliked by all others. ''Pluggers'' is loved by self-identified Pluggers (many of the comic ideas are sent in by readers) while people outside the demographic find the jokes incomprehensible. A similar trend follows for any other heavily themed comic.

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[[folder:Radio]]

* Most political radio shows tend to be this by default. NealBoortz does his best to encourage dissenting opinions, for certain values of "encourage" and "dissenting" and "his best", because (as he said in his book ''Somebody's Gotta Say It'') shows where everybody agrees with the host tend to be extremely boring and sycophantic.
* ''TheNowShow'' can veer into this territory, although it's usually more about cynicism of ''any'' politician or celebrity than about conservatives and liberals.
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[[folder: Stand Up Comedy ]]

* JeffDunham's schtick with "Walter", a puppet who often voices Midwestern conservative views, is partly made up of "clappy humor," though mostly done to appeal to audience members who "know someone like this".
** Though Walter seems to be set up so that those who agree with him can laugh with him, and those who disagree with him can laugh ''at'' him; he's not exactly portrayed as a happy, admirable, or attractive individual after all. Obviously those who tend towards an extreme of either won't laugh at all.
* GeorgeCarlin was a master of clappy humor too. His act came to focus more and more on his general misanthropy and criticism of optimistic people regardless of political affiliation. His last tour especially played up the "grumpy old man" angle.
* WandaSykes's standup routine is a fairly painful example of this.
* Much of LewisBlack's material pre-2009 was essentially a liberal critique of the Bush administration, individuals within it, and cultural conservatives paired with over the top facial expressions and screaming in reaction to those things. Hilarious IF you are a culturally liberal person; childish and grating if you aren't.
* BillMaher falls under this, hard. His highly political material, paired with his tendency to try to be edgy make him a very divisive comic prone to clapter/criticism depending on who's watching.
* RichardPryor spots 'Clapter' and calls it out in ''Live On the Sunset Strip'' when his mention of Arizona State Penitentiary gets an applause; "What? You're applauding that? Arizona State Penitentiary real popular?!"
* BillyConnolly also gets exasperated on his "Live in New York" DVD by this. He begins his set by saying wearily "I'm supposed to talk about Scotland all the time" and is driven to distraction by the American crowd constantly clapping ''any'' mention of Scottish towns and cities.
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[[folder:Other]]

* The ''ComicBook/ChickTracts'', although most of those with the same slant think he's insane.
* Tony Kushner not only admitted to, but ''defended'' this in [[http://www.jstor.org/stable/4337551?seq=10 a 1997 essay]]:
-->-- ''The converted need preaching to as much as the unconverted, and will usually prove far more responsive and interested in change . . . Those who are involved in the struggle to change the world need art that assists in examining the issues at hand, which are usually incredibly complex.''
* Some critics have argued that the internet would result in "echo chambers" where everyone would just view news sites, blogs, and forums that didn't challenge their views. However, according to one [[http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1588920 study]], the "echo chamber" isn't any worse than any other media (Since radio, TV and print media that pander to either side do exist and always have).
* Played with in regards to Website/YouTube videos about conspiracy theories. There will be a few instances where the title points in one direction, but the content points another direction, and sometimes there will be an admission that this is done to draw in the opposing crowd.
* This trope is simply a ubiquitous feature of the human cognitive landscape. Rigorous logic and academic thinking helps to mitigate this very human flaw.
* This trope is way more common in academia and directed research than anyone is comfortable with admitting, let alone tackling.
* A major contributor to the continued appeal of psychics and mediums. As Michael Shermer has noted, they don't tend to give out negative readings or tell people things they ''don't'' want to hear:
--> There was redemption for all - our loved ones forgive us for any wrongdoing; they still love us; they suffer no more; they want us to be happy. What else would he say? "Your father wants you to know that he will never forgive you for wrecking his car"? (On James Van Pragh)
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