Anti-denialist banner at the 2017 Climate March in Washington, D.C.
In the sciences and in historiography, denialism is the rejection of basic facts and concepts that are undisputed, well-supported parts of the scientific consensus or historical record on a subject, in favor of ideas that are radical, controversial, or fabricated. Examples include Holocaust denial, AIDS denialism, and climate change denial. The forms of denialism present the common feature of the person
rejecting overwhelming evidence and trying to generate political controversy in attempts to deny the existence of consensus.
In psychology, denialism is a person's choice to deny reality as a way to avoid believing in an uncomfortable truth. Denialism is an essentially irrationalhuman behavior that withholds the validation of a historical experience or event when a person refuses to accept an empirically verifiable reality.
The motivations and causes of denialism include religion, self-interest (economic, political, or financial), and defence mechanisms meant to protect the psyche of the denialist against mentally disturbing facts and ideas; such disturbance is called cognitive dissonance.
Definition and tactics
Anthropologist Didier Fassin distinguishes between denial, defined as "the empirical observation that reality and truth are being denied", and denialism, which he defines as "an ideological position whereby one systematically reacts by refusing reality and truth". Persons and social groups who reject propositions on which there exists a mainstream and scientific consensus engage in denialism when they use rhetorical tactics to give the appearance of argument and legitimate debate, when there is none. It is a process that operates by employing one or more of the following
five tactics to maintain the appearance of legitimate controversy:
Conspiracy theories – Dismissing the data or observation by suggesting opponents are involved in "a conspiracy to suppress the truth".
Cherry picking
– Selecting an anomalous critical paper supporting their idea, or using
outdated, flawed, and discredited papers to make their opponents look
as though they base their ideas on weak research. Diethelm and McKee
(2009) note, "Denialists are usually not deterred by the extreme
isolation of their theories, but rather see it as an indication of their
intellectual courage against the dominant orthodoxy and the
accompanying political correctness."
False experts
– Paying an expert in the field, or another field, to lend supporting
evidence or credibility. This goes hand-in-hand with the marginalization
of real experts and researchers.
Moving the goalposts
– Dismissing evidence presented in response to a specific claim by
continually demanding some other (often unfulfillable) piece of evidence
(aka Shifting baseline)
Common tactics to different types of denialism include misrepresenting evidence, false equivalence, half-truths, and outright fabrication.South African judge Edwin Cameron
notes that a common tactic used by denialists is to "make great play of
the inescapable indeterminacy of figures and statistics". Historian Taner Akçam
states that denialism is commonly believed to be negation of facts, but
in fact "it is in that nebulous territory between facts and truth where
such denialism germinates. Denialism marshals its own facts and it has
its own truth."
Focusing on the rhetorical tactics through which denialism is achieved in language, in Alex Gillespie (2020)[17] of the London School of Economics
has reviewed the linguistic and practical defensive tactics for denying
disruptive information. These tactics are conceptualized in terms of
three layers of defence:
Avoiding – The first line of defence against disruptive information is to avoid it.
Delegitimizing – The second line of defence is to attack the messenger, by undermining the credibility of the source.
Limiting – The final line of defence, if disruptive information
cannot be avoided or delegitimized, is to rationalize and limit the
impact of the disruptive ideas.
In 2009, author Michael Specter
defined group denialism as "when an entire segment of society, often
struggling with the trauma of change, turns away from reality in favor
of a more comfortable lie".
Prescriptive and polemic perspectives
If one party to a debate accuses the other of denialism they are framing the debate. This is because an accusation of denialism is both prescriptive and polemic: prescriptive because it carries implications that there is truth to the denied claim; polemic since the accuser implies that continued denial in the light of presented evidence raises questions about the other's motives. Edward Skidelsky, a lecturer in philosophy at Exeter University
writes that "An accusation of 'denial' is serious, suggesting either
deliberate dishonesty or self-deception. The thing being denied is, by
implication, so obviously true that the denier must be driven by
perversity, malice or wilful blindness." He suggests that, by the
introduction of the word denier into further areas of historical and scientific debate, "One of the great achievements of The Enlightenment – the liberation of historical and scientific enquiry from dogma – is quietly being reversed".
Some people have suggested that because denial of the Holocaust is well known, advocates who use the term denialist
in other areas of debate may intentionally or unintentionally imply
that their opponents are little better than Holocaust deniers. However, Robert Galloet al. defended this latter comparison, stating that AIDS denialism is similar to Holocaust denial since it is a form of pseudoscience that "contradicts an immense body of research".
Many issues that are settled in the scientific community, such as
human responsibility for climate change, remain the subject of
politically or economically motivated attempts to downplay, dismiss or
deny them—an ideological phenomenon academics and scientists call climate change denial. Climate scientists, especially in the United States, have reported government and oil-industry pressure to censor or suppress their work and hide scientific data, with directives not to discuss the subject publicly. The fossil fuels lobby
has been identified as overtly or covertly supporting efforts to
undermine or discredit the scientific consensus on climate change.
AIDS denialism is the denial that the human immunodeficiency virus (HIV) is the cause of acquired immune deficiency syndrome (AIDS). AIDS denialism has been described as being "among the most vocal anti-science denial movements". Some denialists reject the existence of HIV, while others accept that the virus exists but say that it is a harmless passenger virus and not the cause of AIDS. Insofar as denialists acknowledge AIDS as a real disease, they attribute it to some combination of recreational drug use, malnutrition, poor sanitation, and side effects of antiretroviral medication, rather than infection with HIV. However, the evidence that HIV causes AIDS is scientifically conclusive and the scientific community rejects and ignores AIDS-denialist claims as based on faulty reasoning, cherry picking, and misrepresentation of mainly outdated scientific data. With the rejection of these arguments by the scientific community,
AIDS-denialist material is now spread mainly through the Internet.
Thabo Mbeki, former president of South Africa,
embraced AIDS denialism, proclaiming that AIDS was primarily caused by
poverty. About 365,000 people died from AIDS during his presidency; it
is estimated that around 343,000 premature deaths could have been
prevented if proper treatment had been available.
After
the December 2020 introduction of COVID vaccines, a partisan gap in
death rates developed, indicating the effects of vaccine skepticism. As of March 2024, more than 30 percent of Republicans had not received a
Covid vaccine, compared with less than 10 percent of Democrats.
"COVID is a lie" graffiti in Pontefract, West Yorkshire, England
The term "COVID-19 denialism" or merely "COVID denialism" refers to
the thinking of those who deny the reality of the COVID-19 pandemic, at least to the extent of denying the scientifically recognized COVID mortality data of the World Health Organization. The claims that the COVID-19 pandemic has been faked, exaggerated, or mischaracterized are pseudoscience. Some famous people who have engaged in COVID-19 denialism include Elon Musk, U.S. President Donald Trump, and former Brazilian President Bolsonaro.
The superseded belief that the Earth is flat, and denial of all of the overwhelming evidence that supports an approximately spherical Earth that rotates around its axis and orbits the Sun, persists into the 21st century. Modern proponents of flat-Earth cosmology (or flat-Earthers) refuse to accept any kind of contrary evidence, dismissing all spaceflights and images from space as hoaxes and accusing all organizations and even private citizens of conspiring to "hide the truth". They also claim that no actual satellites are orbiting the Earth, that the International Space Station is fake, and that these are lies from all governments involved in this grand cover-up. Some even believe other planets and stars are hoaxes.
Adherents of the modern flat-earth model propose that a dome-shaped firmament encloses a disk-shaped Earth. They may also claim, after Samuel Rowbotham, that the Sun is only 3,000 miles (4,800 km) above the Earth and that the Moon and the Sun orbit above the Earth rather than around it. Modern flat-earthers believe that Antarctica is not a continent but a massive ice floe,
with a wall 150 feet (46 m) or higher, which circles the perimeter of
the Earth and keeps everything (including all the oceans' water) from
falling off the edge.
Flat-Earthers also assert that no one is allowed to fly over or explore Antarctica,
despite contrary evidence. According to them, all photos and videos of
ships sinking under the horizon and of the bottoms of city skylines and clouds below the horizon, revealing the curvature of the Earth, have been manipulated, computer-generated, or somehow faked. Therefore, regardless of any scientific or empirical evidence provided, flat-Earthers conclude that it is fabricated or altered in some way.
When linked to other observed phenomena such as gravity, sunsets,
tides, eclipses, distances and other measurements that challenge the
flat earth model, claimants replace commonly accepted explanations with
piecemeal models that distort or over-simplify how perspective, mass,
buoyancy, light or other physical systems work. These piecemeal replacements rarely conform with each other, finally
leaving many flat-Earth claimants to agree that such phenomena remain
"mysteries" and more investigation is to be done. In this conclusion,
adherents remain open to all explanations except the commonly accepted
globular Earth model, shifting the debate from ignorance to denialism.
There is a scientific consensus that currently available food derived from genetically modified crops (GM) poses no greater risk to human health than conventional food, but that each GM food needs to be tested on a case-by-case basis before introduction. Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe. The legal and regulatory status of GM foods varies by country, with
some nations banning or restricting them, and others permitting them
with widely differing degrees of regulation.
Psychological analyses indicate that over 70% of GM food
opponents in the US are "absolute" in their opposition, experience
disgust at the thought of eating GM foods, and are "evidence
insensitive".
Statins
Statin denialism is a rejection of the medical worth of statins, a class of cholesterol-lowering drugs. Cardiologist Steven Nissen at Cleveland Clinic has commented "We are losing the battle for the hearts and minds of our patients to Web sites..." promoting unproven medical therapies. Harriet Hall sees a spectrum of statin denialism ranging from pseudoscientific
claims to the understatement of benefits and overstatement of side
effects, all of which is contrary to the scientific evidence.
Mental illness denial or mental disorder denial is where a person denies the existence of mental disorders. Serious analysts, as well as pseudoscientific movements, question the existence of certain disorders. A minority of professional researchers see disorders such as depression from a sociocultural perspective and argue that the solution to it is fixing a dysfunction in society, not in the person's brain. Some people may also deny that they have a mental illness after being
diagnosed, and certain analysts argue this denialism is usually fueled
by narcissistic injury. Anti-psychiatry movements such as Scientology promote mental illness denial by having alternative practices to psychiatry.
Election denial is baseless rejection of the outcome of a fair election. Since the 2020 United States presidential election, there has been an ongoing narrative asserting that it was fraudulent. Similar events have occurred in different countries: Brazil in 2022 when former president Jair Bolsonaro after his defeat in the 2022 Brazilian general election, questioning the accuracy of the country's electronic voting system. In the 2021 Peruvian general election,
presidential candidate Keiko Fujimori alleged fraud and irregularities
in the voting count which were disproved by election authorities and
international observers.
Historical negationism, the denialism of widely accepted historical
facts, is a major source of concern among historians and it is
frequently used to falsify or distort accepted historical events. In attempting to revise the
past, negationists are distinguished by the use of techniques
inadmissible in proper historical discourse, such as presenting known
forged documents as genuine, inventing ingenious but implausible reasons
for distrusting genuine documents, attributing conclusions to books and
sources that report the opposite, manipulating statistical series to
support the given point of view, and deliberately mistranslating texts.
Some countries, such as Germany, have criminalized the
negationist revision of certain historical events, while other countries
take a more cautious position for various reasons, such as the
protection of free speech.
Others mandate negationist views, such as California, where
schoolchildren have been explicitly prevented from learning about the California genocide.
Borrowing arguments used by the CUP to justify its actions,
Armenian genocide denial rests on the notion that the deportation of
Armenians was a legitimate state action in response to an alleged
Armenian uprising that threatened the empire's existence during wartime.
Deniers assert that the CUP intended to resettle Armenians, not kill
them. They claim the death toll is exaggerated or attribute the deaths
to other factors, such as a purported civil war, disease, bad weather, rogue local officials, or bands of Kurds and outlaws. The historian Ronald Grigor Suny summarizes the main argument as: "There was no genocide, and the Armenians were to blame for it."
A critical reason for denial is that the genocide enabled the establishment of a Turkish nation-state; recognizing it would contradict Turkey's founding myths. Since the 1920s, Turkey has worked to prevent recognition or even
mention of the genocide in other countries. It has spent millions of
dollars on lobbying, created research institutes, and used intimidation
and threats. Denial, according to Donald Bloxham, is usually accompanied by "rhetoric of Armenian treachery, aggression, criminality, and territorial ambition". Denial affects Turkey's domestic policies and is taught in Turkish
schools; some Turkish citizens who recognize the genocide have faced
prosecution for "insulting Turkishness". Turkey's century-long effort to deny the genocide sets it apart from other historical cases of genocide.
Azerbaijan, a close ally of Turkey,
also denies the genocide and campaigns against its recognition
internationally. Most Turkish citizens and political parties support
Turkey's denial policy. Scholars argue that Armenian genocide denial has
set the tone for the government's attitude towards minorities, and has
contributed to the ongoing violence against Kurds
in Turkey. A 2014 poll of 1,500 people conducted by EDAM, a Turkish
think tank, found that nine percent of Turkish citizens recognize the
genocide.
Nakba denial refers to attempts to downgrade, deny and misdescribe the ethnic cleansing of Palestinians during the Nakba, in which four-fifths of all Palestinians were driven off their lands and into exile.
Sonja Biserko, president of the Helsinki Committee for Human Rights in Serbia,
and Edina Bečirević, the Faculty of Criminalistics, Criminology and
Security Studies of the University of Sarajevo have pointed to a culture
of denial of the Srebrenica massacre
in Serbian society, taking many forms and present in particular in
political discourse, the media, the law and the educational system.
Confirmation bias (also confirmatory bias, myside bias, or congeniality bias) is the tendency to search for, interpret, favor and recall information in a way that confirms or supports one's prior beliefs or values or decisions. People display this bias when they select information
that supports their views, ignoring contrary information or when they
interpret ambiguous evidence as supporting their existing attitudes. The
effect is strongest for desired outcomes, emotionally charged issues and deeply entrenched beliefs.
Biased search for information, biased interpretation of this
information and biased memory recall have been invoked to explain four
specific effects:
attitude polarization (when a disagreement becomes more extreme despite the different parties being exposed to the same evidence)
belief perseverance (when beliefs persist after the evidence for them is shown to be false)
the irrational primacy effect (a greater reliance on information encountered early in a series)
illusory correlation (when people falsely perceive an association between two events or situations).
A series of psychological experiments
in the 1960s suggested that people are biased toward confirming their
existing beliefs. Later work reinterpreted these results as a tendency
to test ideas in a one-sided way, focusing on one possibility and
ignoring alternatives. Explanations for the observed biases include wishful thinking
and the limited human capacity to process information. Another proposal
is that people show confirmation bias because they are pragmatically
assessing the costs of being wrong rather than investigating in a
neutral, scientific way.
Flawed decisions
due to confirmation bias have been found in a wide range of political,
organizational, financial and scientific contexts. These biases
contribute to overconfidence
in personal beliefs and can maintain or strengthen beliefs in the face
of contrary evidence. For example, confirmation bias produces systematic
errors in scientific research based on inductive reasoning
(the gradual accumulation of supportive evidence). Similarly, a police
detective may identify a suspect early in an investigation, but then may
only seek confirming rather than disconfirming evidence. A medical
practitioner may prematurely focus on a particular disorder early in a
diagnostic session, and then seek only confirming evidence. In social media, confirmation bias is amplified by the use of filter bubbles
and "algorithmic editing", which display to individuals only
information they are likely to agree with, while excluding opposing
views.
Definition and context
Confirmation bias, previously used as a "catch-all phrase", was refined by English psychologist Peter Wason, as "a preference for information that is consistent with a hypothesis rather than information which opposes it."
Some psychologists restrict the term "confirmation bias" to
selective collection of evidence that supports what one already believes
while ignoring or rejecting evidence that supports a different
conclusion. Others apply the term more broadly to the tendency to
preserve one's existing beliefs when searching for evidence,
interpreting it, or recalling it from memory. Confirmation bias is a result of automatic, unintentional strategies rather than deliberate deception.
Types
Biased search for information
Confirmation bias has been described as an internal "yes man", echoing back a person's beliefs like Charles Dickens's character Uriah Heep.
Experiments have found repeatedly that people tend to test hypotheses
in a one-sided way, by searching for evidence consistent with their
current hypothesis. Rather than searching through all the relevant evidence, they phrase
questions to receive an affirmative answer that supports their theory. They look for the consequences that they would expect if their
hypothesis were true, rather than what would happen if it were false. For example, someone using yes/no questions to find a number they suspect to be the number 3 might ask, "Is it an odd number?"
People prefer this type of question, called a "positive test", even
when a negative test such as "Is it an even number?" would yield exactly
the same information. However, this does not mean that people seek tests that guarantee a
positive answer. In studies where subjects could select either such
pseudo-tests or genuinely diagnostic ones, they favored the genuinely
diagnostic.
The preference for positive tests in itself is not a bias, since positive tests can be highly informative. However, in combination with other effects, this strategy can confirm
existing beliefs or assumptions, independently of whether they are true. In real-world situations, evidence is often complex and mixed. For
example, various contradictory ideas about someone could each be
supported by concentrating on one aspect of his or her behavior. Thus any search for evidence in favor of a hypothesis is likely to succeed. One illustration of this is the way the phrasing of a question can significantly change the answer. For example, people who are asked, "Are you happy with your social
life?" report greater satisfaction than those asked, "Are you unhappy with your social life?"
Even a small change in a question's wording can affect how people
search through available information, and hence the conclusions they
reach. This was shown using a fictional child custody case. Participants read that Parent A was moderately suitable to be the
guardian in multiple ways. Parent B had a mix of salient positive and
negative qualities: a close relationship with the child but a job that
would take them away for long periods of time. When asked, "Which parent
should have custody of the child?" the majority of participants chose
Parent B, looking mainly for positive attributes. However, when asked,
"Which parent should be denied custody of the child?" they looked for
negative attributes and the majority answered that Parent B should be
denied custody, implying that Parent A should have custody.
Similar studies have demonstrated how people engage in a biased
search for information, but also that this phenomenon may be limited by a
preference for genuine diagnostic tests. In an initial experiment,
participants rated another person on the introversion–extroversion
personality dimension on the basis of an interview. They chose the
interview questions from a given list. When the interviewee was
introduced as an introvert, the participants chose questions that
presumed introversion, such as, "What do you find unpleasant about noisy
parties?" When the interviewee was described as extroverted, almost all
the questions presumed extroversion, such as, "What would you do to
liven up a dull party?" These loaded questions gave the interviewees little or no opportunity to falsify the hypothesis about them. A later version of the experiment gave the participants less
presumptive questions to choose from, such as, "Do you shy away from
social interactions?" Participants preferred to ask these more diagnostic questions, showing
only a weak bias towards positive tests. This pattern, of a main
preference for diagnostic tests and a weaker preference for positive
tests, has been replicated in other studies.
Personality traits influence and interact with biased search processes. Individuals vary in their abilities to defend their attitudes from external attacks in relation to selective exposure.
Selective exposure occurs when individuals search for information that
is consistent, rather than inconsistent, with their personal beliefs. An experiment examined the extent to which individuals could refute arguments that contradicted their personal beliefs. People with high confidence
levels more readily seek out contradictory information to their
personal position to form an argument. This can take the form of an oppositional news consumption, where individuals seek opposing partisan news in order to counterargue. Individuals with low confidence levels do not seek out contradictory
information and prefer information that supports their personal
position. People generate and evaluate evidence in arguments that are
biased towards their own beliefs and opinions. Heightened confidence levels decrease preference for information that supports individuals' personal beliefs.
Another experiment gave participants a complex rule-discovery task that involved moving objects simulated by a computer. Objects on the computer screen followed specific laws, which the
participants had to figure out. So, participants could "fire" objects
across the screen to test their hypotheses. Despite making many attempts
over a ten-hour session, none of the participants figured out the rules
of the system. They typically attempted to confirm rather than falsify
their hypotheses, and were reluctant to consider alternatives. Even
after seeing objective evidence that refuted their working hypotheses,
they frequently continued doing the same tests. Some of the participants
were taught proper hypothesis-testing, but these instructions had
almost no effect.
Biased interpretation of information
Smart people believe weird things because they are skilled at defending beliefs they arrived at for non-smart reasons.
Confirmation biases are not limited to the collection of evidence.
Even if two individuals have the same information, the way they
interpret it can be biased.
A team at Stanford University
conducted an experiment involving participants who felt strongly about
capital punishment, with half in favor and half against it. Each participant read descriptions of two studies: a comparison of U.S. states
with and without the death penalty, and a comparison of murder rates in
a state before and after the introduction of the death penalty. After
reading a quick description of each study, the participants were asked
whether their opinions had changed. Then, they read a more detailed
account of each study's procedure and had to rate whether the research
was well-conducted and convincing. In fact, the studies were fictional. Half the participants were told that one kind of study supported the deterrent effect and the other undermined it, while for other participants the conclusions were swapped.
The participants, whether supporters or opponents, reported
shifting their attitudes slightly in the direction of the first study
they read. Once they read the more detailed descriptions of the two
studies, they almost all returned to their original belief regardless of
the evidence provided, pointing to details that supported their
viewpoint and disregarding anything contrary. Participants described
studies supporting their pre-existing view as superior to those that
contradicted it, in detailed and specific ways. Writing about a study that seemed to undermine the deterrence effect, a
death penalty proponent wrote, "The research didn't cover a long enough
period of time," while an opponent's comment on the same study said,
"No strong evidence to contradict the researchers has been presented." The results illustrated that people set higher standards of evidence
for hypotheses that go against their current expectations. This effect,
known as "disconfirmation bias", has been supported by other
experiments.
Another study of biased interpretation occurred during the 2004 U.S. presidential election
and involved participants who reported having strong feelings about the
candidates. They were shown apparently contradictory pairs of
statements, either from Republican candidate George W. Bush, Democratic candidate John Kerry
or a politically neutral public figure. They were also given further
statements that made the apparent contradiction seem reasonable. From
these three pieces of information, they had to decide whether each
individual's statements were inconsistent.
There were strong differences in these evaluations, with participants
much more likely to interpret statements from the candidate they opposed
as contradictory.
An MRI scanner allowed researchers to examine how the human brain deals with dissonant information.
In this experiment, the participants made their judgments while in a magnetic resonance imaging
(MRI) scanner which monitored their brain activity. As participants
evaluated contradictory statements by their favored candidate, emotional
centers of their brains were aroused. This did not happen with the
statements by the other figures. The experimenters inferred that the
different responses to the statements were not due to passive reasoning
errors. Instead, the participants were actively reducing the cognitive dissonance induced by reading about their favored candidate's irrational or hypocritical behavior.
Biases in belief interpretation are persistent, regardless of intelligence level. Participants in an experiment took the SAT
test (a college admissions test used in the United States) to assess
their intelligence levels. They then read information regarding safety
concerns for vehicles, and the experimenters manipulated the national
origin of the car. American participants provided their opinion if the
car should be banned on a six-point scale, where one indicated
"definitely yes" and six indicated "definitely no". Participants firstly
evaluated if they would allow a dangerous German car on American
streets and a dangerous American car on German streets. Participants
believed that the dangerous German car on American streets should be
banned more quickly than the dangerous American car on German streets.
There was no difference among intelligence levels at the rate
participants would ban a car.
Biased interpretation is not restricted to emotionally
significant topics. In another experiment, participants were told a
story about a theft. They had to rate the evidential importance of
statements arguing either for or against a particular character being
responsible. When they hypothesized that character's guilt, they rated
statements supporting that hypothesis as more important than conflicting
statements.
Biased recall of information
People may remember evidence selectively to reinforce their
expectations, even if they gather and interpret evidence in a neutral
manner. This effect is called "selective recall", "confirmatory memory",
or "access-biased memory". Psychological theories differ in their predictions about selective recall. Schema theory
predicts that information matching prior expectations will be more
easily stored and recalled than information that does not match. Some alternative approaches say that surprising information stands out and so is memorable. Predictions from both these theories have been confirmed in different experimental contexts, with no theory winning outright.
In one study, participants read a profile of a woman which described a mix of introverted and extroverted behaviors. They later had to recall examples of her introversion and extroversion.
One group was told this was to assess the woman for a job as a
librarian, while a second group were told it was for a job in real
estate sales. There was a significant difference between what these two
groups recalled, with the "librarian" group recalling more examples of
introversion and the "sales" groups recalling more extroverted behavior. A selective memory effect has also been shown in experiments that manipulate the desirability of personality types. In one of these, a group of participants were shown evidence that
extroverted people are more successful than introverts. Another group
were told the opposite. In a subsequent, apparently unrelated study,
participants were asked to recall events from their lives in which they
had been either introverted or extroverted. Each group of participants
provided more memories connecting themselves with the more desirable
personality type, and recalled those memories more quickly.
Changes in emotional states can also influence memory recall. Participants rated how they felt when they had first learned that O. J. Simpson had been acquitted of murder charges. They described their emotional reactions and confidence regarding the
verdict one week, two months, and one year after the trial. Results
indicated that participants' assessments for Simpson's guilt changed
over time. The more that participants' opinion of the verdict had
changed, the less stable were the participant's memories regarding their
initial emotional reactions. When participants recalled their initial
emotional reactions two months and a year later, past appraisals closely
resembled current appraisals of emotion. People demonstrate sizable
myside bias when discussing their opinions on controversial topics. Memory recall and construction of experiences undergo revision in relation to corresponding emotional states.
Myside bias has been shown to influence the accuracy of memory recall. In an experiment, widows and widowers rated the intensity of their
experienced grief six months and five years after the deaths of their
spouses. Participants noted a higher experience of grief at six months
rather than at five years. Yet, when the participants were asked after
five years how they had felt six months after the death of their
significant other, the intensity of grief participants recalled was
highly correlated
with their current level of grief. Individuals appear to utilize their
current emotional states to analyze how they must have felt when
experiencing past events. Emotional memories are reconstructed by current emotional states.
One study showed how selective memory can maintain belief in extrasensory perception (ESP). Believers and disbelievers were each shown descriptions of ESP
experiments. Half of each group were told that the experimental results
supported the existence of ESP, while the others were told they did not.
In a subsequent test, participants recalled the material accurately,
apart from believers who had read the non-supportive evidence. This
group remembered significantly less information and some of them
incorrectly remembered the results as supporting ESP.
Individual differences
Myside bias was once believed to be correlated with intelligence;
however, studies have shown that myside bias can be more influenced by
ability to rationally think as opposed to level of intelligence. Myside bias can cause an inability to effectively and logically
evaluate the opposite side of an argument. Studies have stated that
myside bias is an absence of "active open-mindedness", meaning the
active search for why an initial idea may be wrong. Typically, myside bias is operationalized in empirical studies as the
quantity of evidence used in support of their side in comparison to the
opposite side.
A study has found individual differences in myside bias. This
study investigates individual differences that are acquired through
learning in a cultural context and are mutable. The researcher found
important individual difference in argumentation. Studies have suggested
that individual differences such as deductive reasoning ability,
ability to overcome belief bias, epistemological understanding, and
thinking disposition are significant predictors of the reasoning and
generating arguments, counterarguments, and rebuttals.
A study by Christopher Wolfe and Anne Britt also investigated how
participants' views of "what makes a good argument?" can be a source of
myside bias that influences the way a person formulates their own
arguments. The study investigated individual differences of argumentation schema
and asked participants to write essays. The participants were randomly
assigned to write essays either for or against their preferred side of
an argument and were given research instructions that took either a
balanced or an unrestricted approach. The balanced-research instructions
directed participants to create a "balanced" argument, i.e., that
included both pros and cons; the unrestricted-research instructions
included nothing on how to create the argument.
Overall, the results revealed that the balanced-research
instructions significantly increased the incidence of opposing
information in arguments. These data also reveal that personal belief is
not a source of myside bias; however, that those participants,
who believe that a good argument is one that is based on facts, are more
likely to exhibit myside bias than other participants. This evidence is
consistent with the claims proposed in Baron's article—that people's
opinions about what makes good thinking can influence how arguments are
generated.
Before psychological research on confirmation bias, the phenomenon
had been observed throughout history. Beginning with the Greek historian
Thucydides (c. 460 BC – c. 395 BC), who wrote of misguided reason in The Peloponnesian War;
"... for it is a habit of mankind to entrust to careless hope what they
long for, and to use sovereign reason to thrust aside what they do not
fancy". Italian poet Dante Alighieri (1265–1321) noted it in the Divine Comedy, in which St. Thomas Aquinas
cautions Dante upon meeting in Paradise, "opinion—hasty—often can
incline to the wrong side, and then affection for one's own opinion
binds, confines the mind". Ibn Khaldun noticed the same effect in his Muqaddimah:
Untruth naturally afflicts
historical information. There are various reasons that make this
unavoidable. One of them is partisanship for opinions and schools. ...
if the soul is infected with partisanship for a particular opinion or
sect, it accepts without a moment's hesitation the information that is
agreeable to it. Prejudice and partisanship obscure the critical faculty
and preclude critical investigation. The result is that falsehoods are
accepted and transmitted.
In the Novum Organum, English philosopher and scientist Francis Bacon (1561–1626) noted that biased assessment of evidence drove "all superstitions,
whether in astrology, dreams, omens, divine judgments or the like". He wrote:
The human understanding when it
has once adopted an opinion ... draws all things else to support and
agree with it. And though there be a greater number and weight of
instances to be found on the other side, yet these it either neglects or
despises, or else by some distinction sets aside or rejects[.]
In the second volume of his The World as Will and Representation (1844), German philosopher Arthur Schopenhauer
observed that "An adopted hypothesis gives us lynx-eyes for everything
that confirms it and makes us blind to everything that contradicts it."
I know that most men—not only those
considered clever, but even those who are very clever, and capable of
understanding most difficult scientific, mathematical, or philosophic
problems—can very seldom discern even the simplest and most obvious
truth if it be such as to oblige them to admit the falsity of
conclusions they have formed, perhaps with much difficulty—conclusions
of which they are proud, which they have taught to others, and on which
they have built their lives.
The most difficult subjects can
be explained to the most slow-witted man if he has not formed any idea
of them already; but the simplest thing cannot be made clear to the most
intelligent man if he is firmly persuaded that he knows already,
without a shadow of doubt, what is laid before him.
In Peter Wason's initial experiment published in 1960 (which does not
mention the term "confirmation bias"), he repeatedly challenged
participants to identify a rule applying to triples of numbers. They
were told that (2,4,6) fits the rule. They generated triples, and the
experimenter told them whether each triple conformed to the rule.
The actual rule was simply "any ascending sequence", but
participants had great difficulty in finding it, often announcing rules
that were far more specific, such as "the middle number is the average
of the first and last". The participants seemed to test only positive examples—triples that
obeyed their hypothesized rule. For example, if they thought the rule
was, "Each number is two greater than its predecessor," they would offer
a triple that fitted (confirmed) this rule, such as (11,13,15) rather
than a triple that violated (falsified) it, such as (11,12,19).
Wason interpreted his results as showing a preference for
confirmation over falsification, hence he coined the term "confirmation
bias". Wason also used confirmation bias to explain the results of his selection task experiment. Participants repeatedly performed badly on various forms of this test,
in most cases ignoring information that could potentially refute
(falsify) the specified rule.
Hypothesis testing (positive test strategy) explanation (Klayman and Ha)
Klayman and Ha's 1987 paper argues that the Wason experiments do not
actually demonstrate a bias towards confirmation, but instead a tendency
to make tests consistent with the working hypothesis. They called this the "positive test strategy". This strategy is an example of a heuristic: a reasoning shortcut that is imperfect but easy to compute. Klayman and Ha used Bayesian probability and information theory
as their standard of hypothesis-testing, rather than the
falsificationism used by Wason. According to these ideas, each answer to
a question yields a different amount of information, which depends on
the person's prior beliefs. Thus a scientific test of a hypothesis is
one that is expected to produce the most information. Since the
information content depends on initial probabilities, a positive test
can either be highly informative or uninformative. Klayman and Ha argued
that when people think about realistic problems, they are looking for a
specific answer with a small initial probability. In this case,
positive tests are usually more informative than negative tests. However, in Wason's rule discovery task the answer—three numbers in
ascending order—is very broad, so positive tests are unlikely to yield
informative answers. Klayman and Ha supported their analysis by citing
an experiment that used the labels "DAX" and "MED" in place of "fits the
rule" and "doesn't fit the rule". This avoided implying that the aim
was to find a low-probability rule. Participants had much more success
with this version of the experiment.
If
the true rule (T) encompasses the current hypothesis (H), then positive
tests (examining an H to see if it is T) will not show that the
hypothesis is false.
If the true rule (T) overlaps the current hypothesis (H), then either a negative test or a positive test can potentially falsify H.
When the working hypothesis (H) includes the true rule (T) then positive tests are the only way to falsify H.
In light of this and other critiques, the focus of research moved
away from confirmation versus falsification of an hypothesis, to
examining whether people test hypotheses in an informative way, or an
uninformative but positive way. The search for "true" confirmation bias
led psychologists to look at a wider range of effects in how people
process information.
Information processing explanations
There are currently three main information processing explanations of confirmation bias, plus a recent addition.
Cognitive versus motivational
Happy events are more likely to be remembered.
According to Robert MacCoun, most biased evidence processing occurs through a combination of "cold" (cognitive) and "hot" (motivated) mechanisms.
Cognitive explanations for confirmation bias are based on
limitations in people's ability to handle complex tasks, and the
shortcuts, called heuristics, that they use. For example, people may judge the reliability of evidence by using the availability heuristic that is, how readily a particular idea comes to mind. It is also possible that people can only focus on one thought at a
time, so find it difficult to test alternative hypotheses in parallel.
Another heuristic is the positive test strategy identified by Klayman
and Ha, in which people test a hypothesis by examining cases where they
expect a property or event to occur. This heuristic avoids the difficult
or impossible task of working out how diagnostic each possible question
will be. However, it is not universally reliable, so people can
overlook challenges to their existing beliefs.
Motivational explanations involve an effect of desire on belief. It is known that people prefer positive thoughts over negative ones in a number of ways: this is called the "Pollyanna principle". Applied to arguments or sources of evidence,
this could explain why desired conclusions are more likely to be
believed true. According to experiments that manipulate the desirability
of the conclusion, people demand a high standard of evidence for
unpalatable ideas and a low standard for preferred ideas. In other
words, they ask, "Can I believe this?" for some suggestions and, "Must I
believe this?" for others. Although consistency
is a desirable feature of attitudes, an excessive drive for consistency
is another potential source of bias because it may prevent people from
neutrally evaluating new, surprising information. Social psychologist Ziva Kunda
combines the cognitive and motivational theories, arguing that
motivation creates the bias, but cognitive factors determine the size of
the effect.
Cost-benefit
Explanations in terms of cost-benefit analysis assume that people do not just test hypotheses in a disinterested way, but assess the costs of different errors. Using ideas from evolutionary psychology, James Friedrich suggests that people do not primarily aim at truth
in testing hypotheses, but try to avoid the most costly errors. For
example, employers might ask one-sided questions in job interviews
because they are focused on weeding out unsuitable candidates. Yaacov Trope
and Akiva Liberman's refinement of this theory assumes that people
compare the two different kinds of error: accepting a false hypothesis
or rejecting a true hypothesis. For instance, someone who underestimates
a friend's honesty might treat him or her suspiciously and so undermine
the friendship. Overestimating the friend's honesty may also be costly,
but less so. In this case, it would be rational to seek, evaluate or
remember evidence of their honesty in a biased way. When someone gives an initial impression of being introverted or
extroverted, questions that match that impression come across as more empathic. This suggests that when talking to someone who seems to be an introvert, it is a sign of better social skills
to ask, "Do you feel awkward in social situations?" rather than, "Do
you like noisy parties?" The connection between confirmation bias and
social skills was corroborated by a study of how college students get to
know other people. Highly self-monitoring students, who are more sensitive to their environment and to social norms, asked more matching questions when interviewing a high-status staff member than when getting to know fellow students.
Exploratory versus confirmatory
Psychologists Jennifer Lerner and Philip Tetlock distinguish two different kinds of thinking process. Exploratory thought neutrally considers multiple points of view and tries to anticipate all possible objections to a particular position, while confirmatory thought
seeks to justify a specific point of view. Lerner and Tetlock say that
when people expect to justify their position to others whose views they
already know, they will tend to adopt a similar position to those
people, and then use confirmatory thought to bolster their own
credibility. However, if the external parties are overly aggressive or
critical, people will disengage from thought altogether, and simply
assert their personal opinions without justification. Lerner and Tetlock
say that people only push themselves to think critically and logically
when they know in advance they will need to explain themselves to others
who are well-informed, genuinely interested in the truth, and whose
views they do not already know. Because those conditions rarely exist,
they argue, most people are using confirmatory thought most of the time.
Make-believe
Developmental psychologist Eve Whitmore has argued that beliefs and
biases involved in confirmation bias have their roots in childhood
coping through make-believe, which becomes "the basis for more complex
forms of self-deception and illusion into adulthood." The friction
brought on by questioning as an adolescent with developing critical
thinking can lead to the rationalization of false beliefs, and the habit
of such rationalization can become unconscious over the years.
Optimal information acquisition
Recent research in economics has challenged the traditional view of confirmation bias as purely a cognitive flaw. Under conditions where acquiring and processing information is costly,
seeking confirmatory evidence can actually be an optimal strategy.
Instead of pursuing contrarian or disconfirming evidence, it may be more
efficient to focus on sources likely to align with one's existing
beliefs, given the constraints on time and resources.
Economist Weijie Zhong has developed a model demonstrating that
individuals who must make decisions under time pressure, and who face
costs for obtaining more information, will often prefer confirmatory
signals. According to this model, when individuals believe strongly in a
certain hypothesis, they optimally seek information that confirms it,
allowing them to build confidence more efficiently. If the expected
confirmatory signals are not received, their confidence in the initial
hypothesis will gradually decline, leading to belief updating. This
approach shows that seeking confirmation is not necessarily biased but
may be a rational allocation of limited attention and resources.
Real-world effects
Social media
In social media, confirmation bias is amplified by the use of filter bubbles and echo chambers
(or "algorithmic editing"), which displays to individuals only
information they are likely to agree with, while excluding opposing
views. Some have argued that confirmation bias is the reason why society can
never escape from filter bubbles, because individuals are
psychologically hardwired to seek information that agrees with their
preexisting values and beliefs. Others have further argued that the mixture of the two is degrading democracy—claiming
that this "algorithmic editing" removes diverse viewpoints and
information—and that unless filter bubble algorithms are removed, voters
will be unable to make fully informed political decisions.
The rise of social media has contributed greatly to the rapid spread of fake news,
that is, false and misleading information that is presented as credible
news from a seemingly reliable source. Confirmation bias (selecting or
reinterpreting evidence to support one's beliefs) is one of three main
hurdles cited as to why critical thinking goes astray in these
circumstances. The other two are shortcut heuristics (when overwhelmed
or short of time, people rely on simple rules such as group consensus or
trusting an expert or role model) and social goals (social motivation
or peer pressure can interfere with objective analysis of facts at
hand).
In combating the spread of fake news, social media sites have considered turning toward "digital nudging". This can currently be done in two different forms of nudging. This
includes nudging of information and nudging of presentation. Nudging of
information entails social media sites providing a disclaimer or label
questioning or warning users of the validity of the source while nudging
of presentation includes exposing users to new information which they
may not have sought out but could introduce them to viewpoints that may
combat their own confirmation biases.
Many times in the history of science, scientists have resisted new discoveries by selectively interpreting or ignoring unfavorable data.
Several studies have shown that scientists rate studies that report
findings consistent with their prior beliefs more favorably than studies
reporting findings inconsistent with their previous beliefs.
However, assuming that the research question is relevant, the
experimental design adequate and the data are clearly and
comprehensively described, the empirical data obtained should be
important to the scientific community and should not be viewed
prejudicially, regardless of whether they conform to current theoretical
predictions. In practice, researchers may misunderstand, misinterpret, or not read
at all studies that contradict their preconceptions, or wrongly cite
them anyway as if they actually supported their claims.
Further, confirmation biases can sustain scientific theories or
research programs in the face of inadequate or even contradictory
evidence. The discipline of parapsychology is often cited as an example.
An experimenter's confirmation bias can potentially affect which
data are reported. Data that conflict with the experimenter's
expectations may be more readily discarded as unreliable, producing the
so-called file drawer effect. To combat this tendency, scientific training teaches ways to prevent bias. For example, experimental design of randomized controlled trials (coupled with their systematic review) aims to minimize sources of bias.
The social process of peer review
aims to mitigate the effect of individual scientists' biases, even
though the peer review process itself may be susceptible to such biases. Confirmation bias may thus be especially harmful to objective
evaluations regarding nonconforming results since biased individuals may
regard opposing evidence to be weak in principle and give little
serious thought to revising their beliefs. Scientific innovators often meet with resistance from the scientific
community, and research presenting controversial results frequently
receives harsh peer review.
Confirmation bias can lead investors to be overconfident, ignoring evidence that their strategies will lose money. In studies of political stock markets,
investors made more profit when they resisted bias. For example,
participants who interpreted a candidate's debate performance in a
neutral rather than partisan way were more likely to profit. To combat the effect of confirmation bias, investors can try to adopt a contrary viewpoint "for the sake of argument". In one technique, they imagine that their investments have collapsed and ask themselves why this might happen.
Medicine and health
Cognitive biases are important variables in clinical decision-making
by medical general practitioners (GPs) and medical specialists. Two
important ones are confirmation bias and the overlapping availability
bias. A GP may make a diagnosis early on during an examination, and then
seek confirming evidence rather than falsifying evidence. This
cognitive error is partly caused by the availability of evidence about
the supposed disorder being diagnosed. For example, the client may have
mentioned the disorder, or the GP may have recently read a
much-discussed paper about the disorder. The basis of this cognitive
shortcut or heuristic (termed anchoring) is that the doctor does not
consider multiple possibilities based on evidence, but prematurely
latches on (or anchors to) a single cause. In emergency medicine, because of time pressure, there is a high
density of decision-making, and shortcuts are frequently applied. The
potential failure rate of these cognitive decisions needs to be managed
by education about the 30 or more cognitive biases that can occur, so as
to set in place proper debiasing strategies. Confirmation bias may also cause doctors to perform unnecessary medical procedures due to pressure from adamant patients.
Mental disorders may be prone to misdiagnosis in being based upon
observations and self-reporting rather than objective testing.
Confirmation bias may play a role when practitioners stick with an early
diagnosis.
Raymond Nickerson, a psychologist, blames confirmation bias for
the ineffective medical procedures that were used for centuries before
the arrival of scientific medicine.
If a patient recovered, medical authorities counted the treatment as
successful, rather than looking for alternative explanations such as
that the disease had run its natural course. Biased assimilation is a
factor in the modern appeal of alternative medicine, whose proponents are swayed by positive anecdotal evidence but treat scientific evidence hyper-critically.
Cognitive therapy was developed by Aaron T. Beck in the early 1960s and has become a popular approach. According to Beck, biased information processing is a factor in depression. His approach teaches people to treat evidence impartially, rather than selectively reinforcing negative outlooks. Phobias and hypochondria have also been shown to involve confirmation bias for threatening information.
Politics, law and policing
Mock trials allow researchers to examine confirmation biases in a realistic setting.
Nickerson argues that reasoning in judicial and political contexts is
sometimes subconsciously biased, favoring conclusions that judges,
juries or governments have already committed to.
Since the evidence in a jury trial can be complex, and jurors often
reach decisions about the verdict early on, it is reasonable to expect
an attitude polarization effect. The prediction that jurors will become
more extreme in their views as they see more evidence has been borne out
in experiments with mock trials. Both inquisitorial and adversarial criminal justice systems are affected by confirmation bias.
Confirmation bias can be a factor in creating or extending
conflicts, from emotionally charged debates to wars: by interpreting the
evidence in their favor, each opposing party can become overconfident
that it is in the stronger position. On the other hand, confirmation bias can result in people ignoring or
misinterpreting the signs of an imminent or incipient conflict. For
example, psychologists Stuart Sutherland and Thomas Kida have each argued that U.S. Navy Admiral Husband E. Kimmel showed confirmation bias when playing down the first signs of the Japanese attack on Pearl Harbor.
A two-decade study of political pundits by Philip E. Tetlock
found that, on the whole, their predictions were not much better than
chance. Tetlock divided experts into "foxes" who maintained multiple
hypotheses, and "hedgehogs" who were more dogmatic. In general, the
hedgehogs were much less accurate. Tetlock blamed their failure on
confirmation bias, and specifically on their inability to make use of
new information that contradicted their existing theories.
In police investigations, a detective may identify a suspect
early in an investigation, but then sometimes largely seek supporting or
confirming evidence, ignoring or downplaying falsifying evidence.
Self concept and self esteem
Social psychologists have identified two tendencies in the way people seek or interpret information about themselves. Self-verification is the drive to reinforce the existing self-image and self-enhancement is the drive to seek positive feedback. Both are served by confirmation biases. In experiments where people are given feedback that conflicts with
their self-image, they are less likely to attend to it or remember it
than when given self-verifying feedback. They reduce the impact of such information by interpreting it as unreliable. Similar experiments have found a preference for positive feedback, and the people who give it, over negative feedback.
Mass delusions
Confirmation bias can play a key role in the propagation of mass delusions. Witch trials are frequently cited as an example.
For another example, in the Seattle windshield pitting epidemic,
there seemed to be a "pitting epidemic" in which windshields were
damaged due to an unknown cause. As news of the apparent wave of damage
spread, more and more people checked their windshields, discovered that
their windshields too had been damaged, thus confirming belief in the
supposed epidemic. In fact, the windshields were previously damaged, but
the damage went unnoticed until people checked their windshields as the
delusion spread.
Paranormal beliefs
One factor in the appeal of alleged psychic readings is that listeners apply a confirmation bias which fits the psychic's statements to their own lives. By making a large number of ambiguous statements in each sitting, the
psychic gives the client more opportunities to find a match. This is one
of the techniques of cold reading, with which a psychic can deliver a subjectively impressive reading without any prior information about the client. Investigator James Randi
compared the transcript of a reading to the client's report of what the
psychic had said, and found that the client showed a strong selective
recall of the "hits".
As a striking illustration of confirmation bias in the real world, Nickerson mentions numerological pyramidology: the practice of finding meaning in the proportions of the Egyptian pyramids.There are many different length measurements that can be made of, for example, the Great Pyramid of Giza
and many ways to combine or manipulate them. Hence it is almost
inevitable that people who look at these numbers selectively will find
superficially impressive correspondences, for example with the
dimensions of the Earth.
Recruitment and selection
Unconscious cognitive bias (including confirmation bias) in job recruitment
can affect hiring decisions and can potentially prohibit a diverse and
inclusive workplace. There are a variety of unconscious biases that can
affect recruitment decisions, and confirmation bias is one of the major
ones, especially during the interview stage. The interviewer may select a candidate that confirms their own beliefs,
even though other candidates are equally or better qualified.
When people with opposing views interpret new information in a biased
way, their views can move even further apart. This is called "attitude
polarization". The effect was demonstrated by an experiment that involved drawing a
series of red and black balls from one of two concealed "bingo baskets".
Participants knew that one basket contained 60 percent black and 40
percent red balls; the other, 40 percent black and 60 percent red. The
experimenters looked at what happened when balls of alternating color
were drawn in turn, a sequence that does not favor either basket. After
each ball was drawn, participants in one group were asked to state out
loud their judgments of the probability that the balls were being drawn
from one or the other basket. These participants tended to grow more
confident with each successive draw—whether they initially thought the
basket with 60 percent black balls or the one with 60 percent red balls
was the more likely source, their estimate of the probability increased.
Another group of participants were asked to state probability estimates
only at the end of a sequence of drawn balls, rather than after each
ball. They did not show the polarization effect, suggesting that it does
not necessarily occur when people simply hold opposing positions, but
rather when they openly commit to them.
A less abstract study was the Stanford biased interpretation
experiment, in which participants with strong opinions about the death
penalty read about mixed experimental evidence. Twenty-three percent of
the participants reported that their views had become more extreme, and
this self-reported shift correlated strongly with their initial
attitudes. In later experiments, participants also reported their opinions
becoming more extreme in response to ambiguous information. However,
comparisons of their attitudes before and after the new evidence showed
no significant change, suggesting that the self-reported changes might
not be real. Based on these experiments, Deanna Kuhn and Joseph Lao concluded that
polarization is a real phenomenon but far from inevitable, only
happening in a small minority of cases, and it was prompted not only by
considering mixed evidence, but by merely thinking about the topic.
Charles Taber and Milton Lodge argued that the Stanford team's
result had been hard to replicate because the arguments used in later
experiments were too abstract or confusing to evoke an emotional
response. The Taber and Lodge study used the emotionally charged topics
of gun control and affirmative action. They measured the attitudes of their participants towards these issues
before and after reading arguments on each side of the debate. Two
groups of participants showed attitude polarization: those with strong
prior opinions and those who were politically knowledgeable. In part of
this study, participants chose which information sources to read, from a
list prepared by the experimenters. For example, they could read
arguments on gun control from the National Rifle Association of America and the Brady Anti-Handgun Coalition.
Even when instructed to be even-handed, participants were more likely
to read arguments that supported their existing attitudes than arguments
that did not. This biased search for information correlated well with
the polarization effect.
The backfire effect
is a name for the finding that given evidence against their beliefs,
people can reject the evidence and believe even more strongly. The phrase was coined by Brendan Nyhan and Jason Reifler in 2010. However, subsequent research has since failed to replicate findings supporting the backfire effect. One study conducted out of the Ohio State University and George
Washington University studied 10,100 participants with 52 different
issues expected to trigger a backfire effect. While the findings did
conclude that individuals are reluctant to embrace facts that contradict
their already held ideology, no cases of backfire were detected. The backfire effect has since been noted to be a rare phenomenon rather than a common occurrence (compare the boomerang effect).
Beliefs can survive potent logical or empirical challenges. They can
survive and even be bolstered by evidence that most uncommitted
observers would agree logically demands some weakening of such beliefs.
They can even survive the total destruction of their original evidential
bases.
—Lee Ross and Craig Anderson
Confirmation biases provide one plausible explanation for the
persistence of beliefs when the initial evidence for them is removed or
when they have been sharply contradicted. This belief perseverance effect has been first demonstrated experimentally by Festinger, Riecken, and Schachter. These psychologists spent time with
a cult whose members were convinced that the world would end on 21
December 1954. After the prediction failed, most believers still clung
to their faith. Their book describing this research is aptly named When Prophecy Fails.
The term belief perseverance, however, was coined in a
series of experiments using what is called the "debriefing paradigm":
participants read fake evidence for a hypothesis, their attitude change
is measured, then the fakery is exposed in detail. Their attitudes are
then measured once more to see if their belief returns to its previous
level.
A common finding is that at least some of the initial belief remains even after a full debriefing. In one experiment, participants had to distinguish between real and
fake suicide notes. The feedback was random: some were told they had
done well while others were told they had performed badly. Even after
being fully debriefed, participants were still influenced by the
feedback. They still thought they were better or worse than average at
that kind of task, depending on what they had initially been told.
In another study, participants read job performance ratings of two firefighters, along with their responses to a risk aversion test. This fictional data was arranged to show either a negative or positive
association: some participants were told that a risk-taking firefighter
did better, while others were told they did less well than a risk-averse
colleague. Even if these two case studies were true, they would have been
scientifically poor evidence for a conclusion about firefighters in
general. However, the participants found them subjectively persuasive. When the case studies were shown to be fictional, participants' belief
in a link diminished, but around half of the original effect remained. Follow-up interviews established that the participants had understood
the debriefing and taken it seriously. Participants seemed to trust the
debriefing, but regarded the discredited information as irrelevant to
their personal belief.
The continued influence effect
is the tendency for misinformation to continue to influence memory and
reasoning about an event, despite the misinformation having been
retracted or corrected. This occurs even when the individual believes
the correction.
Preference for early information
Experiments have shown that information is weighted more strongly
when it appears early in a series, even when the order is unimportant.
For example, people form a more positive impression of someone described
as "intelligent, industrious, impulsive, critical, stubborn, envious"
than when they are given the same words in reverse order. This irrational primacy effect is independent of the primacy effect in memory in which the earlier items in a series leave a stronger memory trace. Biased interpretation offers an explanation for this effect: seeing the
initial evidence, people form a working hypothesis that affects how
they interpret the rest of the information.
One demonstration of irrational primacy used colored chips
supposedly drawn from two urns. Participants were told the color
distributions of the urns, and had to estimate the probability of a chip
being drawn from one of them. In fact, the colors appeared in a prearranged order. The first thirty
draws favored one urn and the next thirty favored the other.
The series as a whole was neutral, so rationally, the two urns were
equally likely. However, after sixty draws, participants favored the urn
suggested by the initial thirty.
Another experiment involved a slide show of a single object, seen
as just a blur at first and in slightly better focus with each
succeeding slide. After each slide, participants had to state their best guess of what
the object was. Participants whose early guesses were wrong persisted
with those guesses, even when the picture was sufficiently in focus that
the object was readily recognizable to other people.
Illusory correlation is the tendency to see non-existent correlations in a set of data. This tendency was first demonstrated in a series of experiments in the late 1960s. In one experiment, participants read a set of psychiatric case studies, including responses to the Rorschach inkblot test.
The participants reported that the homosexual men in the set were more
likely to report seeing buttocks, anuses or sexually ambiguous figures
in the inkblots. In fact the fictional case studies had been constructed
so that the homosexual men were no more likely to report this imagery
or, in one version of the experiment, were less likely to report it than
heterosexual men. In a survey, a group of experienced psychoanalysts reported the same set of illusory associations with homosexuality.
Another study recorded the symptoms experienced by arthritic
patients, along with weather conditions over a 15-month period. Nearly
all the patients reported that their pains were correlated with weather
conditions, although the real correlation was zero.
Example
Days
Rain
No rain
Arthritis
14
6
No arthritis
7
2
This effect is a kind of biased interpretation, in that objectively
neutral or unfavorable evidence is interpreted to support existing
beliefs. It is also related to biases in hypothesis-testing behavior. In judging whether two events, such as illness and bad weather, are correlated, people rely heavily on the number of positive-positive
cases: in this example, instances of both pain and bad weather. They
pay relatively little attention to the other kinds of observation (of no
pain or good weather). This parallels the reliance on positive tests in hypothesis testing. It may also reflect selective recall, in that people may have a sense
that two events are correlated because it is easier to recall times when
they happened together.
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