Confirmation bias | Definition, Examples, Psychology, & Facts

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class="md-content"> <div class="md-article-container template-desktop"> <div class="infinite-scroll-container article last"> <article class="article-content container-lg qa-content px-0 pt-0 pb-40 py-lg-20 content md-expanded" data-topic-id="2073711"> <div class="grid gx-0"> <div class="col-auto"> <div class="topic-left-rail md-article-drawer position-relative d-flex border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/confirmation-bias">confirmation bias</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/confirmation-bias">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref334973"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/confirmation-bias#ref334973">Background</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref334974"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/confirmation-bias#ref334974">Evidence</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref334975"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/confirmation-bias#ref334975">Importance</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref334976"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/confirmation-bias#ref334976">Implications</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/confirmation-bias/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/confirmation-bias">Related Topics</a> </div> <div class="mb-30 tlr-discover"> <div class="text-gray-900 p-5 font-serif font-14 font-weight-bold mx-10 mb-10"> Discover </div> <div class="imagelink-with-image-on-the-side card card-horizontal 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Casad</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Assistant Professor, Department of Psychological Sciences, University of Missouri–St. Louis. Her contributions to SAGE Publications's <em>Encyclopedia of Social Psychology</em> (2007) formed the basis...</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Bettina J. Casad</span>, <div class="editor-popover popover p-0"> <a class="d-block p-20 gtm-byline font-12 byline-contributor" href="/editor/JE-Luebering/6492" > <div class="editor-title font-16 font-weight-bold">J.E. Luebering</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">J.E. Luebering is Vice President, Editorial at Encyclopaedia Britannica.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> J.E. Luebering</span><span class="text-gray-700 mx-5">•</span><a class="see-all border-gray-700 gtm-byline" rel="nofollow" href="https://www.britannica.com/science/confirmation-bias/additional-info#contributors">All</a> </div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2024-10-22T00:00:00CDT" >Oct 22, 2024</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/confirmation-bias/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/cognitive-bias" topicid="2221238">cognitive bias</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/confirmation-bias"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref1235345"></span>confirmation bias</strong>, people’s tendency to process information by looking for, or interpreting, information that is consistent with their existing beliefs. This <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="biased" href="https://www.merriam-webster.com/dictionary/biased" data-type="MW">biased</a> approach to <a href="https://www.britannica.com/topic/decision-making" class="md-crosslink " data-show-preview="true">decision making</a> is largely unintentional, and it results in a person ignoring information that is inconsistent with their beliefs. These beliefs can include a person’s expectations in a given situation and their predictions about a particular outcome. People are especially likely to process information to support their own beliefs when an issue is highly important or self-relevant.</p><span class="marker MOD1 mod-inline"></span></section> <span class="marker h2"></span><section data-level="1" id="ref334973"> <h2 class="h1">Background</h2> <span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Confirmation bias is one example of how humans sometimes process information in an illogical, biased manner. The manner in which <a href="https://www.britannica.com/topic/epistemology" class="md-crosslink " data-show-preview="true">a person knows and understands the world</a> is often affected by factors that are simply unknown to that person. Philosophers note that people have difficulty processing information in a <a href="https://www.britannica.com/topic/rationality" class="md-crosslink " data-show-preview="true">rational</a>, <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="unbiased" href="https://www.britannica.com/dictionary/unbiased" data-type="EB">unbiased</a> manner once they have developed an <a href="https://www.britannica.com/topic/belief" class="md-crosslink autoxref " data-show-preview="true">opinion</a> about an issue. Humans are better able to rationally process information, giving equal weight to multiple viewpoints, if they are <a href="https://www.britannica.com/science/emotion" class="md-crosslink " data-show-preview="true">emotionally</a> distant from the issue (although a low level of confirmation bias can still occur when an individual has no vested interests).</p><span class="marker MOD2 mod-inline"></span> <span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph"><em><a href="https://www.britannica.com/topic/rationality" class="md-crosslink " data-show-preview="true">(Read Steven Pinker’s Britannica entry on rationality.)</a></em></p><div class="module-spacing"> </div><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">One explanation for why people are susceptible to confirmation bias is that it is an efficient way to process information. Humans are incessantly bombarded with information and cannot possibly take the time to carefully process each piece of information to form an unbiased conclusion. Human decision making and <a href="https://www.britannica.com/technology/information-processing" class="md-crosslink " data-show-preview="true">information processing</a> is often biased because people are limited to interpreting information from their own viewpoint. People need to process information quickly to protect themselves from harm. It is <a href="https://www.britannica.com/science/adaptation-biology-and-physiology" class="md-crosslink " data-show-preview="true">adaptive</a> for humans to rely on <a href="https://www.britannica.com/science/reflex-physiology" class="md-crosslink " data-show-preview="true">instinctive, automatic behaviours</a> that keep them out of harm’s way.</p><span class="marker MOD4 mod-inline"></span> <span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">Another <a href="https://www.britannica.com/topic/reason" class="md-crosslink autoxref " data-show-preview="true">reason</a> why people show confirmation bias is to protect their <a href="https://www.britannica.com/science/self-esteem" class="md-crosslink " data-show-preview="true">self-esteem</a>. People like to feel good about themselves, and discovering that a belief that they highly value is incorrect makes them feel bad about themselves. Therefore, people will seek information that supports their existing beliefs. Another closely related motive is wanting to be correct. People want to feel that they are intelligent, but information that suggests that they are wrong or that they made a poor decision suggests they are lacking intelligence—and thus confirmation bias will encourage them to disregard this information.</p><span class="marker MOD5 mod-inline"></span> </section> <span class="marker h3"></span><section data-level="1" id="ref334974"><h2 class="h1">Evidence</h2> <span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Research has shown that confirmation bias is strong and widespread and that it occurs in several <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="contexts" href="https://www.merriam-webster.com/dictionary/contexts" data-type="MW">contexts</a>. In the <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="context" href="https://www.merriam-webster.com/dictionary/context" data-type="MW">context</a> of <a href="https://www.britannica.com/topic/decision-making" class="md-crosslink " data-show-preview="true">decision making</a>, once an individual makes a decision, they will look for information that supports it. Information that conflicts with a person’s decision may cause discomfort, and the person will therefore ignore it or give it little consideration. People give special treatment to information that supports their personal beliefs. In studies examining <em>my-side bias</em>, people were able to generate and remember more reasons supporting their side of a controversial issue than the opposing side. Only when a researcher directly asked people to generate arguments against their own beliefs were they able to do so. It is not that people are incapable of generating arguments that are counter to their beliefs, but, rather, people are not motivated to do so.</p><span class="marker MOD6 mod-inline"></span> <span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">Confirmation bias also surfaces in people’s tendency to look for positive instances. When seeking information to support their <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="hypotheses" href="https://www.merriam-webster.com/dictionary/hypotheses" data-type="MW">hypotheses</a> or expectations, people tend to look for positive <a href="https://www.britannica.com/topic/evidence-law" class="md-crosslink autoxref " data-show-preview="true">evidence</a> that confirms that a <a href="https://www.britannica.com/science/hypothesis" class="md-crosslink " data-show-preview="true">hypothesis</a> is true rather than information that would prove the view is false (if it is false).</p><div class="module-spacing"> <DIV class="marketing-INLINE_SUBSCRIPTION marketing-content" data-marketing-id="INLINE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Get Unlimited Access</div> <div class="h4 font-weight-semi-bold">Try Britannica Premium for free and discover more.</div> </div> <div class="student-promo-banner-button-wrapper d-flex justify-content-center align-items-center ml-auto mr-auto"> <a class="btn btn-m btn-orange" href="https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=black-friday-2024">Subscribe</a> </div> </div> </div> </DIV></div><span class="marker MOD7 mod-inline"></span> <span class="marker PREMOD8 mod-inline"></span><p class="topic-paragraph">Confirmation bias also operates in impression formation. If people are told what to expect from a person they are about to meet, such as that the person is warm, friendly, and outgoing, people will look for information that supports their expectations. When interacting with people whom perceivers think have certain personalities, the perceivers will ask questions of those people that are biased toward supporting the perceivers’ beliefs. For example, if Maria expects her roommate to be friendly and outgoing, Maria may ask her if she likes to go to parties rather than asking if she often studies in the library.</p><span class="marker MOD8 mod-inline"></span></section> <span class="marker h4"></span><section data-level="1" id="ref334975"><h2 class="h1">Importance</h2> <span class="marker PREMOD9 mod-inline"></span><p class="topic-paragraph">Confirmation bias is important because it may lead people to hold strongly to false beliefs or to give more weight to information that supports their beliefs than is warranted by the evidence. People may be overconfident in their beliefs because they have accumulated evidence to support them, when in reality they have overlooked or ignored a great deal of evidence refuting their beliefs—evidence which, if they had considered it, should lead them to question their beliefs. These factors may lead to risky decision making and lead people to overlook warning signs and other important information. In this manner, confirmation bias is often a component of <a href="https://www.britannica.com/topic/black-swan-event" class="md-crosslink " data-show-preview="true">black swan events</a>, which are high-impact events that are unexpected but, <a href="https://www.britannica.com/topic/hindsight-bias" class="md-crosslink " data-show-preview="true">in retrospect</a>, appear to be inevitable.</p><span class="marker MOD9 mod-inline"></span></section> <span class="marker h5"></span><section data-level="1" id="ref334976"> <h2 class="h1">Implications</h2> <span class="marker PREMOD10 mod-inline"></span><p class="topic-paragraph">Confirmation bias has important <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="implications" href="https://www.merriam-webster.com/dictionary/implications" data-type="MW">implications</a> in the real world, including in medicine, law, and interpersonal relationships. Research has shown that medical doctors are just as likely to have confirmation biases as everyone else. Doctors often have a preliminary hunch regarding the <span id="ref1235354"></span><a href="https://www.britannica.com/science/diagnosis" class="md-crosslink " data-show-preview="true">diagnosis</a> of a medical condition early in the treatment process. This hunch can interfere with the doctor’s ability to assess information that may indicate an <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="alternative" href="https://www.merriam-webster.com/dictionary/alternative" data-type="MW">alternative</a> <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="diagnosis" href="https://www.merriam-webster.com/dictionary/diagnosis" data-type="MW">diagnosis</a> is more likely. Another related outcome is how patients react to <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="diagnoses" href="https://www.merriam-webster.com/dictionary/diagnoses" data-type="MW">diagnoses</a>. Patients are more likely to agree with a diagnosis that supports their preferred outcome than a diagnosis that goes against their preferred outcome. Both of these examples demonstrate that confirmation bias has implications for individuals’ health and well-being.</p><span class="marker MOD10 mod-inline"></span> <span class="marker PREMOD11 mod-inline"></span><p class="topic-paragraph">In the context of law, judges and jurors sometimes form an opinion about a defendant’s guilt or innocence before all of the evidence is known. Once a judge or juror forms an opinion, confirmation bias will interfere with their ability to process new information that emerges during a trial, which may lead to unjust verdicts.</p><div class="one-good-fact-module"> </div><span class="marker MOD11 mod-inline"></span> <span class="marker PREMOD12 mod-inline"></span><p class="topic-paragraph">In interpersonal relations, confirmation <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="bias" href="https://www.britannica.com/dictionary/bias" data-type="EB">bias</a> can be problematic because it may lead a person to form inaccurate and biased impressions of others. This may result in miscommunication and conflict in intergroup settings. In addition, when someone treats a person according to their expectations, that person may unintentionally change their behavior to conform to the other person’s expectations, thereby providing further support for the perceiver’s confirmation bias.</p><span class="marker MOD12 mod-inline"></span> <span class="md-signature"><a href="/contributor/Bettina-J-Casad/9782917">Bettina J. Casad</a></span> <span class="md-signature"><a href="/editor/JE-Luebering/6492">J.E. 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Confirmation bias | Definition, Examples, Psychology, & Facts | Britannica