Confirmation bias, also called confirmatory bias, myside bias, or congeniality bias, can lead to poor decision-making as it distorts the reality from which we draw evidence. When observed under experimental conditions, assigned decision-makers have a tendency to actively seek and assign greater value to information that confirms their existing beliefs rather than to evidence that entertains new ideas. This tendency can shape our everyday judgments and decisions in various ways.

Cognitive distortions and flawed beliefs

When forming judgments, confirmation bias causes us to selectively gather information based on what we already believe. Because this often occurs unconsciously, it can shape how we see the world completely outside our awareness. Even when we encounter evidence that might contradict our beliefs, we tend to interpret this new information in a way that still supports what we think. This can lead to some significant flaws and inconsistencies in our beliefs. 

For instance, someone who believes in the efficacy of a certain diet might discredit research showing that it’s ineffective, even if they generally value an evidence-based approach to nutrition. Similarly, a socially conscious shopper might continue shopping from a favorite fast-fashion retailer, focusing on brand messaging around sustainability while downplaying media reports about textile waste or labor conditions. As you can see from these examples, confirmation bias can create discrepancies between our values and actions, even if we’re completely unaware of this mismatch.

Effects on our personal relationships

Confirmation bias can also have implications for our interpersonal relationships. Specifically, first impressions can cause us to selectively attend to our peers’ subsequent behavior. Once we have formed an expectation about a person based on our initial social interaction, we may unconsciously seek information that reinforces our expectations through our later interactions with them. In doing so, we can appear closed-minded or, conversely, participate in relationships that do not serve us. 

For example, imagine you hold a negative impression of someone you recently met because they said something that left a bad taste in your mouth. When you encounter this person again, you may selectively focus on their flaws while ignoring their positive qualities.⁸ Likewise, if you believe your partner is lazy, you may notice more of those frustrating moments when they leave their laundry on the floor or fail to replace the toilet paper roll while ignoring all the times they’ve picked up the vacuum or made you coffee in the morning. Of course, this effect doesn’t just work in one direction. On the flip side, confirmation bias can cause us to idealize new partners, focusing on positive traits and downplaying red flags or incompatibilities that may derail the relationship down the road.

Confirmation bias in professional contexts

Confirmation bias can also pop up in the workplace, and not just when it comes to evaluating the personal qualities of your coworkers. The bias can make it difficult to see past your preconceived beliefs about a number of work-related issues, whether regarding who is best suited to lead a project, which ideas are worth pursuing in a meeting, or where to pick up donuts for the office party. Research shows that confirmation bias can also have a troubling influence on hiring practices. For instance, job applicants with accents or ethnic names are often viewed less positively by interviewers.⁹ During job interviews, this preconception causes human resources (HR) employees to elicit information consistent with their negative impression while ignoring information pointing to the candidate's job suitability. As a result, qualified candidates may be overlooked entirely.

Considering the bigger picture, confirmation bias can have serious implications. Major social divides and stalled policy-making may begin with our tendency to favor information that confirms our existing beliefs and ignore evidence that does not. 

Echo chambers and mass delusions

The more we become entrenched in our preconceptions, the greater the influence confirmation bias has on our behavior and, consequently, the people we choose to surround ourselves with. We can trap ourselves in a sort of echo chamber, and without being challenged, our biased thoughts prevail. This can lead to the spread of collective delusions in which groups of individuals reinforce beliefs that diverge from reality—think ancient witch hunts, the Satanic panic of the 1980s, and modern-day conspiracy theories. 

Today, social media allows delusional ideas to spread rapidly in echo chambers, where—walled off from dissenting viewpoints—false information and fake news stories gain credibility simply because these perspectives feel like the prevailing norm.¹⁰ This can be especially concerning in terms of socio-political cooperation and unity among the population.

Social division

Confirmation bias can also exacerbate social exclusion and tensions. In-group bias is the tendency to favor those with whom you identify, assigning them positive characteristics. That same inclination is not present for the out-group, which consists of individuals with whom you feel you share less in common. Combined with confirmation bias, there is a significant opportunity for prejudgment and stereotyping. Confirmation bias may lead us to look for favorable traits in our in-group and avoid any of our shortcomings. It may also cause us to be wary of the out-group and interpret their behavior through the lens of what we already assume. 

Unsurprisingly, confirmation bias plays a significant role in group polarization, in which groups adopt stances on issues that skew more extreme than the original positions of individual group members.¹¹ Group polarization often occurs in spaces where people gather and discuss shared opinions. During these discussions, group members selectively pay attention to information that supports their beliefs, amplifying these opinions and muting opposing views. As a result, individuals tend to adopt more extreme versions of their existing beliefs, which may have originally been more moderate or nuanced. When you consider how these group discussions have been amplified by social media, it’s no surprise that political beliefs have become much more polarized in recent decades.

Biased media algorithms

Confirmation bias is particularly present in the consumption of news and media. The ever-evolving ease of access has allowed the population to personally curate what they consume—and often, media algorithms lend a helping hand in ensuring we only see what we want to see. While it is evident that people cling to sources that support their political orientation, confirmation bias can also influence how news is reported. Journalists and media outlets are not immune to bias; they too are selective with their sources, what they choose to present, and how that information is conveyed.² Zooming out, these outlets and their leanings can have a strong influence on consumers’ knowledge, beliefs, and even voting patterns.  

Confirmation bias is a cognitive shortcut we use when gathering and interpreting information. Evaluating evidence takes time and energy, and so our brains look for shortcuts to make the process more efficient.

Confirmation bias is aided by several processes that all act on different stages of information processing to protect the individual from cognitive dissonance, or the discomfort associated with the violation of one’s beliefs. These processes include:

• Selective Exposure: The filtering of information in which the individual avoids all challenging or contradictory information.
• Selective Perception: When the individual observes or is exposed to information that conflicts with their existing beliefs, yet somehow interprets the information to affirm their existing views.
• Selective Retention: A major principle in marketing, demonstrating that individuals are more likely to remember information that has been presented to them if it is consistent with what they already know to be true.³

Our brains use shortcuts

Heuristics are the mental shortcuts that we use for efficient, though sometimes inaccurate, decision-making. Though it is debated whether or not confirmation bias can be categorized as a heuristic, it is certainly a cognitive strategy. Specifically, it helps us to avoid cognitive dissonance by searching for and attending to information that we already believe.  

It makes sense that we do this. Oftentimes, humans need to make sense of information quickly; however, forming new explanations or beliefs takes time and effort. We have adapted to take the path of least resistance, sometimes out of necessity.

Imagine our ancestors hunting. An intimidating animal is charging toward them, and they only have a few seconds to decide whether to hold their ground or run. There is no time to consider all the different variables involved in a fully informed decision. Past experience and instinct might cause them to look at the size of the animal and run. However, the presence of other hunters now tilts the chances of surviving the conflict in their favor. Evolutionary psychologists believe that the modern use of mental shortcuts for in-the-moment decision-making is based on past survival instincts.¹ 

It makes us feel good about ourselves

No one likes to be proven wrong, and when information is presented that violates our beliefs, it is only natural to push back. Deeply held views often form our identities, so disproving them can be uncomfortable. We might even believe that being wrong suggests that we lack intelligence. As a result, we often look for information that supports rather than refutes our existing beliefs.

We can also see the effects of confirmation bias in group settings. Clinical psychologist Jennifer Lerner, in collaboration with political psychologist Phillip Tetlock, proposed that through our interactions with others, we update our beliefs to conform to the group norm.  The psychologists distinguished between “confirmatory thought,” which seeks to rationalize a certain belief, and “exploratory thought,” which takes into consideration many viewpoints before deciding where you stand. 

Confirmatory thought in interpersonal settings can produce groupthink, in which the desire for conformity results in dysfunctional decision-making. So, while confirmation bias is often an individual phenomenon, it can also take place in groups of people.

As mentioned above, confirmation bias can be expressed individually or in a group context. Both can be problematic and deserve careful attention.

At the individual level, confirmation bias affects our decision-making. Our choices cannot be fully informed if we are only focusing on evidence that confirms our assumptions. Confirmation bias causes us to overlook pivotal information, both in our careers and in everyday life. A poorly informed decision is likely to produce suboptimal results because not all of the potential alternatives have been explored.  

A voter might stand by a candidate while dismissing emerging facts about the candidate’s poor behavior. A business executive might fail to investigate a new opportunity because of a negative experience with similar ideas in the past. An individual who sustains this sort of thinking may be labeled “closed-minded.”  Confirmation bias can cause us to miss out on opportunities and make less informed choices. Therefore, it is important to approach situations—and the decisions they call for—with an open mind. 

At a group level, it can produce and sustain the groupthink phenomenon. In a culture of groupthink, decision-making can be hindered by the assumption that harmony and group coherence are the values most crucial to success. This reduces the likelihood of disagreement within the group.

Imagine if an employee at a technology firm did not disclose a revolutionary discovery she had made for fear of reorienting the firm’s direction. Likewise, this bias can prevent people from becoming informed on differing views, and by extension, engaging in the constructive discussion that many democracies are built on.

Confirmation bias is likely to occur when we are gathering information for decision-making. It occurs subconsciously, meaning that we are unaware of its influence on our decision-making.

As such, the first step to avoiding confirmation bias is being aware that it is a problem. By understanding its effect and how it works, we are more likely to identify it in our own decision-making. Psychology professor and author Robert Cialdini suggests two approaches to recognizing when these biases are influencing our decision-making:

First, listen to your gut feeling. We often have a physical reaction to uncomfortable stimuli, like when a salesperson is pushing us too far. Even if we have complied with similar requests in the past, we should not use that precedent as a reference point. Recall past actions and ask yourself: “Knowing what I know now, if I could go back in time, would I make the same commitment?”

Second, because the bias is most likely to occur early in the decision-making process, we should focus on starting with a neutral fact base. This can be achieved by diversifying where we get our information and having multiple sources. Though it is difficult to find objective reporting, reaching for reputable, neutral outlets can allow us to have more agency in our beliefs. 

Third, when hypotheses are being drawn from assembled data, decision-makers should also consider having interpersonal discussions that explicitly aim at identifying individual cognitive biases in the hypothesis selection and evaluation. Engaging in debate is a productive way to challenge our views and expose ourselves to information we may have otherwise avoided. 

While it is likely impossible to eliminate confirmation bias completely, these measures may help manage it and make better decisions in light of it.

Is confirmation bias a logical fallacy?

Cognitive biases, like confirmation bias, are often confused with logical fallacies, but they are closer to mental shortcuts than formal errors in reasoning. Confirmation bias reflects just one way the human brain functions to help us make decisions quickly and efficiently—especially under uncertainty—but it is not a reasoning flaw in itself. Logical fallacies, on the other hand, are specific reasoning errors that invalidate arguments.¹³ Interestingly, confirmation bias can cause us to make logical errors in our arguments. For example, cherry-picking information that supports your argument while ignoring contradicting evidence is a logical fallacy, and this is often done unintentionally due to confirmation bias. 

Confirmation bias can also lead to circular reasoning: a logical fallacy in which the person making the argument begins with the conclusion they are trying to reach. For example, arguing that someone is guilty because they are accused of a crime or concluding that a diet is popular because everyone follows it.¹⁴ These arguments are not supported with any real evidence, but simply loop back to the initial conclusion. Confirmation bias can result in circular reasoning because it causes the reasoner to favor information that supports their existing beliefs. This narrow focus prevents a thorough evaluation of the argument, making the claim appear self-evident.

How does the irrational primacy effect impact confirmation bias?

Not to be confused with the standard primacy effect, where we’re more likely to remember items at the beginning of a list, the irrational primacy effect describes how we place more importance on initial information. For example, research shows that people form a more positive impression of someone described as “intelligent, industrious, impulsive, critical, stubborn, and envious” than when they are described with the same words in the reverse order.¹⁵ Generally, the irrational primacy effect causes us to disproportionately favor evidence that supports our early impressions, even if these impressions were inaccurate. Flawed judgments rooted in the effect are often supercharged by confirmation bias—where we actively seek out or interpret new information in a way that aligns with our existing beliefs—creating a cycle of biased thinking.

How can confirmation bias affect our memory?

Confirmation bias often distorts our understanding of past events by causing us to selectively remember information that aligns with our existing beliefs. This effect occurs because confirmation bias influences what we pay attention to, and therefore affects what information is stored in our memory, how it’s encoded, and how easily we retrieve it. Overall, information that is congruent with our existing knowledge is remembered better than information that refutes it.¹⁶ 

According to the schema theory of memory, we use knowledge structures built around our past experiences (called schemas) to interpret new information. When we encounter something new that fits with an existing schema, it’s easily encoded into our memory. Information that doesn’t fit as perfectly is more easily forgotten. Schemas are also activated when retrieving information; new information can serve as retrieval cues that shape what we pull from memory, so our recollection is often biased toward information that fits with our existing knowledge structures.

A well-known, excellent example of selective recall driven by confirmation bias comes from a study in which participants read about a woman going about her day, displaying a mix of introverted and extroverted behaviors.¹⁷ Later, one group of participants was told they were assessing the woman for a librarian position, while another group was told it was for a real estate job. As a result, the “librarian” group recalled more examples of introverted behavior from the list, while the “sales” group remembered more extroverted behavior. Because the woman’s introverted behavior fit with the schema that “librarians are quiet” and her extroverted behavior fit with the schema that “salespeople are extroverted,” participants’ memory retrieval was biased in a way that confirmed those expectations.

Can confirmation bias lead to discrimination?

Unfortunately, confirmation bias frequently contributes to discrimination. In social interactions, confirmation bias can cause people to favor information that aligns with stereotypes, as these preconceived beliefs often shape how individuals interpret social reality. As a result, people might dismiss evidence that suggests their beliefs are wrong, even if this is done completely unintentionally. 

For example, employers who hold inaccurate beliefs about a group—such as that members of a certain race or gender are less productive—may fail to properly revise their beliefs when confronted with evidence that suggests otherwise.¹⁸ Over time, as managers learn more about their workers’ productivity, they tend to interpret these signals as more consistent with their original stereotypes than they actually are. This can lead to persistent wage suppression, as workers from stereotyped groups continue to be underpaid, even if their actual productivity matches that of other employees.

Confirmation bias was known to the ancient Greeks. It was described by the classical historian Thucydides, in his text The History of the Peloponnesian. He wrote: “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 want.’’⁴

In the 1960s, Peter Wason first described this phenomenon as confirmation bias. In what’s known as Wason’s Selection Test, he conducted an experiment in which participants were presented with four cards. The cards were either red or brown and featured a number on the opposite side, two even, and two odd cards. For example, two cards would read the numbers 3 and 8, while the other two would be face down, showing the color, one red and one brown. Participants were told if the number on the card was even, the opposite side would be red. They were then tasked with trying to figure out whether this rule was true by flipping over two cards of their choosing. 

Many of the participants chose to turn over the card with the number 8 as well as the red card, as this was consistent with the rule they were given. In reality, this does little to actually test the rule. Indeed, turning over the “8” card will confirm what the experimenter said, but one also needs to turn over the brown card to verify that it is an odd number.

This experiment demonstrates confirmation bias in action; we seek to confirm what we know to be true while disregarding information that could potentially violate our assumptions.⁵ Several other studies have since discovered that our hypothesis-testing behavior tends to be fairly one-sided—we often search for evidence that would confirm a hypothesis rather than evaluating all the evidence available.¹² 

Marketing and reviews are where we can see the largest influence of confirmation bias as it pertains to products. Most consumers rely on product reviews and advertisements to advise them on the benefits of various items. For example, influencers and celebrities are commonly used to promote products. This can expose new people to the brand and broaden the customer demographic. However, it is important to be careful about who you allow to be part of your promotional campaign. By using controversial figures to recommend your product, you may be damaging the brand’s reputation. If any of your clients think poorly of the individual you endorsed, their first impression of your company will be a negative one. This is confirmation bias at work: if we dislike a celebrity who endorses a product, we are more likely to attend to information that suggests we will also dislike the product.

Consumers will often consult reviews before buying a product—this gives them a good idea of whether or not that item will be useful and valuable. Upon researching, if they are primed with an abundance of positive reviews, they may be more likely to seek to confirm information when using it themselves. 

When using artificial intelligence, we are in control of how we prompt the system. While these tools are meant to produce unbiased and objective information, the individual using them may steer the response in a direction that coincides with their preexisting beliefs. For example, if you are using AI software to research different political candidates, the manner in which you ask the question matters. Depending on the tool you use, “Why should I vote for X instead of Y” and “What are the strengths of X candidate and Y candidate” will turn up very different results. Depending on what we “want to hear,” we may unconsciously prompt the system to reinforce our initial thought pattern.

As mentioned, though we like to think of AI as unbiased, the reality may be a little murkier. Artificial intelligence uses large data sets to inform itself on various topics. Due to the size and comprehensiveness of these data sets, they may reflect the biases that are present in the world around us. While it may be harmless in certain situations, it can also perpetuate negative stereotypes, or push a certain narrative as a result of the data used to program it. 

A major study carried out by researchers at Stanford University in 1979 explored the psychological dynamics of confirmation bias. The study was composed of undergraduate students who held opposing viewpoints on the topic of capital punishment. Unbeknownst to them, the participants were asked to evaluate two fictitious studies on the topic.

One of the false studies provided data in support of the argument that capital punishment deters crime, while the alternative study supported the opposing view—that capital punishment had no appreciable effect on overall criminality in the population.

While both studies were entirely fabricated by the Stanford researchers, they were designed to present “equally compelling” objective statistics. The researchers discovered that responses to the studies were heavily influenced  by participants’ pre-existing opinions:

• The participants who initially supported the deterrence argument in favor of capital punishment considered the anti-deterrence data unconvincing and thought the data in support of their position was credible.
• Participants who held the opposing view at the beginning of the study reported the same, but in support of their stance against capital punishment.

So, after being confronted with both evidence that supported capital punishment and evidence that refuted it, both groups reported feeling more committed to their original stance. The net effect of having their position challenged was a re-entrenchment of their existing beliefs.⁶

The “filter bubble” effect is an example of technology amplifying and facilitating our cognitive tendency toward confirmation bias. The term was coined by internet activist Eli Pariser to describe the intellectual isolation that can occur when websites use algorithms to predict and present information a user would want to see.⁷

This means that as we use particular websites and content networks, the more likely we are to encounter content that we prefer. At the same time, algorithms will exclude content that runs contrary to our preferences. We normally prefer content that confirms our beliefs because it requires less critical reflection. So, filter bubbles might favor information that confirms your existing opinions and exclude disconfirming evidence from your online experience.

In his seminal book, The Filter Bubble: What the Internet Is Hiding from You, Pariser uses the example of internet searches for an oil spill to show the filter bubble effect:

"In the spring of 2010, while the remains of the Deepwater Horizon oil rig were spewing crude oil into the Gulf of Mexico, I asked two friends to search for the term ‘BP’. They’re pretty similar—educated, white, left-leaning women who live in the Northeast. But the results they saw were quite different. One of my friends saw investment information about BP. The other saw the news. For one, the first page results contained links about the oil spill; for the other, there was nothing about it except for a promotional ad from BP."⁷

If this were the only source of information that these women were exposed to, surely they would have formed very different conceptions of the BP oil spill. The internet search engine showed information tailored to the beliefs their past searches showed and picked results predicted to fit with their reaction to the oil spill. Unbeknownst to them, it facilitated confirmation bias.

While the implications of this particular filter bubble may have been harmless, filter bubbles on social media platforms have been shown to influence elections by tailoring the content of campaign messages and political news to different subsets of voters. This could have a fragmenting effect that inhibits constructive democratic discussion, as different voter demographics become increasingly entrenched in their political views as a result of a curated stream of evidence that supports them.

What it is

Confirmation bias describes our underlying tendency to notice, focus on, and give greater credence to evidence that fits with our existing beliefs.

Why it happens

Confirmation bias is a cognitive shortcut we use when gathering and interpreting information. Evaluating evidence takes time and energy, and so our brains looks for shortcuts to make the process more efficient. We look for evidence that best supports what we know to be true because the most readily available hypotheses are the ones we already have. Another reason we sometimes show confirmation bias is that it protects our self-esteem. No one likes feeling bad about themselves—and realizing that a belief they valued is false can have this effect. As a result, we often look for information that supports rather than disproves our existing beliefs.

Example #1 - Blindness to our own faults

A 1979 study by researchers at Stanford found that after being confronted with equally compelling evidence in support of capital punishment and evidence that refuted it, participants reported feeling more committed to their original stance on the issue. The net effect of having their position challenged was a re-entrenchment of their existing beliefs.

Example #2 - Establishing personalized networks online

Modern preference algorithms have a “filter bubble” effect, which is an example of technology amplifying and facilitating our tendency toward confirmation bias. Websites use algorithms to predict the information and content that a user wants to see. We normally prefer media that confirms our beliefs because it requires less critical reflection. So, filter bubbles might exclude information that clashes with your existing opinions, as informed by your online activity. 

How to avoid it

Confirmation bias is likely to occur when we are gathering information needed to make decisions. It is also subconscious, meaning we are unaware of its influence on our decision-making. As such, the first step to avoiding confirmation bias is being aware of it. Because confirmation bias is most likely to occur early in the decision-making process, we should focus on starting with a neutral fact base. This can be achieved by having multiple objective sources of information.

Can Overcoming Implicit Gender Bias Boost a Company’s Bottom Line? 

This article argues that gender diversity in a firm is associated with higher performance. By addressing and drawing on confirmation bias (among other relevant psychological principles), firms may be able to increase diversity and thereby increase performance.

Learning Within Limits: How Curated Content Affects Education 

This article argues that the use of “trigger warnings,” modern preference algorithms, and other such cues create a highly curated stream of information that facilitates cognitive biases such as confirmation bias. The author notes that this can prevent us from empathizing with others and revising our opinions in light of differing ones.