Why do people fiercely defend their beliefs, dismiss contradictory evidence and sometimes turn disagreements into personal attacks? Consultant Psychiatrist Dr. Rumi Ruben examines the psychological forces behind confirmation bias and explains why it should not be mistaken for a mental illness.
Disagreements have become an unavoidable feature of social media. What begins as a difference of opinion can quickly deteriorate into an exchange of insults, personal attacks and accusations. At times, the determination to prove oneself right appears to matter more than discovering the truth.
Such confrontations raise an interesting psychological question: Is an unwillingness to accept another person’s opinion a sign of mental illness?
According to Consultant Psychiatrist Dr. Rumi Ruben, the answer requires an understanding of a common psychological tendency known as confirmation bias.
This tendency helps explain why people readily accept information that supports their existing beliefs while questioning, dismissing or rejecting evidence that challenges them.
Although confirmation bias can influence behaviour and decision-making, it is not, by itself, a psychiatric disorder.
Why Being Proven Right Feels So Satisfying
Most people experience a sense of satisfaction when they encounter information that confirms something they already believe.
Such information can provide reassurance, reinforce confidence and strengthen the feeling that their judgment was correct.
The reaction can be very different when they encounter evidence that contradicts an established belief.
Instead of examining the new information objectively, a person may ignore it, search for weaknesses in the argument or challenge the credibility of whoever presented it.
Sometimes, the disagreement becomes less about the evidence and more about discrediting the person offering an opposing view.
These reactions illustrate how existing beliefs can influence the way information is received and evaluated.
What Is Confirmation Bias?
Confirmation bias is the tendency to seek, interpret and remember information in ways that support beliefs a person already holds.
It can also involve giving less weight to contradictory evidence, even when that evidence deserves serious consideration.
The problem is not necessarily the information itself. It is the way the mind selects and evaluates that information.
Two people can encounter the same facts and arrive at strikingly different conclusions because each interprets the evidence through the influence of prior beliefs.
This tendency is not limited to people with strong political or religious opinions. It can affect almost anyone, including educated professionals and individuals who consider themselves rational and impartial.
Is Confirmation Bias a Mental Illness?
Dr. Ruben explains that confirmation bias is a cognitive tendency rather than a mental illness.
It occurs to varying degrees in ordinary human thinking and is studied in psychology as part of information processing, reasoning and decision-making.
Confirmation bias is not recognised as a separate psychiatric diagnosis in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), or the World Health Organization’s International Classification of Diseases.
Consequently, it would be inappropriate to conclude that someone has a mental illness simply because they refuse to reconsider an opinion or insist that their interpretation is correct.
An individual’s unwillingness to change a belief may be frustrating or damaging to relationships, but that behaviour alone does not establish the presence of a psychiatric disorder.
Nevertheless, confirmation bias can have serious consequences when it influences decisions involving health, scientific research, politics or other matters requiring careful judgment.
How the Human Mind Selects Information
The human mind does not evaluate every piece of information with equal attention or impartiality.
Information that agrees with familiar beliefs may be easier to accept. Information that challenges those beliefs can require greater effort to consider.
Past experiences, education, social background, emotional responses and personal identity can all influence how someone interprets what they see and hear.
Dr. Ruben identifies several ways this tendency can appear.
1. Searching Only for Supporting Evidence
A person may deliberately or unconsciously seek information that confirms an existing opinion while overlooking material that challenges it.
For example, someone convinced that a particular medical treatment is effective may focus on positive testimonials while ignoring research concerning its limitations or unsuccessful outcomes.
The resulting conclusion may appear well supported, although much of the available evidence has never been fairly considered.
2. Interpreting the Same Evidence Differently
The same event or piece of information can produce opposing interpretations.
Someone who strongly supports a political party may regard a particular Government decision as evidence of effective leadership.
A political opponent might interpret the same decision as evidence of failure.
The facts have not necessarily changed. What differs is the way each person interprets them.
3. Applying Unequal Standards to Evidence
Another form of confirmation bias involves examining contradictory evidence far more critically than supporting evidence.
A person may accept a favourable claim without checking its source but demand extensive proof when confronted with information that challenges their opinion.
They may also dismiss an argument by attacking the credibility or motives of the person presenting it.
When evidence is subjected to different standards depending on whether it supports an existing belief, the assessment becomes distorted.
4. Mistaking Repetition for Truth
Repeated exposure to the same claim can make it seem increasingly familiar and convincing.
However, repetition does not establish accuracy.
An assertion shared thousands of times does not become true merely because many people have encountered or endorsed it.
Familiarity and independent verification are two very different things.
What Scientific Research Reveals
Research published in the journal Cognition in 2024 examined how confirmation bias can arise during the process of updating beliefs.
The study, titled Confirmation Bias Emerges from an Approximation to Bayesian Reasoning, explored the relationship between existing beliefs, new evidence and judgments about the reliability of information sources.
Its findings help explain how people can give different weight to evidence depending on whether it supports or challenges their prior understanding.
The research also examined processes associated with belief perseverance, biased evaluation and the polarisation of opinions.
These findings illustrate how differences in the evaluation of evidence can persist and, under certain circumstances, deepen disagreements between people who begin with opposing beliefs.
Can Confirmation Bias Affect Doctors?
One of the more serious applications of confirmation bias arises in medical diagnosis.
A doctor examining a patient may initially suspect a particular illness based on the symptoms presented.
Forming an initial diagnosis or working hypothesis is a normal and necessary part of medical practice.
The problem arises if subsequent information is interpreted exclusively in ways that support that initial suspicion.
For example, later test results may point towards an alternative diagnosis. If the doctor disregards those findings because they conflict with the original assessment, the patient could receive an incorrect diagnosis or inappropriate treatment.
To reduce this risk, clinicians can use structured approaches to clinical reasoning, including the hypothetico-deductive method.
This involves developing possible explanations, testing them against available evidence and revising or rejecting them when the findings do not support the original hypothesis.
Professional qualifications and experience do not make someone entirely immune to cognitive bias.
Considering alternative diagnoses, reviewing contradictory findings and obtaining a second opinion when appropriate can therefore be important safeguards.
Social Media and the Echo Chamber Effect
Social media provides a particularly visible environment in which confirmation bias can operate.
People often choose to follow accounts, pages and commentators whose political, religious or social views resemble their own.
As a result, they may encounter a steady stream of information supporting their existing opinions while receiving comparatively little exposure to opposing arguments.
Recommendation systems can reinforce this pattern by suggesting content based on previous viewing habits, interactions and interests.
Someone who repeatedly watches videos supporting a particular viewpoint may consequently be shown more content expressing similar opinions.
Over time, this can create an environment in which an individual encounters relatively few challenges to their beliefs.
Such an environment is commonly described as an echo chamber.
However, social media algorithms should not be regarded as the sole cause of confirmation bias.
Individual choices, friendships, community relationships and wider social influences also determine which information people encounter.
Nor does every recommendation system necessarily intensify political or ideological division in the same way.
Nevertheless, repeated exposure to similar viewpoints can give individuals the impression that their opinions are universally accepted or unquestionably correct.
An idea’s popularity, however, is not proof of its accuracy.
When Emotions Influence Reasoning
Understanding confirmation bias also requires recognising the relationship between thinking and feeling.
Cognitive processes allow people to interpret information, reason, analyse evidence and make decisions.
Emotional processes involve experiences such as happiness, fear, anger, sadness, affection and jealousy.
Both contribute to ordinary human decision-making.
The difficulty arises when an emotional attachment to an existing belief interferes with a fair assessment of the evidence.
Admitting that a deeply held opinion may be wrong can produce discomfort, embarrassment or a feeling of personal defeat.
For some individuals, a challenge to their beliefs may also feel like a challenge to their intelligence, identity or membership of a particular social group.
Under those circumstances, anger, defensiveness or rejection may replace careful consideration.
This does not mean emotions completely eliminate rational thought. Rather, emotional reactions can influence which facts a person notices, how those facts are interpreted and whether contrary arguments receive a fair hearing.
Someone may sincerely believe they are reasoning objectively while being influenced by a desire to protect an existing conviction.
The Consequences for Families and Society
The effects of confirmation bias can extend beyond disagreements between strangers on social media.
Within families, an unwillingness to consider another person’s perspective may contribute to repeated arguments and misunderstandings.
A parent, spouse or partner who assumes that their opinion is always correct may struggle to recognise legitimate concerns raised by others.
Such behaviour can weaken communication and make disagreements increasingly difficult to resolve.
At a wider social level, confirmation bias can contribute to divisions between political, religious, cultural and ideological groups.
When members of a group accept only information supporting their collective beliefs, opposing viewpoints may be dismissed before they are properly examined.
Social media can make these divisions more visible by enabling rapid circulation of selective information, misleading claims and emotionally charged commentary.
In these circumstances, defending a position can become more important than determining whether it is accurate.
How Can People Overcome Confirmation Bias?
Dr. Ruben emphasises the importance of recognising that even a strongly held belief may be mistaken.
Overcoming confirmation bias does not require abandoning personal convictions or accepting every opposing argument.
It requires a willingness to evaluate evidence fairly, including evidence that challenges one’s existing position.
Several practical approaches can help.
Be Willing to Question Yourself
Before defending an opinion, consider whether there is credible evidence that could prove it wrong.
A willingness to reconsider does not demonstrate weakness. It reflects intellectual openness.
Examine the Source
Check where information originated, whether it is supported by reliable evidence and whether important context has been omitted.
Apply the same standards of scrutiny to information you agree with and information you oppose.
Consider Alternative Explanations
A single event can sometimes have several plausible explanations.
Before reaching a firm conclusion, examine whether another interpretation better accounts for the available facts.
Listen Without Immediately Responding
When encountering an opposing opinion, make an effort to understand the argument before preparing a rebuttal.
Listening does not require agreement. It creates an opportunity to assess the substance of the position being presented.
Recognise Emotional Reactions
Notice when a disagreement produces anger, embarrassment or defensiveness.
Such reactions may indicate that personal feelings are influencing the assessment of evidence.
Pausing before responding can help create space for more considered reasoning.
Accept That Changing Your Mind Is Not Defeat
Revising an opinion in response to convincing new evidence is an essential part of learning.
Scientific understanding, medical practice and responsible decision-making all depend on the willingness to reconsider earlier conclusions.
Maintaining an incorrect belief merely to avoid admitting a mistake serves neither the individual nor society.
Finding the Balance Between Thinking and Feeling
Emotions are an essential part of human life.
They influence relationships, compassion, empathy and the way people connect with one another. The objective is not to eliminate emotions from decision-making.
Rather, it is to recognise when emotional attachment may prevent a fair examination of facts.
The ability to combine reason with emotional awareness is especially important in an environment where opinions can be expressed instantly and opposing views are frequently treated as personal attacks.
Confirmation bias is a reminder that human judgment is not automatically impartial simply because it feels logical.
Understanding this tendency begins with a simple distinction: what we feel to be true is not necessarily true, and what we believe with certainty is not necessarily correct.
The willingness to acknowledge that difference may be the most important step towards more thoughtful decisions, healthier relationships and more constructive public debate.
Psychological analysis attributed to Consultant Psychiatrist Dr. Rumi Ruben.
