Preconceived notions are beliefs, assumptions, or expectations that people hold before encountering new evidence on a topic. Far from being a character flaw or a sign of laziness, they are a product of how the brain is wired: higher-order brain regions constantly generate predictions about incoming sensory data, and mismatches between those predictions and reality produce what neuroscientists call prediction errors.1PubMed Central. Predictive coding: a more cognitive process than we thought? This means the brain is not a passive recorder of the world but an active guesser, and preconceived notions are its guesses. The trouble starts when those guesses resist updating, even in the face of clear contradictory evidence.
How the Brain Builds Its Expectations
Your brain does not wait for raw information to arrive and then figure out what it means. Instead, it runs a constant loop: it predicts what it expects to see, hear, or feel, then checks those predictions against what actually shows up. When predictions match reality, processing is fast and efficient. When they don’t match, the brain flags a prediction error, a signal that something unexpected happened and needs attention. This framework, known as predictive coding, helps explain why preconceived notions feel so natural. They aren’t just opinions layered on top of perception; they are baked into perception itself.
Underneath this prediction machinery sit mental structures researchers call schemas. These are broad knowledge frameworks built from repeated experiences, and they shape how new events are perceived, interpreted, and remembered. A schema doesn’t store a single memory; it stores the pattern abstracted across many memories. Once a schema is active, it acts as a template that filters what you pay attention to and how you encode it. Research on the neurobiology of schemas shows that these templates can modulate early perceptual processing, meaning they influence what you notice before you’ve had time to consciously evaluate it.2Cell Press (Trends in Cognitive Sciences). The neurobiology of memory schemas Schemas can enhance accurate memory when the world cooperates with your expectations, but they also distort memory when reality departs from the template.
There is also an evolutionary logic at work. Visual systems across the animal kingdom have evolved to simplify complex environments through categorization, sorting continuously varying stimuli into discrete buckets, and specialization, processing certain types of information through dedicated cognitive channels.3Annual Reviews. The Evolution of Simplifying Heuristics in Visual Cognition: Categorization, Specialization, and Visual Illusions These shortcuts were essential for survival: an ancestor who waited to carefully analyze whether a shadow in the grass was a predator or a rock did not last long. But those same shortcuts now produce snap judgments and categorical thinking in situations where careful analysis would serve us better.
When Expectations Literally Change What You See and Hear
Preconceived notions don’t just shape how you interpret events after the fact. They alter what you perceive in the moment. One striking demonstration comes from research on multisensory perception. When people watch videos of someone speaking a syllable, and the audio doesn’t match the lip movements, the brain sometimes fuses the mismatched signals into an entirely new perceived syllable, a phenomenon called the McGurk effect. Critically, how often people experience this illusion depends on what they expect. When McGurk stimuli are embedded in a run of matching audiovisual syllables, people are more likely to fuse the mismatched signals into the illusory percept than when the same stimuli appear in a run of obviously mismatched syllables.4PubMed. How prior expectations shape multisensory perception In other words, the context of “things have been matching so far” creates an expectation that makes your brain fill in a perception that isn’t physically there.
This goes beyond laboratory illusions. A population-level study found that people who reported recent auditory hallucinations had a higher rate of false alarms in auditory language perception: they “heard” words that were not actually spoken. The more recently someone had experienced verbal hallucinations, the more false perceptions they registered.5PubMed Central. Auditory hallucinations, top-down processing and language perception: a general population study The researchers connected this to overactive top-down processing: when the brain’s prediction machinery is dialed up too high, it generates perceptions from expectations alone. This is an extreme case, but it illustrates a principle that applies to everyone on a smaller scale. The stronger your expectation, the more your brain is willing to perceive things that conform to it.
How Confirmation Bias Locks Preconceived Notions in Place
Even when contradictory information does reach the brain, it faces an uphill battle. Neuroimaging research has shown that information contradicting pre-existing beliefs has little impact on subsequent behavior, despite being precisely encoded in the brain.6PubMed Central. Confirmation Bias through Selective Readout of Information Encoded in Human Parietal Cortex The brain registers the contradictory evidence. It just doesn’t use it. This is one of the more unsettling findings in the study of preconceived notions: the problem is not always that disconfirming information is missed or misunderstood. Sometimes it’s encoded accurately and then quietly ignored during decision-making.
A complementary line of research has pinpointed a mechanism that may explain part of this. When people make an initial choice or judgment, their perceptual sensitivity to subsequent information shifts. Specifically, evidence that is consistent with the initial choice gets a boost in processing, while inconsistent evidence does not. This selective gain modulation happens even in simple perceptual tasks like judging the direction of moving dots, and it generalizes across different types of tasks, suggesting it’s a fundamental feature of how the brain processes sequential information.7PubMed. Confirmation Bias through Selective Overweighting of Choice-Consistent Evidence The implication is that once you form a preliminary opinion, your attention system begins doing favors for it, making confirming evidence feel sharper and more salient while disconfirming evidence fades into the background. This is not a deliberate strategy. It’s an automatic recalibration of perception by your own decision-making system.
Why Identity Makes Some Beliefs Almost Impossible to Shake
Not all preconceived notions resist change equally. Beliefs that are tied to a person’s sense of identity, their political tribe, religious community, professional reputation, or moral self-image, are especially tenacious. Research on identity-protective cognition shows that people are more likely to accept misinformation and resist having it corrected when the misinformation is identity-affirming rather than identity-threatening.8SSRN. Misconceptions, Misinformation, and the Logic of Identity-Protective Cognition When a false belief supports the worldview of a group you belong to, correcting it feels like an attack on the group itself, and by extension, on you.
This helps explain why debates about politically charged topics so often feel like talking past each other. The disagreement is not really about the facts. It’s about what accepting those facts would mean for each person’s social identity. A person who has built a sense of community and meaning around a particular stance will experience factual correction as a social threat, triggering defensive processing rather than open evaluation. This is why simply presenting “more data” to someone with a firmly held preconceived notion often backfires. The data is not landing in a neutral evaluative space; it’s landing in a space already structured by identity concerns.
How Children Develop Preconceived Notions
Preconceived notions are not something adults develop through years of experience and then regrettably cling to. The architecture for forming and applying them appears remarkably early. Research on conceptual change in children argues that a framework theory of the physical world is established in infancy, forming the basis of how children interpret observations and culturally transmitted information. When new scientific information contradicts the deep assumptions of that framework, children do not simply adopt the new view. Instead, they attempt to fit the new information into existing structures, which often produces misconceptions.9Learning and Instruction. Capturing and modeling the process of conceptual change This is why children (and adults) so often hold onto intuitive physics ideas, like the belief that heavier objects fall faster, even after formal instruction. The new information gets warped to fit the old framework rather than replacing it.
Social preconceptions develop early too. Research on the origins of social categorization shows that even infants use social categories to guide their inferences about other people’s characteristics and social relationships, drawing on cues like group membership to predict who will share traits, cooperate, or be in conflict.10PubMed Central. The Origins of Social Categorization This is not the same as saying infants hold stereotypes in the adult sense, but the cognitive machinery for sorting people into groups and making assumptions based on group membership is operational from very early in life. Cultural input shapes which categories matter and what expectations attach to them, but the tendency to categorize socially is apparently part of the standard human toolkit.
Cross-cultural research adds an interesting wrinkle. Studies comparing preschool children from Eastern and Western cultures have found that cognitive processing styles differ by culture from a young age, with Eastern children showing more relational attention and Western children showing more object-focused attention.11PubMed Central. Cross-cultural differences in cognitive development: attention to relations and objects These different attentional habits shape what features of a situation children notice and remember, and by extension, what kinds of preconceived notions they develop. A child growing up in a culture that emphasizes relationships between objects will form different default assumptions about how the world works than a child in a culture that emphasizes the objects themselves.
Preconceived Notions in Medicine and Criminal Justice
The real-world consequences of preconceived notions are most visible in high-stakes professional settings where accuracy matters enormously. In medicine, anchoring bias, the tendency to over-rely on the first piece of information encountered, can shape diagnostic decisions in ways physicians may not recognize. A cross-sectional study of patients with congestive heart failure who presented with shortness of breath found that when the documented visit reason mentioned heart failure before the physician saw the patient, doctors were less likely to test for pulmonary embolism, a potentially fatal condition with overlapping symptoms. That initial framing anchored the diagnostic process and was associated with delayed workup and diagnosis.12PubMed Central. Evidence for Anchoring Bias During Physician Decision-Making
Somewhat counterintuitively, specialists may be more vulnerable to this than generalists. An experimental study on anchoring bias in diagnostic decision-making found a significant relationship between the initial information provided and the final diagnosis, and specialists were more prone to anchoring bias than general practitioners.13PubMed. Impact of anchoring bias in medical diagnostic decision-making: an experimental study This may be because specialists have stronger schemas for their domain; their expertise gives them more powerful templates, which usually help but can also lock in an initial impression more firmly.
In criminal justice, the same dynamics play out under the label of “tunnel vision.” Once investigators form a hypothesis about a suspect’s guilt, they tend to favor guilt-confirming investigation strategies over strategies aimed at confirming or excluding alternative scenarios.14Journal of Investigative Psychology and Offender Profiling. Let’s find the evidence: an analogue study of confirmation bias in criminal investigations This is confirmation bias applied to the machinery of justice, and it affects not just police officers but prosecutors, judges, and jury members. A study manipulating tunnel vision and confirmation bias in hypothetical criminal contexts confirmed that these biases operate in ways that selectively filter evidence toward building a case against the initial suspect rather than objectively evaluating all possibilities.15Sage Open. Tunnel Vision and Confirmation Bias Among Police Investigators and Laypeople in Hypothetical Criminal Contexts Wrongful conviction cases have repeatedly revealed this pattern: an early hunch about a suspect hardened into a preconceived notion of guilt, and the investigation filtered all subsequent evidence through that lens.
How Digital Environments Reinforce What You Already Believe
The internet was supposed to expose everyone to a wider range of ideas. In practice, algorithmic recommendation systems often do the opposite, creating what researchers call filter bubbles or echo chambers. These systems track your clicks, searches, and engagement patterns to deliver content that matches your inferred preferences, which means you end up seeing more of what you already agree with and less of what might challenge your views. A systematic review of the filter bubble phenomenon found that while recommendation engines are effective at identifying users’ preferred content, they can also restrict novelty and variety, contributing to information polarization and the solidification of existing beliefs.16WIREs Data Mining and Knowledge Discovery. Filter bubbles in recommender systems: Fact or fallacy—A systematic review
The review also noted that this effect can facilitate group polarization, where people within an echo chamber gradually adopt more extreme versions of their original positions. This is not just about political news feeds. Recommendation algorithms shape what music you hear, what products you consider, what health information you encounter, and what scientific claims you see repeated. Each of these domains involves preconceived notions that get reinforced every time the algorithm serves you confirming content and shields you from disconfirming content. The algorithmic environment doesn’t create preconceived notions from scratch, but it provides an unusually efficient system for hardening the ones you already have.
What Actually Works to Change Preconceived Notions
Given how deeply entrenched preconceived notions can be, the obvious question is whether anything reliably dislodges them. The answer is a qualified yes, but the methods that work are not the ones most people instinctively try.
Simply presenting correct information alongside incorrect information doesn’t work well. What does work better is a technique called refutation text, where the misconception is explicitly stated, directly acknowledged as wrong, and then explained in contrast with the correct information. A meta-analysis of 44 independent comparisons involving nearly 3,900 participants found that refutation text produced a moderate positive effect on learning compared to other instructional approaches, and this effect was consistent across a wide variety of contexts and subject areas.17PubMed Central. Refutation Text Facilitates Learning: a Meta-Analysis of Between-Subjects Experiments The key ingredient seems to be the direct confrontation between the old belief and the new one. When people see the misconception named and then see why it’s wrong, the correction sticks better than when they just encounter the correct information on its own.
Another approach draws on the neurobiology of memory itself. When a stored memory is retrieved, it temporarily becomes malleable, entering what researchers call a reconsolidation window. During this window, the memory can be modified before it is re-stored.18PubMed Central. Impairing existing declarative memory in humans by disrupting reconsolidation Research has shown that a noninvasive retrieval-relearning technique can selectively rewrite existing declarative memories during reconsolidation. This finding has been extended: the reconsolidation window enables memory content to be updated or reshaped in light of new emotional states, contextual cues, or motivational factors.19New Ideas in Psychology. The brain edits the past: Neural systems of memory reconstruction and self-stability In practical terms, this means that the act of recalling a preconceived notion opens a brief window during which new, corrective information can be integrated into the memory trace itself, rather than just competing with it.
For beliefs wrapped up in identity, a different strategy is needed. Self-affirmation, a brief exercise in which people reflect on their core personal values before encountering threatening information, has been shown to reduce defensive processing. In one study, participants who completed a self-affirmation task before reading threatening health information showed increased accessibility of threat-related thoughts, rated the message as higher quality, and formed more adaptive behavioral intentions, compared to those who did not self-affirm.20PubMed. How self-affirmation reduces defensive processing of threatening health information: evidence at the implicit level The mechanism appears to work by separating the person’s sense of self-worth from the specific belief being challenged. When your overall sense of being a good, competent person is secure, letting go of one particular belief feels less like an existential threat.
The Language You Think In Shapes the Notions You Form
One dimension of preconceived notions that is easy to overlook is the role of language itself. The language you speak doesn’t just give you words for your thoughts; it actively shapes the perceptual and conceptual categories you use. Research on neurolinguistic relativity has documented effects of language-specific terminology on perception, grammar-driven differences in how people conceptualize events, and even unconscious modulation of cognitive functions by verbal input.21PubMed Central. Neurolinguistic Relativity: How Language Flexes Human Perception and Cognition Languages that draw sharp terminological distinctions between shades of blue, for example, produce speakers who are measurably faster at distinguishing those shades perceptually. Languages whose grammar requires speakers to specify the direction an action came from produce speakers who are habitually more attentive to spatial orientation.
For preconceived notions, the implication is that your language gives you a set of default categories and framings that you may never question, because they feel like the natural way of carving up the world rather than one cultural option among many. Two people who speak different languages and grew up in different cultural environments will not just hold different specific beliefs; they will tend to notice different features of the same situation, sort the same people into different social categories, and remember different aspects of the same event. Their preconceived notions are shaped not only by what they’ve been told but by the grammatical and lexical structure of the language doing the telling. This makes cross-cultural communication harder than most people assume, because the disagreements are often not about the content of beliefs but about the perceptual categories that precede belief formation entirely.