Why First Impressions Are Hard to Change

You meet someone new. In just a few seconds, before they even finish a sentence, your brain has already decided: friendly or cold, smart or not, someone to trust or someone to watch. This is a first impression, and it happens automatically.

The strange part is what happens next. Even if that person later shows you a different side of themselves, your first idea about them often stays. Psychologists call this the "anchoring effect" — your first impression becomes like an anchor, and everything after gets pulled back toward it.

For example, if you meet someone who seems rude on day one, you may notice their rude moments later and forget their kind ones. If you meet someone who seems kind, the opposite happens — you forgive their bad moments more easily.

This is useful to know in real life. In a job interview, a first date, or a new class, the first few minutes matter more than they should. Smiling, being on time, and looking interested in the other person can make a real difference — not because it proves anything, but because it sets the anchor.

Within a tenth of a second of seeing a new face, the human brain has already formed judgments about traits like trustworthiness and competence — long before a single word has been exchanged. This snap judgment is a genuine first impression, and it is remarkably persistent.

The reason lies in something psychologists call the anchoring effect. Once an initial impression forms, it acts as a reference point — an anchor — against which all later information is measured. Behaviour that matches the anchor gets noticed and remembered; behaviour that contradicts it tends to be dismissed as an exception, or explained away entirely. Meet someone who strikes you as arrogant, and a later act of genuine generosity may register as "surprising" rather than as evidence you should update your opinion.

This bias is not simply a personal quirk — it has been demonstrated repeatedly in controlled studies, including ones where participants rated identical resumes more favourably when told the candidate was "warm" beforehand versus "cold," despite the actual content being unchanged. The label alone shifted how every subsequent detail was interpreted.

Awareness of the effect does not eliminate it, but it does offer a practical takeaway: in situations where being judged fairly matters — interviews, first client meetings, new professional relationships — the effort invested in the opening minutes is disproportionately valuable, not because substance doesn't matter, but because it will be filtered through whatever anchor gets set first.

It takes roughly a tenth of a second — less time than a single spoken syllable — for a stranger's face to generate a fully formed judgment about their trustworthiness, competence and likability. What is unsettling is not merely the speed of this evaluation, but its durability: the initial verdict, once formed, proves remarkably resistant to subsequent, often substantial, contradicting evidence.

The mechanism most often cited is anchoring — a cognitive shortcut in which an initial data point becomes the reference frame against which everything subsequent is evaluated, weighted, and often distorted. An impression of warmth primes an observer to interpret ambiguous later behaviour charitably; an impression of coldness does the reverse. Crucially, this is not a passive filter but an active one: disconfirming evidence is frequently reinterpreted to fit the anchor rather than allowed to revise it, a pattern closely related to confirmation bias. The generous act of someone already coded as "difficult" becomes an aberration to be explained away, not data to be integrated.

Experimental psychology has repeatedly demonstrated the effect's force. In one now-classic paradigm, identical biographical material, framed only by a single adjective ("warm" versus "cold") supplied before the fact, produced markedly different evaluations of the same subsequent behaviour — evaluators were, in effect, reading two different people into one identical script. The label did not describe reality; it manufactured the reality subsequently perceived.

The practical and ethical implications extend well beyond dating profiles and small talk. Hiring panels, judicial sentencing, teacher expectations of students — all are documented sites where an early, often superficial signal disproportionately shapes a supposedly objective, evidence-based judgment rendered much later. The uncomfortable conclusion is that objectivity applied after the fact cannot fully undo a verdict formed before the facts were available at all — which is precisely why interventions that intervene before the anchor forms (blind review, structured first-stage evaluation criteria) tend to outperform interventions that merely ask evaluators to "be more careful" once it already has.