Research on first impressions has found that people form judgments about strangers — including perceived trustworthiness, competence, and likability — within a fraction of a second of seeing a face, often well before any actual interaction takes place. What’s more striking is how durable these snap judgments tend to be, even when later evidence doesn’t fully support them.
How fast is fast
Research by psychologist Alexander Todorov and colleagues found that judgments of traits like trustworthiness and competence from a facial photograph formed within roughly one-tenth of a second, and that giving participants more time to look at the same face did little to change their initial assessment, suggesting the first impression largely sets the frame rather than being gradually refined with additional information.
Why first impressions are so sticky
Part of the reason first impressions persist is a well-documented cognitive pattern called confirmation bias: once an initial judgment forms, people tend to notice and remember information that supports it, while discounting or simply failing to register information that contradicts it. If you decide in the first moment that someone seems unfriendly, you’re more likely to interpret their subsequent neutral behavior as confirming that impression, rather than questioning the original judgment.
The halo effect
A closely related pattern is the halo effect, where a single positive trait, often something as superficial as physical attractiveness or a confident speaking style, leads to generalized, often unwarranted assumptions about unrelated positive traits, such as intelligence or trustworthiness. This effect has been documented across a wide range of contexts, including hiring decisions and courtroom outcomes, and operates largely outside conscious awareness, meaning even people who consciously reject the idea that appearance should matter are still measurably influenced by it.
What actually shapes that first split-second
Research on which specific facial and behavioral cues drive snap trustworthiness judgments has found that certain features consistently correlate with judgments of trustworthiness independent of a person’s actual character — including aspects of facial structure a person has no control over. This raises a genuinely important caution: snap judgments, however automatic and confident-feeling, are not reliable indicators of a stranger’s actual character, since they’re often responding to superficial cues entirely disconnected from the traits being judged.
Can first impressions be revised
While first impressions are sticky, they aren’t entirely fixed. Research suggests that sustained, direct contradictory evidence, particularly through repeated positive interaction, can gradually shift an initial impression, though this typically requires considerably more effort and evidence than the near-instant formation of the original judgment required. This asymmetry — fast to form, slow to revise — is itself a consistent and well-documented feature of how impression formation works.
What this means in practice
- Be aware that your own snap judgments of new people are often driven by superficial cues rather than genuine character, and hold them loosely rather than treating them as settled fact.
- In situations where first impressions genuinely matter, such as interviews, remember the asymmetry runs both ways — a strong first moment carries disproportionate weight.
- When you catch yourself confirming an early judgment, deliberately look for genuine disconfirming evidence rather than passively accepting whatever fits the existing impression.
Understanding how quickly, and how imperfectly, these judgments form is less about distrusting your own instincts entirely, and more about recognizing when a confident-feeling snap judgment deserves a second, more deliberate look.
First impressions across cultures
Cross-cultural research on first impressions has found both notable consistency and meaningful variation: judgments of certain basic traits from facial expression show reasonable agreement across different cultural groups, while the specific weight given to traits like confidence versus warmth in forming an overall positive impression can differ depending on cultural context and what a given culture tends to value in social interaction. This suggests the speed of first-impression formation may be a fairly universal feature of human cognition, while the specific content of what counts as a favorable impression is shaped considerably by cultural learning.