Research using facial-judgment tasks has found that people form trait impressions — trustworthiness, competence, likability — from a face in as little as 100 milliseconds, well before conscious, deliberate evaluation kicks in.
Why So Fast
These snap judgments appear to be an evolutionary shortcut for assessing threat versus safety quickly, a mechanism that predates language and deliberate reasoning.
The Anchoring Problem
Once formed, a first impression acts like a lens: subsequent, contradicting information tends to get reinterpreted to fit the initial judgment rather than overriding it, which is part of why first impressions are so persistent.
What This Means Practically
Because snap judgments are hard to reverse, the highest-leverage moment in a new interaction is often the first few seconds, not later attempts at correction.
