Appearances can be deceiving: the psychology of why we misjudge people in a tenth of a second

September 3, 2026 - 16:56

The human brain forms a judgment about a stranger's character in about one-tenth of a second. That snap decision feels like a reliable gut instinct, but psychologists say it is actually a fast, automatic process built on outdated evolutionary rules, not on any real evidence about who that person is. The result is a persistent gap between what we think we see and what is actually there, and that gap quietly influences major life outcomes, from who gets hired to who gets a second date.

Researchers point out that this rapid assessment likely served an ancient purpose: quickly deciding friend or foe. In a modern world, however, that same shortcut leads us to overtrust a confident face or dismiss someone who is simply anxious. The problem is that these judgments feel certain. The brain does not flag them as guesses. It presents them as facts, which makes them hard to override even when we learn more.

The consequences are measurable. Studies show that people with certain facial features, like a wider jaw or a more expressive brow, are consistently rated as more competent or trustworthy, regardless of their actual behavior. In job interviews, a candidate who makes strong eye contact and speaks in a steady tone can be perceived as more capable, even if another candidate has a better track record. In dating, a fleeting expression of discomfort can be misread as coldness or disinterest.

Psychologists argue that the real danger is not the initial impression itself, but our unwillingness to revise it. Once the brain locks in a label, it looks for evidence to confirm it and ignores information that contradicts it. This confirmation bias turns a tenth-of-a-second guess into a lasting belief. The takeaway is not that we should stop trusting our instincts entirely, but that we should treat them with more humility. A first impression is a starting point, not a verdict. The most accurate reads on people come from time, conversation, and the willingness to admit that our first glance was probably incomplete.