How long does a first impression take? About a tenth of a second.

About one hundred milliseconds. That's how long your brain needs to decide whether a stranger looks trustworthy, competent, likeable or threatening. It's roughly the time it takes to blink. And here's the part most people don't know: giving your brain longer doesn't change the answer. It only makes you more confident that the answer was right.

That finding comes from a 2006 study by Janine Willis and Alexander Todorov at Princeton, and it's worth understanding properly, because it explains a lot about how people treat each other and how you get treated in return.

Willis and Todorov showed people photographs of unfamiliar faces and asked for a judgement on one trait: is this person trustworthy, competent, likeable, aggressive, attractive. The catch was exposure time. Some faces flashed up for a tenth of a second. Some for half a second. Some for a full second. Nobody struggled to answer, even at the shortest exposure.

Then they compared those snap answers against another group who had been allowed to look at the same faces for as long as they wanted before deciding. The two sets of answers lined up closely. A tenth of a second produced roughly the same verdict as unlimited time. Trustworthiness was the trait people settled on fastest of all.

This is the bit worth sitting with. When people got longer to look, they didn't revise their first read. What went up was confidence. Given more time, participants felt surer about the same call they'd already made in a blink.

So the snap judgement isn't a rough draft that careful thought comes along and corrects. Mostly, careful thought just signs off on it. You look longer, you feel more certain, and the certainty gets mistaken for accuracy.

Because it has to. Sorting is the brain's oldest job: safe or not, friend or not, worth attention or not. That sorting runs faster than the part of you that watches yourself think. By the time you feel like you're forming an impression, the impression is already formed.

Psychologists sometimes call this thin slicing, and it's a form of compression. The brain takes a huge amount of visual information and squashes it into a usable read in the time it takes light to hit the back of your eye. It is not a character flaw. It is standard equipment, running in every head, including yours.

Which is uncomfortable and freeing at the same time. Every room you've ever walked into sorted you before you'd finished saying hello. You did the same to everyone in it. Nobody opted in. Nobody can opt out.

A first impression is information about the sorting machine, not about the person being sorted. A tenth of a second can read a face. It cannot read a history, a bad week, a good heart, or a nervous morning. The first impression is real, and it is also thin. Both of those are true at once.

The problem isn't that the read happens. It's what happens next. A first impression can be checked against more evidence. Most never are. Confidence arrives early and does the rest, and the person on the receiving end spends the rest of the conversation, or the job interview, or the friendship that never started, working against a call that was made before they spoke.

Knowing this doesn't switch it off. Nothing does. But it changes what the first read is allowed to be. It gets to go first. It doesn't get to be final.

Fair question. Not Your Label is a small made-to-order clothing brand based in Sydney, and the name is the short version of the answer. The longer version is on the About page. The clothes don't require you to have read any of this.

A snap judgement is a label your brain wrote in a hurry. (Drafts, not verdicts, ya know?)

How long does it take to form a first impression? About 100 milliseconds, based on Willis and Todorov's 2006 study. Judgements made in a tenth of a second matched judgements made with unlimited time.

Does taking more time make first impressions more accurate? Not in the study. Longer exposure didn't change the judgement, it only increased how confident people felt about it.

Which trait do people judge fastest? Trustworthiness. It was the judgement people settled on most quickly and consistently at the shortest exposure.

Can you stop making snap judgements? No. It's automatic. The first read always goes first. It doesn't have to be final.