The Psychology of First Impressions — and Why You Rarely Recover From a Bad One

You’ve Been Judged (in Less Than a Second) Before you’ve spoken a word, shaken a hand, or opened your laptop in a meeting, people have already decided who you are. Research shows that humans form first impressions in as little as 100 milliseconds—roughly the blink of an eye. A 2006 study from Princeton University found that participants could reliably judge traits like trustworthiness and competence from brief facial glimpses, often matching longer evaluations. Our brains are wired for snap assessments because, evolutionarily, quick judgments once meant survival. But in modern life, that instinct can be brutally misleading.

The Science of Snap Judgments

At the core of first impressions lies the amygdala, the brain’s emotional alarm system. It rapidly processes faces and body language, categorizing them as safe or threatening before the rational brain (the prefrontal cortex) even joins the conversation. This process happens automatically, using thin slicing—a concept coined by psychologist Nalini Ambady to describe how we make broad conclusions from limited information. In her studies, students watching just six seconds of a teacher’s lecture rated effectiveness almost identically to students who watched the full class. The takeaway? Our intuition is fast, but not always accurate.

Why First Impressions Stick

Once formed, impressions are notoriously hard to change because of confirmation bias—the tendency to interpret new information in ways that reinforce our initial beliefs. If someone seems unfriendly at first, we unconsciously notice every behavior that fits that label and ignore what contradicts it. Neuroscientific evidence shows that the brain stores early judgments in the ventromedial prefrontal cortex, an area linked to emotional memory, making them resistant to updates even after contradictory experiences. In short: the first version of you people meet tends to be the one that stays in their minds.

Can You Undo a Bad First Impression?

It’s possible, but it takes consistent disconfirmation. Research from Columbia University suggests that meaningful attitude change requires repeated, emotionally positive interactions that directly counter the original impression. This process, called recalibration, essentially forces the brain to overwrite its initial emotional data. It’s why one great conversation or act of kindness won’t instantly erase a poor first meeting—it takes a pattern of new evidence to shift perception.