What Are Microexpressions?
The split-second expressions that flicker across a face in a fraction of a second, what the research really shows, and why your resting face matters more.
5 min read
A face moving faster than thought
A microexpression is a facial movement so brief it can be over before you consciously register it, typically lasting somewhere between a twentieth and a fifth of a second. The term entered the research literature through the work of Paul Ekman and Wallace Friesen in the 1960s, who noticed these fleeting flickers while reviewing slowed-down film of clinical interviews. Where a normal expression unfolds and lingers, a microexpression appears and vanishes, often before the person making it seems aware it happened at all.
What makes them interesting is the speed itself. The muscles of the face are wired closely to the systems that handle quick reactions, and a movement that fast is hard to stage or suppress on purpose. That is the whole reason the concept caught on: a microexpression is a moment where the face moves before deliberation catches up to it. It is less a hidden message than a piece of timing, a flicker that arrived a beat too early to be edited.
What Ekman actually built
Ekman's larger contribution was not the dramatic idea of a face betraying a secret, but a patient anatomical one. Working with Friesen, he developed the Facial Action Coding System, or FACS, which breaks every visible facial movement into roughly forty-odd component actions, each tied to specific muscles. FACS does not interpret a face or assign it a meaning; it simply names what moved, the way a musician names notes rather than emotions. A coder might record that the outer brow raised, that the lip corners pulled, that one cheek tightened, without claiming to know why.
This distinction matters because microexpressions are often sold as a kind of lie detector, and the science is far more cautious than the marketing. Trained coders can reliably describe what a face did, but reading a single fast movement as proof of a particular feeling, let alone a lie, is exactly the leap the careful research warns against. A flicker of brow tension can come from concentration, glare, a stray thought, or nothing in particular. The honest version of the field describes movements; it does not pretend to narrate the mind behind them.
Why first impressions don't wait for the flicker
There is a quieter finding that tends to matter more in everyday life. Alexander Todorov and his colleagues at Princeton showed that people form confident judgments about a stranger's trustworthiness, competence, and likability from a face in roughly a tenth of a second, and that giving people more time barely changes the verdict, it mostly raises their confidence in it. That is faster than most microexpressions, and it happens whether the face is moving or perfectly still. The first read is built largely from the structure and the resting set of a face, not from a fleeting twitch.
Layered on top of that is the halo effect, first described by Edward Thorndike, the well-documented tendency to let one salient impression bleed into unrelated judgments, so a face read as warm gets quietly credited with honesty and competence it has not earned. Put the two together and the practical truth emerges: long before anyone catches a microexpression, your steady, default expression, the face you wear when you think no one is reading it, has already done most of the talking.
What this means for how you come across
Aura Mirror is built around that second, slower truth rather than the cinematic first one. It does not chase microexpressions, claim to detect lies, or read your health, your mood, or your future, and it would be dishonest to suggest a photograph could. What it can do is the thing the Todorov research points to: describe how your resting face is likely to land on a stranger in that first tenth of a second, with visible evidence drawn from the photo itself rather than guesswork about what you are secretly feeling.
Think of it as a coding pass, in the FACS spirit, on your projection rather than your psychology. The set of your brow, the openness of your eyes, the default angle of your mouth, these are the features that shape a first impression long before any flicker arrives, and unlike a microexpression they hold still long enough to actually look at. Knowing how that steady face reads is far more useful, and far more honest, than any promise to catch the truth in a twentieth of a second.