A look that lasts less than a second

In an eyewear shop in Abu Dhabi, a customer asks to see the cheaper frames. The assistant says of course, walks her to the right shelf, and is perfectly polite. But for an instant, before the smile, something crosses his face. Not quite boredom. Not quite disdain. It is gone almost before it arrives.

She buys nothing and cannot say why.

Faces send signals faster than their owners can manage them. A flicker at the corner of the mouth, a brief tightening around the eyes, and the other person has already read it. We are built to catch these things, because for most of human history knowing in an instant whether someone meant us well was useful. Usually neither side notices the exchange. The customer simply feels unwelcome. The assistant simply wonders why his side of the shop is slow.

Some people do the opposite without trying. A quick warmth when they look up, a flash of real interest when someone asks a question, and people call them easy to talk to without knowing what they are describing.

The flickers are hard to control. They come from somewhere beneath good manners, often from tiredness or worry rather than any real verdict on the person in front of us. The assistant may not feel contempt at all; he may have been thinking about his rent.

But the response is real either way. Customers react to what they saw, not to what was meant. Knowing that the signal exists, and what tends to set it off, will not make it disappear. It does explain why some days go the way they go, and it is where changing them begins.