What the eye decides

In a home goods shop in Doha, two water filter jugs sit side by side on the shelf.

One is tall and glossy, with a blue light in the lid and a box covered in close-up photographs of clear water. The other is plain and squat, in a box that mostly carries text. The plain one filters better and its cartridges last longer. A shopper who reads the small print can find this out. Most shoppers take the glossy one home.

That is not stupidity. It is how we are built. Seeing takes up so much of the brain that it tends to overrule the quieter evidence. What we can see, we believe. What we cannot see barely registers.

Sometimes that works for us. A heavy box, careful wrapping, a lid that lights up can make the water taste better to the person drinking it, and that pleasure is real even if the cartridge inside is ordinary.

But it works against us whenever the thing that matters is invisible. What a filter removes cannot be seen. Neither can how a cartridge wears out over six months, how a cheap seam will open after the tenth wash, or the damage done slowly by something nobody tested for. Those things only show themselves later, long after the choice was made on what was visible on the day.

So the seller who puts effort into what cannot be seen has a problem that better work alone does not solve. Somehow the invisible has to be made to show up.

And the rest of us have a harder habit to build. When the evidence in front of us and the facts we have learned point different ways, we tend to side with our eyes, and very often that is the wrong side to take.