What color is this dress?

Chances are, at some point in the day, you will still hear the following question: “What color is this dress? The curiosity is due to a simple photo of a woman wearing a striped dress. It's two colors. You must already be thinking: Okay, so what? Come on… there's no way to understand without doing a simple test first… Call someone, anyone who's around and ask what colors he sees in the dress? You will probably be surprised by the answer…

Read also bonito no espelho e feio na foto, Face shape changes in photos e artificial intelligence.

The "incident" began when a student began to notice that he could not agree with his classmates about the color of a dress worn in a photo after he had shared it.

When questioning about the color of the dress found in the photo, he noticed that several people were always divided between two answers: some say it is blue and black, others guarantee that it is gold and white (The photo below shows both the color you are seeing, like the one your colleague guarantees he sees).

The first explanation to appear on the network pointed to the fault of the monitor in which the photo was seen… wrong! (Anyone who doubts, can print the photo on a sheet of paper, to verify that the color of the dress continues to cause divergence). Color blindness, some say…. Neither…

It is already known, according to the photographer, that the true color is blue and black. Now, why are people guaranteeing it's gold and white?

But why does this happen?

The site BrasilPost explains: the irreconcilable differences of opinion between pro-blue and pro-white are due to physiological issues. Depending on the context, our brain may try to “interpret” colors on its own, as this article published in the journal explains. Cell.

We evolved to see in sunlight, which changes color depending on the time of day. So we're used to try to compensate for possible distortions that the luminosity causes in the color of the objects. "People can discount the blue side, which in this case makes them end up seeing white and gold, or discount the golden side, which makes them see blue and black," neuroscientist Bevil Conway told Wired.

isso reports not only of aspects of the environment but also of the particular constitution of each human eye. Age can also influence. In general, according to Time, the older the observer, the greater the propensity to see white and gold. But that does not mean that the color of the dress is a matter of point of view.

But, in more technical terms, isolating each shade of the piece and checking the RGB scale, it is undeniable: the dress is blue and black.

According to another explanation that is being passed around on the internet, in the back of the eyes are the retinas, structures that allow you to detect color. Color perception is associated with the activity of certain cell types called cones. The rods are responsible for the perception of shadows, given by the association of black, white and gray. You cones will only activate in the presence of sufficient light. There are three types of them, small, medium and large, sensitive to blue, green and red.

To understand the reason for the divergent perceptions of color related to the dress in the image, it is first of all necessary to understand the neurophysiological color systems.

Additive System:

When we talk about color, we are actually talking about light, because without light there would not be what we call “colors”. In nature we find two chromatic systems: the additive system and subtractive system. O additive system is the one formed by the three primary colors of light (blue-violet, red and green), decomposed from the white sunlight that is the natural source of light on planet earth. Electric lamps, candles and other lighting devices provide us with synthetic lighting. it's called additive because the addition of the three primary colors results in the perception of white light.

Subtractive System:

All objects in the world have color. This color is formed by the natural or synthetic elements found in its outer layer. Pigments can also be natural or synthetic. These pigments in contact with light-colors will absorb certain bands of chromatic wave and reflect others, which will be captured by the human eye. O subtractive system takes this name in view that the mixture of its primary colors tend to black, that is, absence of light. The primary colors of subtractive system are the cyan, magenta and yellow.

Summing up…

If you are seeing the blue and black dress: Your retinal cones are quite active, and this results in your eyes doing the subtractive blending.

If you are seeing the white and gold dress: The eyes don't work well in low light and the rods in your retina detect white. Less sensitive to light, your eyes create the mixture of additives, green and red, to make gold.

On the other hand, if you see the dress sometimes white and gold, sometimes blue and black, or a combination of the two, your eyes are “medium level” and can change due to the luminosity of the environment in which they are or due to the way they are located. how tilted your computer, phone or tablet screen is. This type of divergent perception is the same type that occurs in many sensory manipulations produced by optical illusions.

This was the most plausible explanation we found to explain the phenomenon.

Sources: Unicamp, Buzzfeed, My brain, BrasilPost.