a students' magazine

White and gold or black and blue?

Hi guys! 🙂 If I had seen THAT dress in a shop window, I wouldn’t even have given it a second glance. Now it’s everywhere and I can’t get it out of my head! The prime culprit is my brother, who showed me the photo saying that it was black and blue, but all I could see was white and gold. Since I didn’t want to admit defeat I looked for a scientific explanation that could prove me right 😉

So I discovered that it all comes down to colour perception. First of all, try watching this video that will explain what colour the dress actually is.

In our everyday lives, there are many changes in the colour of the light illuminating our surroundings. The light that an object reflects to the eye is a combination of both the colour of the object itself and the spectrum of the light source, which may vary.

However, when the brain interprets these wavelengths as colour, it is also working out how illuminated the colour is by the light around it and subtracting that from the ‘real’ colour.

The brain recognises the same object as having the same colour regardless of the time of the day – and does it quite well. This phenomenon, known as colour constancy, ensures that the perceived colour of an object remains constant, despite changes in the illumination conditions.

For example, a white surface illuminated with a red light will appear reddish. The same white surface illuminated with a blue light will look bluish. To recognise in both cases the surface as white, we must consider the colour of the light source. So it should not surprise us that the colour perception can be influenced by the context.

To understand what happens to our colour perception, we need to know that our brain uses two different ways to perceive things, a top-down process and a bottom-up process. In this case, perception is a process that depends on top-down processing. This process consists in making the best guess or a hypothesis about something relying on your past experiences and prior knowledge. When we see something, our brain creates a perceptual hypothesis about the stimulus, based on its memory and past experience that may be related to it. When it comes to colour and visual illusions, the brain may create incorrect hypotheses, leading to several errors of perception.

Those who interpret the dress as illuminated by a blue light think that the white dress looks blue because of the light and the gold colour doesn’t change, so they will see a white and gold dress. Those who see it black and blue interpret the dress in an artificial light setting, so the brain sees the gold as a reflection of the black and believes that the blue has been unaffected. It is remarkable that the image itself allows both interpretations: the lighting seems bluish at the top, but yellowish at the bottom. So a blue and black dress illuminated by a white light may be indistinguishable from a white and gold one covered by a bluish shadow!

So, who’s right and who’s wrong?

Well, it’s with great sadness that I announce that the real dress is black and blue! That means that I was wrong and my brother was right 😦

See you next time 🙂

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