In the last 12 hours, the internet has gone wild over "The Dress" – a picture of a dress posted by the user swikes on Tumblr, together with a caption saying: "Guys please help me - is this dress white and gold, or blue and black? Me and my friends can't agree and we are freaking the f*** out."
Some internet users see the bodycon dress as blue with black lace on it, while other users see a white bodycon dress topped with gold lace.
What netizens are experiencing is a kind of brain trickery akin to colour blindness.
According to scientists interviewed by Wired, it's all about colour balancing and the way that the brain interprets light entering the eye.
This process of how the brain interprets colours is the reason why some people are colour blind and are unable to see the colours red, green and blue, which means that they see the world in totally muted colours, and frequently mix up colours as they can't see either red and green, or blue and yellow.
Our visual systems tend to vary from person to person, but what we see is determined by how the brain figures out the colour of the object in front of us, as well as the colour of the light bouncing off the object into our eyes.
In order to show us colours, the brain makes a calculation and decides to filter out the colour of the light, whatever that might be, so in the case of The Dress – the brain in some people discounts the colour gold, so they see a blue and black dress, while in others, the brain discounts the colour blue, so they see a gold and white dress.
Tricking the brain
A US-based company called EnChroma has come up with sunglasses that are able to similarly trick the brain into showing people with deficient colour vision what the world really looks like.
Colour blindness is a rare genetic defect that affects approximately one in 12 men and one in 200 women in the world. In the UK, there are approximately 2.7 million people with deficient colour vision, most of whom are male, according to the Colour Blindness Awareness Association.
The EnChroma CX glasses contain lenses that work by removing the wavelengths of light between primary colours using a series of "precise cutouts". Each lens is made from 100 layers of dielectric material, with each individual layer measuring just a few nanometres in thickness.
When the layers are combined in just the right way, they remove the wavelengths of light between primary colours, thus causing the colour signal being sent to the brain to be much stronger, and so the brain doesn't try to discount the colours that the person sees.
Thus, colour blind people are able to see much brighter, more vibrant colours and are able to differentiate objects from a background.
The EnChroma CX colour blindness correcting sunglasses are not cheap, however, and retail from £349.95 per pair, but the firm says that they enable people with deficient colour vision to see 10,000 colours.
Whether or not these sunglasses can solve the great Dress debate is another matter...