There’s a new optical illusion in town, and this time it’s a shoe.
Yes, The Shoe has been making the rounds on the internet, ever since someone called Nicole Coulthard published it on a Facebook group called Girlsmouth this week.
She said she saw the shoe as pale pink and white, but her friend said it was pale blue and grey. And thus, here we are.
“Ok girls so my friend has just sent me this asking what colour the shoe is, I would say pale pink and white, but she insists its pale blue and grey,” Coulthard posted on Facebook. “What do you girls see? Please tell me pink and white!”
In the NSN office, the majority of us see the shoe as pink and white, but plenty of people online have been reporting both colors. And several pointed out that it was likely actually pink and white, as Vans – who made the shoe – didn't have a grey and blue version.
But why are we seeing it differently?
First up, let's rule out it being about the screen you're looking at. Different people can look at the same screen and swear they are seeing different things. On the other hand, most people looking at it on different devices may see subtle differences (I see a little more blue/mauve on my phone than on the desktop), but not the drastically different perceptions the “other side” are experiencing.
It's also probably not about your eyes. It's true people have differing ratios of red to green cones. This can cause subtle differences in how we perceive color, particularly under faint light—for example, stars that for some people look red, look white with maybe a pinkish hint to others. However, these physical differences don't produce an effect large enough to explain the dramatically different perceptions here.
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Instead, it seems what we are experiencing is an example of top-down processing, where we see what our brain expects, such as in the case of this optical illusion where the two coloured squares are actually identical.
But it seems that the most popular explanation—at least on Reddit, is that this is an example of a phenomenon known as colour constancy. This ability ensures that the perceived colour of an object remains constant, despite changes in the illumination conditions.
That means the context, or surroundings, in which an object we are looking at appears in, influences our perception of its colour. In the case of this shoe, it is photographed so close up that we don’t actually know its surrounding environment, so our brain starts to make interpretations about the light falling on it. If people envisage that it’s located in, say, a room lit by blueish natural daylight, perhaps near a window, they may see it as white and pink because our brain tries to remove the blue as a possible shadow. Alternatively, some may picture it under artificial lights, like those found in shops, and so they see it as blue, which is indeed the true colour of the shoe.
Still, it's not entirely clear what it is about the colours of the dress and the lighting that cause it to hit a sweet spot that divides the community so drastically