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Scientists have finally figured out why people saw “The Dress” in different colours

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Matt Tate
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Remember The Dress? 

Of course you remember The Dress, because you use the internet and back in 2015 it was quite literally all anybody on the internet cared about. Websites crashed, families were divided and strangers fought each other on the streets, all because a single picture of a dress.

Was it blue and black, or white and gold? The definitive answer was the former, but that didn’t stop thousands of people furiously pounding their keyboards to tell you how wrong you were, you idiot. 

The Dress:

Guess who's back, back again

As a society, as a people, we moved on to more unifying memes like Harambe and Joe Biden. But as far as science is concerned, The Dress remains a marvel. 

Pascal Wallisch, a clinical assistant professor of psychology at New York University, thinks that now, more than two years after the infamous picture was first uploaded to Tumblr, we have a much better understanding about why people saw it differently. 

Writing for Slate, he explained that a major factor was the uncertainty surrounding the source of lighting in the picture. Essentially, the way our brains perceive colour is directly linked to our perception of lighting. Because it’s not clear whether the photo of the dress was taken inside or outside, we’re unable to accurately assess the lighting. Is it artificial or natural? This is key.

Wallisch writes: 

The brain cannot be accused of epistemic modesty. It is well-known that in situations like this—where it faces profound uncertainty—it confidently fills in the gaps in knowledge by making assumptions. Usually, its assumptions are based on what it has most frequently encountered in the past. For instance, if the sensory information is more uncertain, observers will estimate object speeds to be slower than they actually are, presumably because slow objects are much more common in the environment than fast ones. (Indeed, most objects in any given field of view don’t move at all.) Color and lighting are no exception.

The scientist’s research found that those who assumed the dress was in shadow were more likely to see it in white and gold, as you were if you thought it was illuminated by natural light.

Why? Because the sky is blue, daylight also overrepresents short wavelengths, compared with relatively long-wavelength artificial (until recently, usually incandescent) light. Just as mentally subtracting blue light leaves the image looking more yellow, mentally subtracting yellow light from an image leaves an image looking more blue, which is what I found empirically.

There’s more. Wallisch found that the colour you see could even tie in to your bedtime. He outlined that early-risers (“larks”) go to bed at a decent time and are exposed to more natural light than those who sleep in and go to bed much later (“owls”). Stressing that the recorded effect was ‘subtle but statistically reliable’, he went on to explain that day-loving larks were more likely to see a white and gold dress, while owls – with their Netflix binges and midnight feasts – might assume that the lighting was artificial. This obviously could never be a statement applicable to everyone, but it did stack up. 

The Slate article goes into much, much, more detail, so we recommend a lunch-time deep dive to anyone interested. 

And sorry for making you think about that dress again. At least we all know for sure that it’s blue and black. Probably. 

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Matt Tate

Matt Tate is a freelance journalist

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