Long ago, way back in 2015, “the dress” became a polarizing viral behemoth. Like the Capulets and Montagues, the masses were split into two camps — those who looked at the dress and saw blue and black and the others who saw gold and white. They could not see eye to eye and frantically sought to understand why they saw one set of colors while others did not. Even the notoriously nonpartisan Taylor Swift broke her media silence to enter into the fray, siding with team #blackandblue.

Now, scientists say there’s a definitive explanation for the discrepancy, despite the fact that the dress is confirmed to be black and blue (nice work, Taylor).

In a new paper published in the Journal of Vision, New York University neuroscientist Pascal Wallisch, Ph.D., explains that the way a person perceives the color of the dress comes down to how they assume it is illuminated. He discovered that if people assumed the dress was lit by artificial light, they tended to think it was black and blue. However, if people believed the dress was just shadowed in natural light, they thought it was gold and white.

“Shadows are blue, so we mentally subtract the blue light in order to view the image, which then appears in bright colors — gold and white,” Wallisch explained in a statement. “However, artificial light tends to be yellowish, so if we see it brightened in this fashion, we factor out this color, leaving us with a dress that we see as a black and blue.”

Wallisch came to this conclusion after surveying 13,000 study participants who claimed to have previously seen a photo of the infamous dress about how they thought it was illuminated. Wallisch found that people who thought the dress was in a shadow were more likely to think it was gold and white.

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The next part of the study was figuring out exactly why that correlation occurred. Participants were asked a variety questions about their demographic factors, such as their age and gender, and whether or not they were early risers or night owls. Interestingly, Wallisch discovered that people who preferred going to bed early and felt best in the mornings were also more likely to think the dress was white and gold. He also found that people over the age of 65 were more likely to see black and blue, though the morning/night person divide was the more influential factor.

Wallisch thinks morning people are more likely to see white and gold because they have the assumption bias that the world is illuminated by the sun (which would cause a shadow) instead of artificial lighting. This finding underlies the fact that we can’t always trust what we see; scientists have learned that when we visually perceive something, our brains fill in any gaps of information with what it already assumes is true. In the case of the dress, perceptions of illumination change our assumptions about color constancy, which can result in widely different opinions about how something can look.

The dress is blue and black, but if you presumed it’s gold and white you shouldn’t necessarily think that’s a bad thing: Take solace in the fact that while others assume the world is lit by artificial lighting, you still think of it as illuminated by the sun.

Photos via Giphy