It’s the social media phenomenon that pitted friend against friend, family against family, and mildly tolerated co-workers against one another. I’m referring, of course, to #TheDress.

For several days starting in late February, a fierce debate over the true colors of a horizontally stripped dress whose picture was first displayed on a Tumblr post spilled off the Internet and onto the hard streets of real life. For many, the dress clearly appeared to be blue and black, yet for others, it was obviously white and gold. Twitter users, a sea of bloggers, celebrities, and even scientists weighed in on #TheDress, with more than 28 million views amassed for a poll on BuzzFeed about its true identity. Eventually the person who originally posted the snapshot, Caitlin O’Neill, who herself was perplexed and had only tried to enlist some help from her Tumblr followers, stepped forward. The dress, as verified by the company which produced it, was blue and black (duh).

And so the fervor eventually died out, though not without plenty of companies and even non-profit organizations cashing in the hype. But left unanswered was the burning question. Why did so many people see different colors of the same dress? Plenty of academics and other learned experts offered their own educated opinions, generally placing the blame on the peculiar lighting of the original photograph. But now, two months later, a study published today in Current Biology claims to have solved the mystery. Turns out that it’s just not about the colors we saw in the dress, but about the colors we didn’t, namely red and green.

The researchers studied two groups of participants who were divided on the dress, attempting to decipher how they perceived color in general. Surprisingly, they found that everyone had similar color perceptions. But as guessed by some, it was in how they perceived the lighting surrounding the dress that influenced their version. "The perceived hue in one of the groups of observers is related to the fact that a white dress was exposed to cool bluish light," study author Dr. Karl Gegenfurtner said in a press release. "Just as well it could be a blue dress which was overexposed by warm light." As daylight runs the gamut from light blue to yellow, it seems that the true difference of opinion was in what time we thought the photograph was taken. The authors note that, far from two strictly defined camps, there was a wide continuum of dress perception; with two additional studies published in Current Biology today finding that they even could tweak people’s opinions by changing their perception of what type of light was surrounding the dress.

But the mass confusion likely never would have happened had there been a splash of red or green somewhere in the photo. As Gegenfurtner explains, these colors are unconsciously used by people to establish how bright an area is, with neither color naturally appearing in daylight. "This would not have happened with a red dress," Gegenfurtner said.

So for those of us who are still nursing rivalries over #TheDress, perhaps these studies can finally begin the healing process.

Source: Gegenfurtner K, Bloj M, Toscani. The many colours of ‘the dress’. Current Biology. 2015.