10 years later, 'the dress' still divides us. But we understand a lot more about why.

In late February 2015, the internet seemed to be a simpler place. Tumblr was still popular, Twitter was still Twitter and "going viral" was something of a more ubiquitous experience. And nothing that year went more viral than the infamous, argument-starting, internet-dividing, ever-enduring mystery of "the dress."

It began with a wedding. As Grace Bleasdale and Keir Johnston prepared for their Scotland nuptials, the mother-of-the-bride, Cecilia Bleasdale, texted her daughter an image of the dress, saying she planned on wearing it at the festivities.

When Grace and her mother couldn't agree on the color of the dress, Grade posted it to Facebook and a friend later shared it to the then-popular blogging site Tumblr, asking viewers to weigh in: do you see a blue and black dress or a white and gold one?

The debate then was made into a poll posted by BuzzFeed Community Manager Cates Holderness, where more than 16 million people saw it. Big names like Ellen DeGeneres began weighing in. Then, it absolutely blew up.

A decade later, an argument is still likely to ensue if you ask the now-infamous question: blue and black or white and gold? In the USA TODAY newsroom just this week, it certainly did.

But the dress was more than just a viral phenomenon − it was a boon to science. And if you participated via a tweet, a click on a poll or an argument at the dinner table, you likely contributed in some small way to the advancement of our understanding of color perception as we know it.

Sorry white and gold people, 'the dress' is actually blue and black

There is a definitive answer to the color question. The retailer of the dress, Roman Originals, confirmed that the dress is blue and black in reality, tweeting on Feb. 27, 2015, "We can confirm #TheDress is blue and black! We should know!"

The brand, which struggled to keep the dress in stock after it went viral, later created a special, one-off white and gold version to sell at a charity auction benefiting Comic Relief, a U.K. organization that combats poverty.

Now called just Roman, the clothing retailer hasn't forgotten its claim to fame. Its website made an entire webpage for the 10th anniversary, which lists the official date of virality as Feb. 26, 2015. According to the brand, #dressgate prompted 7.6 million tweets, some of which were from the likes of celebs like Taylor Swift and Kim Kardashian.

The brand also said that netizens viewed the dress 73 million times across all social media platforms, resulting in the site selling out in just 34 minutes. Perhaps surprisingly, 70% of people who posted about the dress initially saw it as gold and white, not its true blue and black, according to Roman.

"A decade ago, 'The Dress' broke the internet, sparked debates at dinner tables, and changed the way we see colour—literally!" Michele Bastock, Roman Brand Director said in a statement to USA TODAY. "As the original retailers of the viral sensation, we’re still in awe of how one dress captivated the world. Whether you saw blue and black or white and gold, one thing is certain: #TheDress remains an icon. Here’s to 10 years of optical illusions, internet magic, and unforgettable moments!"

From internet phenomena to scientific boon

If anyone tries to tell you that keeping up with Internet trends is a waste of time, tell them they may just be miss witnessing the next scientific breakthrough.

Neuroscientist Bevil Conway, senior investigator at the National Eye Institute, part of the U.S. National Institute of Health, was one of the first members of the scientific community to offer some insight into the "why" behind the illusion a decade ago. In the interim, he said, scientists have figured out a lot about how our brains perceive color − and the dress was central to that development.

"The dress has been enormously instructive for science, the scientific understanding of how color works," he told USA TODAY. "It really did emphatically teach us that the brain contributes a lot of the heavy lifting to interpreting the light that enters the eye and telling us what color it is (we're seeing)."

When the dress first went viral, Conway was inundated with media requests after providing an interview to Wired. It was when speaking with Wired's Adam Rogers that he first theorized that the phenomena didn't have to do with the eyes, but the brain.

"At first, it was hotly contested and debated," he said.

Since then, however, a breadth of scientific evidence has cropped up around the subject. Papers have been published and the scientific community now largely agrees on an explanation.

"One consensus is that how you interpret what you see is dependent on assumptions that your brain makes automatically about the color of the light," he said. "Now that is (the) consensus. People believe that is the explanation for the dress − how the brain makes assumptions about the lighting. It's not about rods and cones, it's not about whether or not you're colorblind, it's not about anything going on in the eyeball. It's the brain."

As you move through the world, the source of light entering your eyes varies in color, like viewing a cool blue sky or warm direct sunlight, he explained. Your brain does color correction to make sure that what you see is stable in color, even when you're looking at the world under different types of light.

When your brain doesn't have all the information it needs, it fills in the blanks.

"This particular image (of the dress) doesn't have enough cues in the image itself to tell you what the color of the light is, so you have to rely on assumptions that your brain is making," Conway said. "Some people assume that the color is warm, so they subtract some orange from the dress and see blue and black, but some people assume the light is cool colored, more blue sky, so they subtract the blue color."

There isn't enough evidence to tell us why exactly some brains are more likely to make one assumption over the other, though Conway has theorized it could be linked to how much waking time you spend under light, like the blue sky versus incandescent illumination.

The script has flipped on what colors most people see

Information and exposure also play a role in what you see and explain why over time, more people have come to see the dress one way over the other.

When the dress first came out, the split was about 50/50 for blue and black versus white and gold, said Conway. Now, 10 years later, the fact that the garment is black and blue in reality has become common knowledge, effectively changing how the majority of people perceive the once-divisive image.

"Most people now know that the actual dress is blue and black, so that knowledge has changed how you see the image," said Conway. "So in real-time, we have experienced in our lifetimes, the impact of knowledge on color perception."

A viral moment helped answer an age-old question

If you see the dress one way, that doesn't mean you can't change your mind, explained Conway. Many people can "flip" how they perceive the dress, allowing them to see either set of colors. This is because the image is bistable, similar to the famous Rubin vase illusion.

Known more colloquially as the vase-face optical illusion, Rubin's vase can be seen as the black profiles of two faces looking at each other or as a white vase, but not both at the same time. Sometimes, the colors are switched, but the premise is the same: you either see faces or a vase.

Depending on what part of the image they focus on, most people can flip between seeing one or the other. Other famous examples of this are the duck-rabbit illusion (sometimes called the rabbit-duck or Jastrow duck-rabbit) or necker cub. Like with the dress, when this and similar illusions first came out, it was believed each person's perception was fixed so they could only see it one way or the other.

"It was discovered that with practice and encouragement and persistent viewing, almost everyone can flip, we now have seen," said Conway. "We have data showing that the proportion of people that can flip has increased over time."

The dress has been so consequential to our understanding of the science of color perception that it has added to the body of evidence answering a question dating all the way back to the great philosopher Immanuel Kant, who in the 18th century theorized humans can never really know if they see color the same way, as they can't literally see through someone else's eyes.

https://www.tumblr.com/swiked/112164479015/can-we-have-more-pictures-of-the-dress-please-we

As it turns out, we more-or-less know that answer even without being able to crawl into each other's heads, largely because we have developed a language that is advanced and instructive enough for us to effectively communicate our experiences with each other.

"The dress is the most powerful example that we all do see color very similarly, because when it fails − when we don't see color similarly − it creates an all-mighty viral color fiasco like this," Conway said. "Under most circumstances, we're pretty good at seeing it the same way."

This article originally appeared on USA TODAY: 'The dress' went viral 10 years ago and taught us the science of color