The 21 best optical illusions that went viral and stumped the internet

dress white gold blue black

Is this dress blue and black or white and gold?
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This looks like a beach scene...

What do you see?
Twitter/@nxyxm

On July 2, Twitter user @nxyxm posted a confounding photo with a caption that posited that those who can see "beach, ocean sky, rocks, and stars" are artists.

... but it's actually the broken bottom of a car door.

See it now?
Twitter/@nxyxm

The shadow on the "sand" is actually the shadow of the car over a rocky road. The area where the ocean waves are breaking is actually the cracked plastic at the bottom of a car door in need of repairs.

Do these legs look oily to you?

Nevermind.
leonardhoespams/Instagram

This image went viral in October of 2016 after Hunter Culverhouse, an art student, posted it on Instagram. It looks like Culverhouse's legs are covered in oil.

It's actually just streaks of white paint.

Nevermind.
leonardhoespams/Instagram

With the image cropped, it's a little easier to tell what's really going on: streaks of white paint make it look like a glare of light is coming off of Culverhouse's legs. They're actually dry.

Culverhouse told INSIDER that the effect was completely unintentional. They took the photo after finishing up some homework for an art class.

"[I] had some white paint left on my brush and put random lines on my legs," Culverhouse wrote in an email. "Turned out to be a completely confusing picture for everyone on the internet."

Kendall Jenner seems to be missing a leg.

Where's her leg?
InStyle magazine/Instagram

Earlier this year, InStyle magazine posted an Instagram photo of Kendall Jenner, Kylie Jenner, and Hailey Baldwin hanging out together after the Golden Globes.

They are all very leggy. So it's odd that one went missing. Kendall's left leg is nowhere to be seen. Where'd it go?

It's under her dress.

Found it!
InStyle magazine/Instagram

Eventually, the internet figured it out. It was under her dress all along! If you look really closely, you can see the horizontal top of her leg. She's pointing her knee to her right and twisting her body forward to be more prominent in the picture.

This illusion of six girls with five pairs of legs flummoxed the internet.

What's going on?
jr0d7771/Reddit

Legless women are a staple of the viral optical illusion genre. This photo that went around Reddit in late 2016 showed six women sitting on a couch.

But — yet again — a leg was missing. The person sitting in the middle of the couch seems to have no legs at all.

What's really going on is a little more tricky.

This makes more sense.
Jacob Shamsian/INSIDER, jr0d7771/Reddit

If you look closer, you'll see what's really going on.

The woman in the middle of the couch does, in fact, have legs. She's leaning her torso to her left and her head to the right. So it's hard to tell that those legs on the viewer's left are hers.

The legs of the woman all the way on the left are also pretty clear. She's wearing black jeans.

So that leaves the person second from the furthermost left. If you look closely, you can see that she's also wearing black jeans. One of her legs is simply completely behind the other woman's legs. You can see a sliver of the other one in the image. It helps if you adjust the photo's lighting.

There's something off about this viral photo. Can you spot it?

Look closely...
what047/Imgur

This particular image went viral on Imgur, uploaded by a user going by the name of what047. It has the caption "It took me forever to find what was wrong here..."

Do you see it?

All the faces in the background are the same.

Look behind them.
what047/Imgur

You may have been looking too closely at the women in the foreground. Nothing is off about them.

But in the background, everyone has the same head. Someone edited the image so that everyone's head was replaced with one belonging to a curly-haired guy looking down.

The image's trick is a good reminder that the details you're looking for aren't always in the foreground. Sometimes they're in unexpected places.

Is this dress blue and black or white and gold?

You should know the answer by now.
Tumblr

The dress! How can anyone forget the dress? black and blue? white and gold? Why does it look different to everyone?

The original image was posted on Tumblr by a woman named Caitlin McNeill, a singer-songwriter from Scotland, after she sent the picture to her friends, who disagreed on the color.

It's black and blue. Here's the science behind why it looks different for different people.

Yup.
Screenshot / Roman Originals

It's black and blue.

The science of why people saw the dress differently is a little complicated, and scientists offer different explanations for some of the details. The peer-reviewed Journal of Vision even published several articles about it.

Stated plainly, the way your brain determines color relies on two things: the color of the object you're seeing and the color of the light source. The image was overexposed, meaning the light in the image overwhelmed the color of the subject. Parts of the dress were also in shadow. This all implies that the dress had a partial light makeup of bluish shadow, reflecting off the dress itself, and yellow light, from the store's bad lighting. Parts of the image also seem to indicate that the dress is backlit.

Depending on whether your brain saw the dress more in shadow or more in a direct light, you'd see the colors differently.

This looks like a 3D, urban city.

Hoerr/ Reddit

Daniel Hoerr posted a photo ofColorado's farmland to Redditafter he realized the flat land seemed to be 3D.

It's because of a phenomenon called color constancy.

The strawberries seem red anyway.
Carson Mell/Twitter

The image above, posted by "Silicon Valley" writer Carson Mell, separates specific pixels to show that they are, in fact, grey and green. They're not red.

Your brain may think they're red because of a phenomenon called color constancy. It's related to the science behind The Dress: Your brain looks at the color of the object and the color of the light to determine the color presented to you.

But the brain also knows that the color of the object is more useful than the color of the light for actually determining the color of the object. So it's trained to ignore information from the color of the light.

In this manipulated images, the color of the light has been manipulated so there's no red whatsoever in the image. But your mind recognizes the objects as strawberries, and it knows that strawberries (at least as most people know them) are red, so it understands the strawberries to be red even if the image has no red in it.

"You brain says, 'the light source that I'm viewing these strawberries under has some blue component to it, so I'm going to subtract that automatically from every pixel,'" Bevil Conway, a neuroscientist at the National Eye Institute, told Motherboard. "When you take grey pixels and subtract out this blue bias, you end up with red."

"Ambiguous cylinders" are somewhere between a circle and a square.

There's a simple and elegant explanation.
The Illusion contest/YouTube

If you pause the video at around the 15 second mark, mid-rotation, you'll see the object's "true" shape.

Ambiguous cylinders, Sugihara writes in a paper cited by Motherboard, are somewhere between a square and a circle. In this case, the shape also has wavy top edges. Depending on your perspective, your brain corrects the shape of the image to appear as a circle or a square. You can create the same illusion with more elaborate shapes that are made up of circles and squares, which is what Sugihara did with the other objects.

Your peripheral vision isn't very good.

There they are!
Perception

You should be able to see any dot you look at directly. But the ones in your peripheral vision pop in and out.

That's because humans simply don't have very good peripheral vision, as vision scientist Derek Arnold explained to The Verge. For something like this — black dots against grey lines — your brain simply makes the best guess it can to fill in the information. In this case, it just guesses the dots aren't there. The white in between the grey lines makes your brain think the dots are lighter than they really are. Thus, it just sees more grey.

"That can counteract the blurry black dot that is actually, physically there," Arnold told The Verge.

She's definitely not underwater.

There are a few clues.
maskari/Imgur

For one, you can't be both underwater and splashing into water at the same time. That makes no sense.

Furthermore, her hair is dry and her ponytail isn't floating around, which it would if she were underwater. The "air bubbles" are just drops.

Either overexposure or a digitally added filter makes the lighting look like she's underwater. But she's not, really.

Blurring the image shows that it's really a grid.

Here's what it looks like when it's blurred.
Victoria Skye

As Skye showed in her video, by blurring the image until the details disappeared, you can see the larger picture. The lines are, in fact, straight. They're perfectly parallel and perpendicular to each other.

These two train track segments are the same size.

But they don't look like it.
INSIDER

One example of the illusion went viral when BBC presenter Marc Blank-Settle posted a video of it on Twitter, using his son's train set.

Both curves in the track are the same size, but one the one on the left appears larger than the one on the right when they're next to each other.

Yes, really. The illusion is called the Jastrow illusion.

Here's how they look stacked on one another.
INSIDER

There are a few different theories for how the Jastrow effect works. But basically, your brain compares the two sides of the respective track pieces that are next to each other. So instead of comparing the right side of one piece to the right side of the other, it compares the right side of the left track to the left side of the right track, because those two sides are next to each other.

These are supposed to be sand dunes.

They don't look like hills.
Luca Parmitano/Twitter

While flying a few hundred kilometers over a desert in 2013, European Space Agency astronaut Luca Parmitano took a photo of some sand dunes.

"Like an Escher painting, sand dunes seem to reproduce the same shape indefinitely," he wrote.

A lot of people didn't see it. The photo looks like a bunch of pits, not hills. What's going on?

The floor itself is flat, but the curvy lines make it disorienting.

This carpet is hard to even look at.
WHS_Carpet/Twitter

Because of the way the carpet is crosshatched, bigger holes between the lines make it look like there's additional depth. In reality, it's still flat — just headache-inducing.

It's only an illusion: The floor is totally flat.

The floor is level.
@Duncancook10/Twitter

The design, only visible from one end of the hallway, is meant to stop people from running down it. It you look at it from the opposite direction, it's clearly part of a design.

"The inspiration was to create an entrance themed on illusions and [exceed] expectations of how tiles can be used," a representative of Casa Ceramica told INSIDER in an email.

You can watch how the company made it here.

The artist Liu Bolin made himself invisible. Can you find him?

He's in there somewhere.
http://www.kleinsungallery.com/

Liu Bolin, known to some as the "Human Chameleon," published a series of self portraits.

The one catch: It's hard to actually see him. He's camoflaged himself so he resembles the world around him.

When his photos were published in 2011in his book "Liu Bolin: The Invisible Man," they spread around the web. Can you find him in the photo above, for example?

When you zoom in, it's easier to see the shadows his body casts.

There he is.
Courtesy Klein Sun Gallery, © Liu Bolin

It takes up to 10 hours for Bolin to get painted, and he has to stay very still. This photo is just one of many examples.

This woman's face clearly doesn't look right.

Artist Mimi Choi.
mimles/Instagram

Mimi Choi's different face styles went viral back in April. She isn't modifying her face with Photoshop or using CGI. So what's going on?

She's a very talented makeup artist.

Another one of Choi's designs, which took four hours to put together.
Mimi Choi/Instagram

All of it is, in fact, makeup. Choi is a makeup artist who uses deep blacks to add illusory depth to her face.

"When I do illusions now, I draw my inspiration mostly from my surroundings, photography, paintings, and emotions," Choi told Allure. "I try not to look at other makeup artists's work too much and challenge myself to produce original, unique work."

She's not the only one to use makeup to create such dazzling images. The South Korean makeup artist Dain Yoon went viral in October for similar effects.

Like The Dress, no one could tell what color these shoes are.

Are these sneakers pink and white or grey and deal?
dolansmalik/Twitter

In October, a single sneaker went viral and caused a debate as virulent as the one over The Dress: Was it pink with white trimmings? Or grey with teal?

It's pink.

Yup. Definitely pink.
DSW

As with The Dress, you can blame lighting for playing tricks on your eyes.

If you look at the original photo, you'll see that there's a tealish tint on the hand holding the shoe, indicating that the image's lighting had that color artificially increased.

Also, DSW sells the shoe, pictured above, which you can clearly see is pink.

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