40 mind-boggling optical illusions that have stumped the internet

Courtesy of Duncan Cook/Casa CeramicaBelieve it or not, this floor is completely flat.
  • Optical illusions often go viral online.
  • Recent examples include an image with a hidden animal that appears if you shake your head back and forth and a hand-swapping trick.
  • Some illusions – like the infamous dress that appeared either blue and black or white and gold – have divided the internet.
  • INSIDER rounded up 40 confusing images, from classic optical illusions to baffling designs.
  • We’ve also included explanations for some of these illusions, which illustrate how our brains process and interpret colour, peripheral vision, size, and more.

In the past few years, the internet has given us The Dress, a photo of a mysterious missing leg, and this disorienting floor design.

If you’re still hungry for more, INSIDER rounded up a mix of classic optical illusions, baffling viral photos, and mind-boggling designs that will leave your head spinning and illustrate how our brains process and interpret colour, peripheral vision, size, and more.

One quick note: We’ve included explanations for many of the images, so scroll down slowly if you don’t want to spoil the illusion.


You have to shake your head back and forth to see the animal hidden in this illusion.

medickinson/TwitterAny guesses what the animal is?

Dr. Michelle Dickinson, a nanotech engineer,posted the optical illusion on Twitter in January 2019.


The hidden animal is a cat — and you don’t have to shake your head to see it.

medickinson/TwitterThe cat appears if you look at a very small version of the original illusion.

As INSIDER’s Gabbi Shaw previously wrote, if you zoom out on the original illusion, or look at a very small version of the image, the cat should become clear.


A video of this hand-swapping trick baffled the internet.

kay_dera/TwitterChidera Kemakolam’s video has racked up 3.47 million views.

Chidera Kemakolam, who goes by kay_dera on Twitter, tweeted a brief clip of herself doing the trick in late August 2018.

In the video, Kemakolam starts by holding her left hand up to the camera, with her open palm facing the camera. After that, she wraps the fingers of her right hand around the palm of her left hand. Kemakolam then pushes both hands toward the camera, during which her right hand seemingly breaks free and appears, balled up into a fist, in front of her left hand in seconds.


The key to the trick is quickly making a fist with your front hand.

kay_dera/Twitter and Lucy Yang/INSIDERThe hand that starts in front stays in front.

Your hands never actually swap positions.


The amorphous shape at the bottom of this painting has confused people for centuries.

Wikimedia Commons (Public domain)The painting resurfaced and went viral in late July 2018.

Titled “The Ambassadors,” this painting was finished in 1533 by German artist Hans Holbein the Younger. It’s currently on display at the National Museum in London, UK.

When you look at the painting head-on, you’ll see what appears to be a large, deformed object at the bottom. But when viewed from a particular angle, the blob turns into a human skull before your eyes.

According to researcher Phillip Kent, this painting is one of the most famous examples of an anamorphosis – an irregularly shaped image that appears in its “true” form when viewed in an “unconventional” way – in art.


What colour are the circles in this photo?

novickprof/TwitterMost people see four different circle colours.

This colourful image went viral in mid-July 2018 after its creator, University of Texas professor, Dr. David Novick, shared it on Twitter.

Despite what you may see, it turns out all the circles are actually the same colour. “The differences are subtle, though, and depend on the size of the image when it’s viewed,” Dr. Novick tweeted.

Dr. Novick’s image, which he calls “Confetti,” is an example of a classic optical illusion known as a Munker illusion. According to Danish professor Michael Bach, the Munker illusion reveals how much our perception of colour is influenced by other surrounding colours.


At first glance, this photo seems to depict a man leaning over and embracing a woman who is sitting at her desk.

Boom_likean808/TwitterWho’s wearing these black heels?

In May 2018, a Twitter user named CJ Fentroy posted a picture of what appears to be two coworkers laughing and hugging. It also looks like the guy in the photo is rocking a light blue shirt, white skinny jeans, and black heels while the woman is wearing a plaid shirt in shades of magenta.

It’s a cute but otherwise uneventful photo that you might just scroll past online if it weren’t for Fentroy’s caption. “At first, I thought he was wearing the heels,” the Twitter user wrote.


If you look at the photo again, you’ll start to question whose legs you’re actually seeing.

Boom_likean808/Twitter and Lucy Yang/INSIDERThis might help you break it down.

Upon closer inspection, it’s hard to tell whether the guy in the photo is leaning over, with his head positioned above the girl’s, or whether the girl is leaning over, with her head perched on the guy’s left shoulder.

But the general consensus online seemed to be that the woman in the photo is the one wearing heels while the man is actually sitting down.


Depending on how you look at it, this illusion looks like Ben Stiller or Beyoncé.

People were creeped out by this optical illusion after “The Late Late Show” host James Corden tweeted a photo of it in May 2018.

Originally created by Chris Frady (Reddit user Shikaca), this image first went viral in 2015 – and it was made by combining two photos of Zoolander and Beyoncé.

At first glance, the illusion looks like a blurry photo of Ben Stiller’s Zoolander character from his 2001 movie of the same name. But if you squint your eyes, Stiller’s face seems to disappear; in its place, Beyoncé’s face materialises. Her face also appears more clearly, compared to Stiller’s face, when you look at a smaller version of the image or stare at it from a distance.


The Zoolander-Beyoncé photo is a variation of a simple optical illusion known as a “hybrid image.”

One famous example of a hybrid image overlays the faces of Albert Einstein and Marilyn Monroe, as seen above. As Aude Olivia, the principal research scientist at MIT’s Computer Science & Artificial Intelligence Lab, previously explained to Wired, this illusion is often used to study how our brains process visual stimuli and sight.

According to Olivia, who has created and used hybrid images in her research for decades, our eyes see “resolutions with both high spatial frequencies (sharp lines) and low ones (blurred shapes).” Up close, we focus on features with high frequencies, such as wrinkles or blemishes. But from a distance, sharp details become less visible and we instead register features with low frequencies, such as the shape of one’s mouth or nose.

Hybrid images work by combining the high frequencies from one photo with the low frequencies from another. The result is a picture that can be perceived in two different ways, depending on the distance from which you look at it.


If you focus on this image for about 30 seconds, it will disappear completely.

In April 2018, an eye-care practice in Horsham, Pennsylvania,tweeted an optical illusion that left some people in disbelief. The image, posted by Dr. David McPhillips of Primary Eye Care Associates, disappears after approximately 30 seconds, when you focus on just one fixed point in the graphic.

So how does it work? Well, this mind-boggling effect is actually a variation of a famous optical illusion called Troxler’s fading circle. Discovered in 1804 by Ignaz Troxler, a Swiss physician and philosopher, the Troxler effect illustrates the human brain’s efficiency.

In simplest terms, your sensory neurons tend to filter out information that is constant – stimuli that your brain has deemed non-essential and non-threatening. As Live Science’s Brandon Specktor explained, this ability to adapt quickly to stimuli allows your brain to focus on things that are actually important.

When you force your eyes to focus on one point, the way you do with Troxler-style illusions, your brain receives no new information to process. At this point, stimuli in your peripheral vision take on the nature of their surrounding environment – in this case, a white background – as your brain “fills in” information it has deemed unimportant to process.


This person’s tattoo makes it appear like he has a giant hole in his arm.

RedHood000/RedditIt looks like a never-ending whirlpool.

A photo of this tattoo went viral in February 2018 after it was posted on the subreddit r/Damnthatsinteresting. It’s not yet clear who the original artist behind the tattoo is.

As INSIDER’s Jacob Shamsian explained, the tattoo’s design creates an illusion of infinite depth, thanks to the placement of “progressively smaller rectangles” on the inside of the spiral.


What colour is this dresser?

agamiegamer/RedditDo you see pink or blue?

In December 2017, Reddit user agamiegamer posted a photo of this dresser to the subreddit r/blackmagicf—ery. “What colour do you see: pink and white or blue and grey?” the user titled the post.

People were immediately torn, with some seeing pink and white, others seeing blue and grey, and a few seeing “very light blue-green and pink” or “lime green and grey.”

Eventually, Reddit user agamiegamer revealed the dresser was actually painted blue and grey in real life. When some were still sceptical, Reddit user romeroleo offered the following explanation: The “reddish” lighting of the photo makes the “unsaturated grey” parts of the dresser appear pink. The lighting also “warms” the “cold” blue parts of the dresser, which makes them appear white.


At first glance, this looks like a normal newspaper.

Don’t believe everything you think you see.


But look closer and you’ll realise that it actually has a hidden “3D” kitchen.

Creative director Felipe Salazar and graphic designer Karen Castañeda recently turned a newspaper into an ad for HiperCentro Corona supermarket. The two artists manipulated the paper’s text to look like a “3D” kitchen, using their design to add the illusion of depth. In reality, the paper is completely flat.


Although you may see a bunch of swirling circles, this image is actually completely still.

Cmglee/Wikimedia CommonsNo, this isn’t a GIF.

The image above was inspired by the famous illusion “Rotating Snakes,” created by Japanese psychologist and professor Akiyoshi Kitaoka in 2003.

Both are examples of a peripheral drift illusion, in which we perceive still images as moving ones. Interestingly enough, when you stare at one part of the photo without moving or blinking your eyes, that part stops “swirling” (while the circles in your peripheral vision continue to “move”).

You can read about the science behind this phenomenon on Business Insider.


Is this cat going up or down the stairs?

9GAGOnce you see it, you can’t unsee it.

This innocent photo of a cat went viral back in 2015 as people wondered whether the animal was going up or down the flight of stairs.

Internet users used everything from architecture to biology to defend their answers to the hotly debated question. INSIDER’s Megan Willett, for example, broke down why the cat is “definitely” going down the stairs – and after reading her explanation on Business Insider, I’m convinced.


This photo of two people hugging confused the internet last year.

ImgurIt looks like the man’s thighs disappear.

The post went viral after Reddit user Blood_Reaper shared it online, along with the caption, “This hurts my brain….”

People couldn’t figure out who was initiating the hug, as the man in the photo appears to have two pairs of legs.


If you focus on the man’s shorts, you’ll figure it out.

ImgurA classic trick.

The man’s shorts are black on the side and white in the middle, making them appear like they’re white pants that the woman is wearing.


Tiles A and B on this checkerboard are the exact same colour.

Wikimedia CommonsYes, really.

This classic optical illusion was first published in 1995 by Edward H. Adelson, a professor of vision science at MIT.


Called the “checker shadow illusion,” the effect has to do with the way our brains interpret colour and shadow.

Wikimedia CommonsHere’s some proof.

As Slate explained, “your brain is always comparing things.” Square A is surrounded by lighter squares, making it appear darker, while Square B is surrounded by darker squares, making it look lighter. The shadow also “messes with your perception” and “amplifies the effect,” Slate added.

If you’re still not convinced, open the image in Photoshop, use the Dropper or Colour Picker tool to select the colour in Square A, and draw a straight line to Square B (or vice versa).

MIT also has a great resource that explains the science behind this phenomenon.


Is this shoe pink and white or teal and grey?

dolansmalik/TwitterWhat colour is this shoe?

Earlier this month, this humble shoe went viral after people started debating whether it was pink and white or grey and teal. It felt like the second coming of The Dress debate from 2015, in which the internet could not agree on the true colour of a bodycon dress.


The shoe is actually pink and white in real life.

DSWVans’ Ward Lo Sneaker in Blush ($US55).

Just like the photo of The Dress, the original photo of the sneaker was taken in poor lighting with a bluish tint, INSIDER’s Susanna Heller explained. Your perception of the shoe’s colour depends on your individual sensitivity to the lighting in the image.

Keep reading to learn more about this phenomenon.


Is this dress blue and black or white and gold?

swiked/TumblrThe dress that broke the internet.

In 2015, the debate over the true colour of this dress spawned hundreds of online comments, articles, and even peer-reviewed scientific analyses. People either saw it as black and blue or white and gold – and both sides were convinced that they were right.


As you probably know by now, the dress turned out to be black and blue.

Screenshot / Roman OriginalsRoman Originals’ Lace Detail Bodycon Dress in Royal Blue ($US58).

There are countless explanations you can read online about why people see the dress as two completely different colours.

In simplest terms, it all has to do with how your brain processes colour. Basically, light bounces off objects in the world and reaches your eyes in “a mix of wavelengths,” which your brain then interprets as colour.

As Slate’s Pascal Wallisch explained, “this mix depends on two things: the colour of the object and the colour of the light source. […] To achieve what colour vision scientists call ‘colour constancy,’ the brain calculates colour-corrections for an image on the fly. It takes note of the illuminating light and tries to figure out how it might be affecting the colour of an object.”

Since the photo of the dress was taken in poor lighting with a bluish tint, your brain either sees the dress in shadows (and colour-corrects the dress to be white and gold) or in “a fair amount of illumination” (and perceives the dress as blue and black).


Here’s another example of colour constancy: these strawberries aren’t red.

Akiyoshi Kitaoka/TwitterDespite what you may see, there’s no red in this photo.

Like “Rotating Snakes,” this illusion was also created by Japanese psychologist and professor Akiyoshi Kitaoka, who studies visual perception at Ritsumeikan University. Professor Kitaoka shared the photo on Twitter earlier this year.

The colour red has been completely removed from the image, yet people still see red strawberries. Why?

Well, as INSIDER’s Jacob Shamsian explained, the brain “knows that the colour of an object is more useful than the colour of a light source” in determining the colour of an object. Thus, “it’s trained to ignore information” it receives about the colour of a light source. Since your mind recognises that the objects in this photo are strawberries, and it knows that strawberries tend to be red, it colour-corrects the grey and green pixels in the image to be red.

Still confused? Read Shamsian’s full explanation here.


There are a total of 12 black dots in this image, but you can’t see them all at once.

First published in 2000 in the academic journal “Perception” by Jacques Ninio and Kent A. Stevens, this illusion went viral after Professor Kitaoka shared it on Facebook and game designer Will Kerslake‏ reposted it on Twitter.

While you should be able to see any dot you look at directly, the dots in your peripheral vision seem to appear and disappear. Why? Well, in simplest terms, our peripheral vision sucks.

You can read about the science behind this phenomenon here.


Can you find the cat in this photo?

waterhauler/RedditIt’s hidden in plain sight.

Originally posted by Reddit user waterhauler, this simple photo went viral in 2016.


Reddit users had a hard time finding the tan-coloured cat, which blended in with the piles of chopped wood.

“That took entirely too long,” one Reddit user commented. “I thought maybe it was just a knot in that tree bark in the background.”


This wavy floor is actually completely flat.

Courtesy of Duncan Cook/Casa CeramicaAn optical illusion made of 400 tiles.

This floor design by UK-based tile company Casa Ceramica recently went viral on Reddit.

Installed in the entrance to one of the company’s showrooms in Manchester, the illusion stops people from running in the hallways.

If that’s not trippy enough, the illusion only works when you face the showroom’s entrance. The “dent” in the floor disappears when you look at it from the opposite perspective.


Similarly, this carpet looks like it’s full of giant sinkholes.

WHS_Carpet/TwitterTread carefully.

In September, Twitter account @WHS_Carpet – which specialises in calling out “bad carpets” – brought this disorienting photo to the internet’s attention. While the floor is completely flat, the carpet’s designer added large spaces between certain lines to add depth and create a crater-like effect, INSIDER’s Jacob Shamsian explained.


The horizontal grey lines in this image look slanted, but they’re actually completely parallel.

Fibonacci/Wikimedia CommonsDoes your head hurt yet?

This famous image was named the café wall illusion by psychologist Richard Gregory in the 1970s. It’s a classic optical illusion that dates back to the late 1800s. You can learn about the science behind the phenomenon in Gregory’s 1979 paper here.


Here’s another example of the “café wall illusion.”

Courtesy of Victoria SkyeVictoria Skye’s ‘Skye Blue Café Wall’ illusion.

This version of the classic optical illusion won second place in the Neural Correlate Society’s “Best Illusion of the Year Contest” in 2017.


When the image is blurred, you can see that the lines are indeed perfectly parallel and perpendicular to one another.

The illusion’s creator, Victoria Skye, blurred the image to prove that the lines are straight.


Can you spot something unusual about this Leonardo da Vinci painting?

“Salvator Mundi” is a painting of Jesus Christ that was lost, rediscovered, and identified as a da Vinci work in 2011.

However, some historians are questioning the authenticity of the recovered painting given one particular detail, the Guardian wrote in October.


The glass orb that Christ is holding doesn’t distort light the way it should in real life.

Seth Wenig/AP and Stuart Mack/ShutterstockThe glass orb in the photo (left) versus a real glass orb.

“Solid glass or crystal, whether shaped like an orb or a lens, produces magnified, inverted, and reversed images,” writer Walter Isaacson explains in his biography of da Vinci. “Instead, Leonardo painted the orb as if it were a hollow glass bubble that does not refract or distort the light passing through it.”

It’s an especially strange choice given the artist’s otherwise careful – and scientifically accurate – depiction of light in his works. That said, Isaacson, and many others, still believe that the painting is authentic. Perhaps, some have argued, da Vinci intentionally ignored physics in order to highlight Christ’s divine powers.

The Guardian article is also now the subject of a legal complaint made on behalf of Christie’s International Plc, the auction house that is due to sell “Salvator Mundi” later this year on November 15.


There’s a phone hidden somewhere in this picture.

Jeya May Cruz Estigoy/FacebookThis image stumped the internet last year.

A Facebook user first shared this photo in 2016, and her post has since been shared thousands of times.


Thanks to its floral case, the phone blended in perfectly with this patterned rug.

Jeya May Cruz Estigoy/Facebook and Lucy Yang/INSIDEROne way to lose your iPhone for good.

Did you see it?


The neon blue lines make it appear like there is a light blue circle in the middle of this image, but the background is white throughout.

Known as neon colour spreading, this classic optical illusion was first documented in 1971 and later rediscovered by H.F. Van Tuijl in 1975. While the exact causes of this phenomenon are still unclear, you can read about several theories here.


This photo of Kendall Jenner, Kylie Jenner, and Hailey Baldwin went viral earlier this year — but not for the reason you might think.

InStyle Magazine/InstagramCount the number of visible legs in the photo.

When InStyle shared this photo of the three women hanging out together after the Golden Globes, people were quick to point out that Kendall’s left leg seems to be missing.


Kendall’s left leg was hidden under the folds of her dress.

If you look closely at Kendall’s dress, you can see the outline of her left leg against the orange fabric. As INSIDER’s Jacob Shamsian explained, the model is pointing her left knee to her right side and twisting her body around to look directly into the camera.


Despite what you may think, the grey rectangles under columns A and B are the exact same colour.

Zhengyi4411/Wikimedia CommonsYou can test it for yourself in Photoshop.

Discovered in 1979 by Australian psychologist Michael White, this famous effect is known as White’s illusion. Since then, researchers have proposed several theories to explain the cause of this illusion – you can read about them here.


Is this child underwater or not?

maskari/ImgurConfused? Me too.

The year that gave us The Dress also gave us this viral photo of a girl who appears to be underwater at first glance. However, she also looks like she’s jumping into water, which makes no sense.


She’s definitely not underwater — here’s the proof.

maskari/Imgur and Jacob Shamsian/INSIDERHer hair is completely dry.

While the filtered light and air bubbles make it seem like the girl is underwater, a few clues prove that she’s not.

As INSIDER’s Jacob Shamsian pointed out, her hair is dry, her ponytail isn’t floating in the water, and the “air bubbles” are actually just drops of water.


The two orange circles in this image are exactly the same size.

Wikimedia CommonsThe orange circle on the right looks much bigger.

Discovered by German psychologist Hermann Ebbinghaus, this optical illusion was popularised by British psychology Edward B. Titchener in 1901.

Thus known as the Ebbinghaus illusion, or Titchener circles, the effect illustrates how our brain “uses context to determine the size of objects.” Since the blue circles surrounding the orange circle on the left are so large, the orange circle looks smaller in comparison. Juxtapose that with the tiny blue circles on the right, and the orange circle appears relatively larger.

In case you’re interested, this explanation by the Guardian breaks it down further.


Do these legs look oily or shiny to you?

leonardhoespams/InstagramDon’t believe everything you see.

An art student named Hunter Culverhouse first shared this photo on Instagram in October 2016. It went viral after people started debating whether Culverhouse’s legs were covered in oil or not.

It turned out the legs were completely dry.”[I] had some white paint left on my brush and put random lines on my legs,” Culverhouse told INSIDER last year. While the effect was unintentional on Culverhouse’s part, the white streaks made it look like a glare of light was reflecting off the student’s legs.


The red lines in this image look like they’re bending slightly outward.

The lines are actually completely straight. This classic optical illusion is called the Hering illusion, discovered by German psychology Ewald Hering in 1861.

Here’s how it works.


In 2016, yet another photo of a “missing” leg stumped the entire internet.

jr0d7771/RedditThere are six girls but only five pairs of legs.

Reddit user jr0d7771 posted this photo in December of last year, along with the caption, “Find the middle girl’s legs.”


People eventually figured it out.

INSIDER’s Jacob Shamsian broke it down last year. The woman in the middle, outlined in blue, is leaning her torso to her left and her head to her right, so it’s hard to tell which pair of legs is hers.

To make things more confusing, the two women on the left are both wearing black jeans. The woman second from the left has one leg completely hidden behind the other women’s legs. If you look closely, you can see a sliver of her other leg poking out.


The middle of these shapes look like they’re tinted by the light orange outlines, but it’s an illusion.

Robert P. O’Shea/Wikimedia CommonsThe area inside is completely white.

Known as a watercolor illusion, this effect occurs when a white area is surrounded by a thin, brightly-coloured line which is itself surrounded by a thin, darker border.

The illusion was independently discovered by Italian psychologist Baingio Pinna in 1987 and by Jack Broerse and Robert P. O’Shea in 1995.

Scientific American breaks down the science behind this phenomenon here.


Can you spot something unusual about this seemingly ordinary photo?

what047/ImgurDo you see it?

This image went viral on Imgur, after a user named what047 uploaded it with the caption, “It took me forever to find what was wrong here….”


All the faces in the background of the picture have been Photoshopped to be the same man.

what047/ImgurWere you focusing on the women?

The women in the foreground of the photo are a red herring. If you look closely at the background of the photo, you’ll figure out that everyone has the same exact head.


The blue diagonal line on the left looks longer than the one on the right, but they’re actually the same length.

Wikimedia CommonsDoes your head hurt?

Here’s a scientific explanation of this effect, known as the Sander illusion or Sander’s parallelogram.


The shapes in this photo are genuine mirror images of each other.

The Illusion contest/YouTubeThis picture hasn’t been Photoshopped at all.

Created by Meiji University professor Kokichi Sugihara, this illusion was named the “Best Illusion of the Year” in 2016 by the Neural Correlate Society.

It’s called the “Ambiguous Cylinder Illusion,” and you can see how it works on YouTube. If you’re still confused, you can read INSIDER’s breakdown here.


What’s wrong with this photo?

This seemingly normal photo of a brick wall went viral after UK resident Arron Bevin shared it on Facebook last year.


There’s a cigar hidden in the photo, wedged between the bricks.

Arron Bevin/FacebookThe ashy end of the cigar looks like a grey stone.

Were you able to spot it?


The train track on the left looks bigger than the one on the right…

Marc Blank-Settle/TwitterA classic illusion.

This version of a classic optical illusion went viral last year when BBC presenter Marc Blank-Settle posted a video of it on Twitter.


…but both tracks are exactly the same size.

Known as the Jastrow illusion, there are a few different theories as to how this effect is created.


Are these pits or sand dunes?

Luca Parmitano/TwitterThey look like pits to me.

European Space Agency astronaut Luca Parmitano took this photo of some sand dunes in 2013.

But why do the dunes in his picture look like craters?


If you look at the photo upside down, the illusion disappears.

Luca Parmitano/TwitterAh, there we go.

Basically, “your brain thought the sun was in the 1:00 position,” casting shadows from the upper right. However, the sun was actually casting shadows from the upper left, INSIDER’s Jacob Shamsian explained.

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