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Our top 10 optical illusions of 2021 will make your head hurt

2021 on an optical illusion background
(Image credit: PCMag/Future)

What a year it's been, and we're not talking about the C-word. From the rise of the metaverse to the Nintendo Switch, it's been a jam-packed 12 months full of innovation, creativity and of course, optical illusions. That's right, over 2021 we saw so many perplexing optical illusions, so many in fact, that we've decided to narrow them down in this roundup of our favourite mind-bogglers of the year. 

While we haven't included the official the Best Illusion of the Year (yes, there's an official contest), we still have several brilliant designs that we guarantee will blow your mind. And if you fancied your chances at winning the competition next year, why not check out our guide on how to create 3D optical illusions?

01. Are these circles actually moving?

A spinning optical illusion gif

We're so confused (Image credit: jagarikin on Twitter)

Our brains still can't comprehend how this illusion works. Apparently, the spinning circles remain in the same location and at the same size throughout this gif, but because of the directions of the arrows in the centre, it looks as though the circles are changing. 

We know, we can't believe it either. We're about as baffled as when we first wrote about the magic spinning wheels back in November. 

02. Cuteness overload 

@litto_lychee (opens in new tab)

try this on your pets and duet me 😻🤣 #catsoftiktok #catvideos #funny #fyp #foryou #opticalillusions

♬ Spongebob - Dante9k (opens in new tab)

Now we know that this isn't exactly an illusion, but considering it has an optical illusion and a cat in it, we just had to include it in our roundup. Back in October, we discovered that cats are just as baffled by optical illusions as we are, when a user on TikTok posted a video of their cat reacting to an illusion

The cat stares long and hard at the illusion, just for it to look utterly confused when it pounces on it and nothing happens. The actual illusion that the cat was reacting to actually sits proudly on our roundup of the best optical illusions, so it's no surprise the feline reacted so strongly to it. 

03. The black and white coloured photo

A seemingly coloured photo of a group of people

How is this photo black and white? (Image credit: Chuwa Francis)

You might have to double-take at this deceitful photo because at first glance it looks like it's in full colour, but if you look a little closer you will realise that only a tiny percentage of the photo is in colour.  

This clever illusion uses something called a 'colour assimilation grid'. The grid is made up of many coloured lines, which are then placed over the black and white photo. One Twitter user (opens in new tab) was able to calculate that only 36% of the photo was actually coloured, so technically speaking our brains are just filling in the gaps, to make the image seem in colour. If you'd like to learn more about this illusion, then make sure you check out the original colourful black and white illusion piece we wrote back in September. 

04. Are these all the same colour?

It might look like all six of these squares are a different colour but unbelievably, they're all exactly the same. Back in August, we were introduced to these magic squares that look like they change colour based on where on the gradient background they sit. In a video posted on TouTube (opens in new tab), you can see the square colour change as it moves around the background. 

This illusion is so effective because of the way our eyes and mind perceive colour. Apparently, what we see is all based on how we judge the colour and brightness of the square by comparing it with the other colours or lighting around it. And if that all sounds like a foreign language, then why not brush up on your colour theory knowledge with our guide?

05. This viral TikTok trend with an illusion twist

If you've been living under a rock for the past couple of years, you may have missed the rise of the social media app TikTok. During its reign, there have been hundreds if not, thousands of viral TikTok trends falling in and out of fashion. One that had a particular grip of 2021 though, was the milk crate challenge, where users attempt to climb up an unstable structure made of milk crates  – and spoiler, lots of people got hurt. 

To combat the trend's potentially dangerous outcome, one user decided to create this fabulous street art illusion, so passers-by could climb to the top of the milk crate tower without injuring themselves. There was even a dog who gave the challenge a try. 

06. This true Cyan colour 

@kbacon (opens in new tab)

You’ve probably never seen this color before... #womeninstem #voiceacting #science

♬ Blade Runner 2049 - Synthwave Goose (opens in new tab)

The exciting thing about this illusion is that there is very careful science behind it, which makes the illusion A) utterly confusing and B) incredibly cool. The video, posted on TikTok, explains how if you stare at the white dot in the middle of the video for 30 seconds, it will reveal a colour your eyes will have never seen before – true Cyan. 

We know it sounds farfetched, but this is seriously cool and who doesn't want to see a colour they've never seen before? (Speaking of hues, what did you think of Pantone's colour of the year?) If you're interested in the science behind this incredible illusion, we explain more about how it works in our original true cyan piece

07. Staircase to heaven

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Aptly named the 'Staircase to Heaven', this cleverly designed sculpture tricks the mind into thinking that these stairs go all the way up into the sky. From one angle it looks as though there are a set of hundreds of giant stairs, but as the camera pans around to see the sculpture from the side, you can see that the design is hardly even 3D.

The sculpture was designed by Strijdom van der Merwe (opens in new tab), who says he likes to create land art, that compliments the sculptural forms" that "take shape in relation to the landscape". We think the design is pretty spectacular, and if you're a fan there is plenty more to read about the Staircase to Heaven in our piece from earlier in the year. 

08. Soulwax secret album cover

The Soulwax album cover

If you squint you might be able to make out the album title (Image credit: Soulwax)

At first glance, this looks like an unassuming illusion that frazzles your eyes a little bit, but we dare you to look again a little harder. In fact, if you squint at this illusion, you might be able to see what we're talking about. 

That's right, this is the album cover for the artist Soulwax, and if you look very very carefully in the top left corner, you might be able to work out the name 'Soulwax' and the title of the album 'NY Excuse'. Even though we first saw this optical illusion album art a while ago, we still can't quite believe that words are hiding in plain sight. 

09. Three identical cars on a hill... or not?

@beatonthebeeb (opens in new tab)

♬ HEART - Pistol Shrimp (opens in new tab)

We've no idea how this illusion works, we only know that we're confused. According to the TikTok video, all three of these cars are exactly the same size, despite looking like they increase in size from the bottom of the hill to the top.

The TikTok user Beatonthebeeb (opens in new tab) explains that our brain enlarges the car that's furthest away because it's on a hill. We were sceptical of the illusion at first, but after we measured the cars next to each other on our original post about the car illusion to check if they actually differed in size, we were baffled to see that they were all exactly the same.  

10. Jumping ninjas illusion

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Here's another perplexing optical illusion gif where it looks as though the image is moving when it's not. Because of the way the characters change colour it looks as though they are progressively moving across the screen when in reality they aren't moving at all. 

A user on Twitter explained that that is a "reverse-phi illusion," which according to Stanford University (opens in new tab), "If a bright point appears at one position, and then reappears at a position shifted to the right, we tend to see a single object moving left to right". Even with an explanation, we're still baffled by this mesmerising illusion.

We might have to take a few minutes to sit down and unscramble our brains after looking at so many bewildering optical illusions. But if you still haven't had enough of the illusions, then why not check out our roundup of the most mind-blowing trompe l'oeil illusions?

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Amelia is Creative Bloq’s Staff Writer. After completing a degree in Popular Music and a Master’s in Song Writing, Amelia began designing posters, logos, album covers and websites for musicians. She now enjoys covering a range of topics on Creative Bloq, including posters, optical illusions, logos (she's a particular fan of logo Easter eggs), gaming and illustration. In her free time, she relishes in the likes of art (especially the Pre-Raphaelites), photography and literature. Amelia prides herself on her unorthodox creative methods, her Animal Crossing island and her extensive music library.