Optical illusions have been around for a long time, but thanks to the internet we are now seeing a new wave of viral mind tricks that capture people's imaginations and leave entire nations asking - was that dress really black or gold?
Here's a collection of the best optical illusions we've seen - let us know which are your favourites below!
The 'shiny' legs
are these legs shiny and oily or are they legs with white paint on them pic.twitter.com/7Z8e8F1JCZ— kayden (@kingkayden) October 26, 2016
At first glance, you probably saw this picture, shared on Twitter by Kayden Stephenson, as a pair of glossy legs - almost like they were made of plastic? Us too.
So what if we told you to take another look, and said that they're not actually a pair of super shiny pins - they're actually just covered in paint?! Mind. Blown.
The hidden phone
It may look like a just a table on a rug, but look harder and you will be completely baffled. This image, posted to Facebook, shows a phone completely blended into the carpet. We wouldn't want to accidentally drop our phone on this rug. It would never be found again! Thankfully, there's another image showing where the phone is actually hidden, in case your eyes are hurting from searching too hard...
The ambiguous cylinders
We've watched this video so many times, and we still can't get our brains around it! Watch as the cylinders change shape just by being turned in the opposite direction in front of the mirror... baffling, right?
The 3D creation is known as an ambiguous cylinder, and thankfully for us, its creator has also made a video explaining exactly how these crazy contraptions work. Every day's a school day!
This picturesque scene of a lake
At first glance this photo, from PlayBuzz, looks like a picturesque lake scene with mountains in the background. But is it? If you look closely at the top of the 'lake' you'll see it is in fact a stone wall which is onstructing the mountain view. Mind baffling!
The object-hiding car seat
Now here's a head scratcher for you! This image, posted to 9gag.com, has had the Internet in meltdown over it's eye trick. The image is hiding an object on the car seat - but can you see it?
After a while we spotted an iPad lurking on there, but it did take us longer than we'd care to admit! Did you spot it?
The hugging couple
When this photo was posted to Imgur with the caption 'This hurts my brain', they couldn't have been more right. This photograph of a couple hugging just makes no sense. Whose legs belong to who? How is she getting her feet in that position? They are simply defying the laws of physics... aren't they?
That is until we explain that the boy's swimming shorts are both white AND blue and cover what looks like two pairs of legs... do you see it now?
The shadow cat
How many cats do you see? One ginger moggy and his shadow? When Natural_Distortion uploaded this to Imgur, lots of people were quick to criticise the user for a bad Photoshop job on drawing in his cat's shadow, however these people failed to notice the eyes in the shadow! There are in fact two cats in the picture. Natural_Distortion captioned the image; 'I guess we should have named him Shadow.' One commenter said the picture was showing the 'Peter Pan' of the feline world. We couldn't agree more.
This mind blowing Gregg's optical illusion
Can you spot the Cheese & Onion Bake in this picture of Steak Bakes? pic.twitter.com/CjYXVnx6sl— Greggs (@GreggsOfficial) April 27, 2016
This pastry-heavy optical illusion has gone viral after confusing many a Twitter follower. Greggs tweeted the image above asking fans if they could 'spot the Cheese & Onion Bake in this picture of Steak Bakes?'
This ink drawing
What do you see when you look at this? It's been driving the internet crazy with hundreds of people saying they couldn't figure out what the shape was for hours!
Ready for a spoiler?
It's a cowboy!
These love hearts
These love hearts have been confusing the internet, because the hearts are actually the same colour.
Baffling, we know.
Apparently it's the surrounding stripes that are different colours, not the hearts themselves. And because our brains judge the colours of things in relation to the colours of surrounding things - we see the hearts as different colours.
All is explained in this handy little video...
The train track
My toddler's train track is freaking me out right now. What is going on here?! pic.twitter.com/9o8bVWF5KO— marc blank-settle (@MarcSettle) April 6, 2016
The newest optical illusion to go viral online is this child's train track.
When Marc Blank Settle was tidying away his son's railway he noticed something that completely 'freaked' him out, so he decided to share it with Twitter to get an answer.
The pieces of track are exactly the same size - they match end to end when placed on top of each other. But as soon as Marc put them next to each other, one of them seems half the size of the other. This all seems a bit much for our brains...
The red circle
Now we don't know about you but our eyesight isn't great at the best of times, and this latest optical illusion is really putting our retinas to the test!
Does the red circle look completely empty to you? Well look a little harder and you'll notice a faint outline, but can you see what it is? Some people claim to be able to see the drawing in bold detail, but we're not so sure... we can just about make out a horse with a mane. Can you?
The internet got up in arms (again) when one Tumblr user uploaded a picture of this jacket. Taira Rose from Tumblr page Dammit Michael posted the above picture along with the caption, 'I hate to make a new blue/black white/gold dress meme but my friend has this jacket and she says it's white and blue but i see black and brown pls tell me what you see.'
Much like Taira Rose and her friend team GoodtoKnow are divided. Settle the debate and let us know what colours you see in the comments below!
This bus puzzle is commonly used in schools to test pupil's logic and deduction, but it's leaving adults stumped. Children everywhere seem able to solve it in seconds, leaving their parents scratching their heads.
The National Geographic image shows a yellow school bus moving with arrows facing either direction - and all you have to do is work out which way the bus is moving.
To the untrained eye there are no obvious indicators which is the back or the front of the vehicle, but children quickly work out you can't see the passenger doors. The logic follows that the doors must be on the other side of the bus which you can't see. Meaning that in the UK the bus is travelling towards the right and in the USA it is moving left. Genius!
The Eye TestImage:TheSun
This latest optical illusion that has been going viral on Facebook asks viewers to look for the black and white 'c' in a row full of 'o' letters. Captioned an 'eye test' we are slightly dubious about the value of it compared to a trip to the optician... but it definitely makes our eyes feel a little tested. If you can spot it in under 60 seconds then you must be doing something right!
The Pyramid HoleImage:Mighty Optical Illusions
The first time you look at this simple mind trick,what do you see on top of the stone column that jumps out at you - a 3D pyramid or just an empty hole?
Now take another look, you can probably see your brain switch to viewing the other way round.
At first glace in the GoodtoKnow office we were definitely all fairly certain it was a pyramid. But taking a second look the angles and shadows make it look like the column is hollow in the middle. Or is that dark patch on the right-hand side conclusive that there is a 3D shape casting a shadow? Argh!
Needless to say it has boggled our minds a little - we can see both sides of the illusion but haven't been able to agree on what the picture actually shows. What do you think?
This tree full of faces
The image, called the National Leaders Tree, shows a collection of world leaders with famous faces such as Margaret Thatcher and Mikhail Gorbachev, but after identifying those it quickly becomes much more difficult.
The tree has risen and fallen in popularity over the years, but in the early hours of 1 January 2016, presumably when people were feeling a little worse for wear, it has quickly gone viral.
The photo has now been seen by over a million people on Facebook, none being able to agree on how many faces there are 'hidden in the tree'.
Some people claim they can see up to 10 faces made from the brances of the tree. How many can you see?
These snowmen hiding a pandaImage: Dudolf Facebook
Some users are commenting that they can't find the panda at all, asking others to inbox them with clues or the answer, while lots of people can identify the panda quickly.
One user, William PJ Kulich said, 'This is the only festive thing I've enjoyed this year so far. Good stuff.' Commenting on the success of the post online, Dudolf told i100.co.uk: 'The popularity of the 'panda' picture amazed me, I still can't believe it, but it makes me really happy! Glad to see how people like something I made.' So, can you spot the panda? Let us know in the comments below!
This little girl making a splash
Reddit user ma842 shared this picture of what appears to be an adorable little girl having fun in a pool, writing alongside, 'This girl looks like she's underwater and jumping into water at the same time' - and with that, a frenzy ensued, with people arguing about whether she's splashing about in shallow waters, or already in the depths.
Some commenters were quick to point out that the girls' hair doesn't look especially wet, but the water splash (or is it air bubbles?!) in front of her face threw many viewers off.
Others argued that the picture had probably been put through image editing app Instagram, giving it a washed-out look that altered the perception of the picture, but if you look closely at the girl's hands and feet, you can tell she's just jumping. Here in the office we're still split down the middle. Leave us a comment below if you're able to enlighten us!
Twitter user @totallymendes posted this picture of a shoe and two colours of nail polish on her account, with the caption: 'WHICH COLOR MATCHES THE SHOES THE BEST' - and the reason it went viral is that nobody can decide!
When you look at the bottle of polish on the left, it seems a perfect match - that is, until you glance at the bottle on the right, which seems to be exactly the same colour too!
No word yet on what colour @totallymendes finally opted for, but we're fairly sure it matched either way... because they're both the right shade! Right?
The FaceAnother popular illusion requires participants to simply stare at a white dot in the middle of the negative photo - right at the tip of the woman's nose.
After about 15 seconds, you then need to glance at the white blank space to the right of the photo... and voila! Did you spot it?!
If it's worked, you should have seen a pretty brunette woman's face, in colour, flash up before your eyes on the space next to the negative. Freaky!
How does it work? This kind of optical illusion is known as a 'negative afterimage', which is caused by the cells in the eyes, called ganglion cells, sending messages to the brain by identifying colours in pairs of primary colours.
Dr Juno Kim, from the University of NSW School of Optometry and Vision Science, told Daily Mail Australia that 'when you look at something that, for example, is yellow for a long period of time, you stimulate the cells that are positively sensitive to yellow - so in the yellow and blue channel.'
'The cells' activity increases and after a bit of time the activity fatigues and declines. When you then direct your gaze at a uniform background - let's say a grey wall - then what happens is that the cell doesn't return to its resting activity, it goes much lower than that. It's that decline - the weakening of the yellow code - that codes for the opposite colour to become stronger, so you'll see blue.'
The DressNow one of the most famous optical illusions of all time, this dress illusion took the internet by storm in February, when Tumblr user swiked posted this image, with the caption:
'guys please help me - is this dress white and gold, or blue and black? Me and my friends can't agree and we are freaking the f*ck out'
Needless to say, internet users were divided - and in the GoodtoKnow offices, we still can't decide seven months later!
Blimey - all of this blue, black, gold, brunette stuff is messing with our heads - who knew a white and blue face, a party outfit and some nail polish could cause so much excitement?!
Did the optical illusion work for YOU - or have you seen an optical illusion that's even better? Leave us a comment and let us know!