We've talked about them before here on dong and I've talked about them over on Vsauce3,

specifically in the video, Impossible Objects. Link down in the description.

There I talked a bit about MC Escher, the painter known for his fascination with illusions

and impossible shapes.

Now one of his most famous works is Metamorphosis, which depicts a series of repeating tessellated

objects morphing into other objects by breaking down into their simplest shapes and then into

newer more complex ones.

He made a whole bunch and you can make your own at escher.ntr.nl/en/mmm.

It's a pretty cool website. Here's what it looks like.

Wow.

Whoa.

Trippy.

MetamoFUNsis

That's a dong, something you can do online now guys.

One of the most basic tricks you can play on your senses is with lines.

The human brain is incredible, but it's not very fast, so it has to guess what's

going to happen next so it's not always late to the game.

One way it does this is by tracking the light that hits your retinas.

Many of the most common illusions are built to take advantage of this.

If we take this picture of Michael and add some lines he starts to get a little warped

and appears to be shifting and stretching like some sort of smart monster.

Also if you're wondering about this, this is a tiny toy

for my dog. I have a dog now. His name's Fajita. I love him.

Our brains add lines to moving objects to help us guess where they're coming from

and where they're going.

We can also play with lines at konsumer.js.org.

Now one of the ones we have here is a cat animation and it's similar to the illusion you get while watching a video.

It might look like there's actual motion happening, but really it's just a quick series of flashing

images.

Sped up really really fast you can see how each pixel is read from left to right one

after another.

In fact this illusion, called a zoetrope, is the direct ancestor of film.

So this website let's you make your own versions of this pre-video phenomenon.

You can put in any set of frames and the website with split them into overlapping lines of different

thickness.

As you pass the bar over them, some frames are blocked while the one you want to see

in the moment passes through.

The concept of the illusion of video isn't new to us because we've lived with video for all of our lives.

But when the concept of moving pictures, which comes from the Persistent Vision illusion, first

appeared, it was an incredible invention.

Almost immediately after the invention of film, another illusion was added to it, the

illusion of 3 Dimensional film.

Most people have an image of 3d films being red and blue filtered glasses and they'd

be right, but that technology is as old as 1915.

These days 3D films are make using a different technique, called polarization.

Normally when light hits a surface, the light scatters randomly in all directions.

In order to fake a 3D image, you have to project two slightly different angles onto the same

surface and then “polarize” the light in order to make it more easily filtered out

by those paper glasses but now they also have plastic cool ones, Jack.

Guess you never got the cool plastic ones that they have for specific movies

like the Nightmare Before Christmas. They release that movie sometimes again around Halloween

and they have 3D glasses for it and they're pretty cool.

Here's a photo of them.

Now there are other ways to trick our brains into seeing 3d images.

Stereograms, also known as Magic Eye Puzzles, are a particularly strange set of illusions

that were very popular in the 80's and 90's. Back when I was a little baby

person.

And it takes advantage of the way our eyes process 3d images.

This website lets you make your own.

Just upload an image and the website will create your very own Magic Eye Puzzle.

And there's also some other parameters you can put in if you want.

If you've ever crossed your eyes looking at a wire fence or some other repeating pattern

and gotten your eyes kinda stuck, you've already experienced this trick to some extent.

Because each eye is relaying a slightly different image to the brain the brain has to guess

when it's looking at one thing, and when there are two things that look the same your

eyes can get confused.

Stereograms use this trick to “lock” your eyes in a position that makes the differences

between them appear to be a 3D image.

So remember kids, don't trust your eyes, don't trust your brain.

The only thing you can trust is your DONG.

Now links to where you can make your own illusions is in the description but before we do that

let's meet my dog.

This is little Fajita.

Fajita's a beautiful boy. He's 10 weeks old. I just got him a few days ago.

And I love him so much.

Oh the dog's gone! It was an illusion!

You know what else is an illusion? Reality.

But if you wanna explore some cool websites links to the ones we talked about are down in the description.

And if you want more DONGs in your life there's a playlist right here.

Alright I'm gonna go play with Fajita.

And then I'm gonna drink a sparkling water and who knows maybe I'll have a sandwich or something.

I'm not entirely sure I haven't really thought that far ahead.

Uhh okay. And as always

Thanks for watching.