My name is Michael

And if you know me at all you know that I love tabs. I have tabs open on my phone, on my laptop, on

my desktop. Just hundreds of them thousands of them saved in my history

I like to collect websites, which are things you can do online now guys

I went through my collection recently and

Pulled out all of the ones that were optical illusions

These are illusions that I've discovered in the last few months

or was reminded of in the last few months that I wanted to remember and I figured hey

I'll just share them with you guys here in a DONG.

So let's begin. Now you cannot talk about optical illusions on the internet without talking about Michael Bach. His website is

phenomenal. It's interactive first of all which means that you can really play around with the parameters that make the illusion work.

I want to start today with the ghostly gaze.

Illusion all right now take a look at this person's face

She appears quite clearly to be looking to the left, right?

But now let's turn down the blur and see what she's really looking at

AHH!!! Us.

Pretty spooky right? If you blur the image. She appears to be looking to the left, but take away the blur

She's looking right at you. So what's going on here? Well this is called a hybrid image

It is constructed out of two things. One has what is called a high spatial frequency meaning

there's a lot of edges and details that are very fine. The other has a sort of low spatial frequency

It's more blobs not a lot of edges and detail.

The amount of information you get from both of those depends on how close you are to the image. If you're near an image

its high spatial frequency the lines the contrast gives you a lot of information

But the big blobby vague shapes kind of just don't mean anything, but if you go far away

You lose your ability to really discern what you're getting from the fine details and the vague ones start to paint a more clear picture

You've probably seen an even more famous version of this that involves Albert

Einstein or does it? I'm gonna take my phone out turn on the camera and record a video

and show you what happens to Albert's face as I move away. I'm sure you've seen this one before but don't worry.

That was a photo. Here comes a video. Alright, so there's Albert, but now let's walk away and the first thing

we'll notice is Hannah say hello. Hey, wait a second where's Albert going

He's becoming Marilyn Monroe. Well actually the further

out I go, the more like Marilyn that's gonna look.

Let's see what happens if I zoom in. Ooohhhh it's Alberto again!

uhh that's not his name, Alberto.

But if I come in close

Einstein appears again. This works in the same way that the ghostly gaze illusion works.

Here's a slightly different version, but it's broken down the two images

We have a high spatial frequency image of Albert Einstein, which means lots of fine details edges high contrast

And then we have a very blobby

Soft not a lot of sharp detail image of Marilyn Monroe

Up close an image like this of Marilyn Monroe is hard to decipher.

It's hard to really figure out

but the detail in Albert Einstein's face is easy to see. As we move further away the fine details get lost we lose Albert and

the blobby vague shapes start to mean something to us and Marilyn emerges. Pretty awesome. Now

I've linked papers down below that explain this in more detail. A lot of this work has been pioneered by Aude Olivia.

I highly suggest reading those. Obviously what I love about Michael Bach's website is the fact that the illusions are?

Interactive. You've probably seen this ambiguous

Ballerina dancer before. The ambiguity lies in which direction she's rotating. Is she turning clockwise or counterclockwise

Well as soon as you look you your brain makes a guess and it's often hard to switch and see it from the other

perspective, but have a few friends come over and you might be surprised that they believe she's moving in a different way. This often leads

to arguments over what the figure is really doing

But Michael Bach's website allows you to more easily flip between both

directions of rotation by putting eyeballs on the figure. For instance right now

I think that she appears to be moving counterclockwise if seen from above so let me hit clockwise

Whoa now the eyes

help it reverse, and now she's moving clockwise from above for me. Very very cool, but now let's talk about

the Thatcher

Illusion. Right now you probably already think that the face looks a little bit weird

Well if you turn it upside down you'll see that it is actually

Really weird. When it faces upside down all of the cognitive tools. We have for analyzing how it looks and what it's doing well

they're not as great at doing their job, but enough about faces. Let's talk about color the

Exploratorium has a fantastic website full of interactive exhibits. This one I just discovered this morning actually

It's a fading dot illusion. You've got a green

Blob with a littler blue blob in the middle. Now

it's very important for this illusion to work that you stare at that blue dot

and don't move your eyes. Really just keep your eyes as still as possible and the blue dot will disappear

Until you move your eyes. The very second you move your eyes

it'll pop back into frame. Now some people find it easier to just look at the edge of the square keeping their eyes completely still

Until the blue goes away, but the second you move your eyes towards anything the blue dot appears

That's because when your eyes move

they collect new information and the blue dot which was kind of forgotten as being not important comes right back in because it is

now falling onto new cells in your retina. This illusion came from reddit, and I love it

We've got dots that are popping in and out of existence. The question is

do you and I I'm seriously asking you this do you think that the motion illusion

created here is of two dots going up and down or of two dots going side to side, or is it dots moving

Clockwise or counterclockwise. If you try really hard you can actually

flip your perspective just with your own will. Oh yeah I just did it. Now I'm seeing them going back and forth now

What's really interesting is that if you slow down

the frame rate of this animation it becomes even easier to flip between the different

perspectives. The creator of the gif luckily provided one the moves much slower and here I

Find it incredibly easy to choose exactly what I want the dots to be doing for me. When it's moving faster

I honestly cannot picture them moving in any kind of rotationally clockwise or counter clockwise

way, but when they're slow jeez I can just at will at the very moment I decide I want to see it see the motion

that I want to see. Now let's talk about hinged

tessellations.

A tessellation is a tiling of figures that can cover a plane indefinitely

But a hinged tessellation is one in which the actual tiles can rotate and lock back into a new position

So here is what I love about this site by Al Grant.

Not only do you learn about tilings and tessellations, but you also learn about how they can be

Hinged and there's even a hinged tessellation generator. I can choose between trapezoid and cyclic. Let's just do trapezoid well

let's do cyclic first. A cyclic quadrilateral is one whose points all lie on a circle

and I can choose where I put them. With a square the result is quite trivial

but you can choose all kinds of nutty shapes

and then once you're happy with what you've got go ahead and hinge them and look you have created a hinged

tessellation. Great job. Brilliant org made this episode possible, and I love them.

They are right in line with what Vsauce stands for: learning and

asking questions. On the site you can run through courses that quiz you and you might not get them all right.

I certainly don't but by getting questions wrong

I think you learn more, so let's just dive into the tessellations page. You can learn about them. Now here

we have a question : If extended to cover the plane which of the patterns below is a

regular tiling?

Very good. Well, I think

That I should have read all the information that came before this question

But I'm gonna go with D. Oh maybe it's all of them

Incorrect, but look what it says underneath incorrect. It's okay. Getting stumped is part of learning, and I totally agree!

That's what I love about brilliant.org. Also

we are offering a special deal the first 36 people to sign up to brilliant.org using the link below

Will get 20% off their annual

subscription so check that out. Thank you for supporting Vsauce. Thank you for supporting DONG and as always

thanks for watching