Should you trust your eyes? 5 Optical Illusions That Will Trick Your Brain

[00:00:00]We are used to seeing animation on smartphone screens and monitors, but how is this possible on a regular piece of paper? When I move the black stripes over this strange picture, it literally comes to life right before your eyes.

[00:00:12]How does it work? Imagine looking at a cat through a fence, but you don't see the whole cat. What if it's not a cat hidden behind the bars at all? Like a dog for instance. Of course, this is a joke, but it perfectly shows that anything can be hidden behind the bars.

[00:00:27]In this picture, I encoded three movements of the cat. Through the semi-transparent bars, you can clearly see that they hide two modified frames.

[00:00:36]And when the fence moves, the gaps in it always reveal only one frame at a time.

[00:00:41]This optical effect is called barrier grid animation. Look how incredibly realistic the movements look with six encoded frames, especially with a black drawing and black stripes. [music] But the most interesting part is that you can make this animation not only with straight lines. Here is an example where the stripes are actually printed as waves.

[00:01:01]At the same time, the bird's movements are hidden in the same wavy lines. In this example, the same principle is used, but the colors and the images themselves change. By the way, you can make the same illusion with a circular grid. You can create this variety of options yourself [music] using a single program. You can find the link to it, as well as more examples of barrier grid animation, in the description below the video. But for now, let's move on to something sweet. Here are three donuts with different frosting: white vanilla, pink strawberry, and brown chocolate.

[00:01:33]Let's open this box, and inside, it's maple donut. We open the box on the right, and there it is, maple again. And what is in the box in the middle? It's maple here, too. That is how the colored stripes on top and the colored sheets under the donuts make us perceive the same color so differently.

[00:01:51]In the picture, you see two seagulls of different colors, but there is a third bird here. What, you don't see it? Here it is. It turns out that its color is the same as the bird on top. But let's move it to the bottom and it looks exactly the same as the bird at the bottom. It turns out our vision tricked us. All three of these birds are the exact same color.

[00:02:13]And here is a frog sitting in the center of the plate. Let me try to catch it.

[00:02:17]Stop. But why can't I grab it? And actually, there is a hole here, not a frog. This optical illusion is possible thanks to the specific reflection [music] features in two curved concave mirrors. In reality, the frog is actually lying inside and facing the other way.

[00:02:35]And here, you probably thought the blue one was on top or maybe the yellow one or the green one. Well, it was actually the red one.

[00:02:43]>> [music] >> And which pencils are on top here? It seems like this is impossible. In reality, these two pencils were lying on top of the others. But what is the secret of this illusion? The key is in the special surface of this piece of plastic, which is called a Loubor lens.

[00:02:58]If you look closely at the edge, you will see that the entire surface is covered with tiny semi-circular ridges, just like this larger curved lens.

[00:03:06]If you pass a laser beam through this curved lens, the light refracts. The path it takes to reach the wall changes depending on the angle it enters and exits the acrylic. If you overlay this effect several times at different points on the curved surface, >> [music] >> you can see that the lasers first converge at one point and then scatter further. This is the main thing to understand about these transparent ridges. They cause the incident light to expand in the direction the ridges themselves are facing.

[00:03:34]>> [music] >> For a single point of light, it works like this. The point is simply stretched into a stripe [music] when it passes through the ridges in the plastic. When I rotate the card, the stripe rotates, too, because it stretches only perpendicular to the ridges.

[00:03:48]But now let's look at it with a stretched laser beam. If the ridges on the lens are perpendicular to the line, almost nothing will happen to the laser line. You are simply stretching this line even further in the same direction.

[00:04:01]It works exactly the same way with a long narrow object like this pencil when it is stretched along its own axis. It still looks like a pencil. It just appears longer and the small details on it are erased due to the stretching. But if we change the direction of the louvre lens so that it stretches the light horizontally, the vertical laser line will change beyond recognition. It will become much wider and due to the scattering of light >> [music] >> much dimmer. The same thing happens with the pencil. At the right distance, it stretches in width so much that its color fades. In the end, it practically dissolves into thin air and becomes invisible. [music] Usually, when you stack pencils on top of each other, it is immediately clear which one is on top because it simply overlaps the rest. [music] But here, the lens stretches the color of the top pencil along its length, visually closing all the gaps. And since the other pencils lie at different angles, their image is stretched so much that they completely disappear from view.

[00:04:57]And now, click on the picture in the center of the screen to watch more incredible optical illusions. See you in the next video.