00:00This optical illusion will allow you to know if you are able to drive in the rain or not.
00:06Take a look at this image.
00:08Try to locate the hidden number sequence inside.
00:11Let's go!
00:19Did you say...
00:203, 4, 152, 839?
00:23If this is the case, then your sensitivity to contrast is impeccable.
00:28This famous sensitivity to contrast helps you to clearly distinguish the outline of small objects.
00:33If this function is not well developed at home,
00:36then you should probably not drive in the rain or even when there is fog.
00:43Look at this image.
00:44What animal is not represented here?
00:46A rabbit, a duck or a snail?
00:57The image clearly does not represent a snail.
01:00Well done if you found the right answer.
01:03The image clearly does not represent a snail.
01:06The image clearly does not represent a snail.
01:10Well done if you found the right answer.
01:17How many different scenes can you spot on this image?
01:203, 4, try to guess.
01:29There are only two.
01:30You should be able to see a chalice in the first scene.
01:33And then, when you change your point of view,
01:36you should be able to spot two profile faces on a white background.
01:44Okay, take a look at these two images.
01:47Can you tell if the red circle on the right is bigger than the one on the left?
01:58Believe it or not, these two circles are actually exactly the same size.
02:03This illusion is known as the Ebbinghaus illusion
02:06and was discovered by a German philosopher at the beginning of the 20th century.
02:12One of the possible explanations for which our brain derails
02:15when it contemplates this image is due to the size of the circles around it.
02:20As the ones on the right are much larger,
02:22it gives the impression that the red circle on the right is much smaller than the one on the left.
02:26Can you spot the eye of this parakeet for 15 seconds?
02:29Just keep looking at it.
02:31We'll tell you when you can close your eyes.
02:33You are about to see a perfect example of a remaining image.
02:373, 2, 1 and close your eyes.
02:40Can you see a red parakeet?
02:56Can you see a red parakeet?
03:04Isn't it incredible that, although this parakeet is black and white,
03:09you have the impression of seeing the color red?
03:12Once again, it's just your brain trying to guess the color of something.
03:20Behind all these little black dots is a hidden image.
03:23Are you one of the 1% of the population who are able to see it?
03:34It's a minion. Congratulations if you spotted it.
03:40Here's another one in the same style.
03:42Can you spot what's hidden here?
03:44Here.
03:51It's a ninja turtle.
03:53Honestly, you had to be a bit of a ninja yourself to spot it.
04:00And this one?
04:08Well, well, it's Homer Simpson.
04:14Now, something is hidden behind these black stripes.
04:17How does your X-ray vision work?
04:26You just saw if you understood that it was the eponymous hero of the movie Dragon.
04:31It's cute.
04:35Are you able to say which circle in this image is the darkest?
04:45Oh, oh, it was really a trick question.
04:47All circles are exactly the same color.
04:50It's a classic example of the optical illusion of saturation.
04:54It shows how our brain perceives color in a very subjective way.
04:58The lighting and the background of an object actually influence the way we see it.
05:03Thus, when the gray circle is on a darker background,
05:06we tend to believe that it is lighter than its true color.
05:10And vice versa.
05:14This illusion is called the impossible triangle.
05:17But wait, what makes it so impossible?
05:20You only have a few seconds to try to understand it.
05:30The tripod, or pink triangle, is also known as an impossible object
05:35that simply cannot exist in reality.
05:38This magical triangle defies the laws of Euclidean geometry.
05:42If you follow a ball sliding on the surface of the triangle from its highest point,
05:47you will notice something strange.
05:50It seems that the left side of the triangle moves away from the viewer,
05:53while the right side moves closer to you.
05:56The pink triangle is the type of geometric figure that can only exist as an optical illusion,
06:02because...
06:03Here's what it looks like if we dissect it.
06:06We're pretty far from a triangle, aren't we?
06:12Look at this image.
06:14In your opinion, which line extends the black line?
06:17The red line or the blue line?
06:26As surprising as it may seem,
06:28it is not the blue line, but the red line.
06:31This illusion was first imagined in the 1860s
06:35and is called the Poggendorf illusion.
06:38It is a classic example of how our brain perceives geometric shapes and depth.
06:43According to scientists, our brain tries to apprehend these images in two dimensions
06:48with three-dimensional properties.
06:50That's why it alters the depth between the lines in this image.
06:54It's pretty amazing, isn't it?
06:58Look carefully at this staircase.
07:00And now, let's turn the image upside down.
07:02It still looks like a staircase,
07:04but instead of going from right to left, it looks like it goes from left to right.
07:07Don't blink, though.
07:09Because if you do, the illusion will disappear
07:12and you will find yourself with the original image.
07:21This illusion is known as Schröder's staircase
07:24and was invented by the German naturalist Heinrich Schröder in 1858.
07:29It is extremely simple,
07:31but it relies on the same principle that we saw in the previous illusion.
07:35If we dismantle this staircase,
07:37we will notice that the image is actually flat.
07:40What our brain perceives as a three-dimensional image
07:43is only a combination of shadows and light.
07:46This means that 3D itself is an optical illusion.
07:51It operates because our brain receives images
07:54and tries to adapt them to those it already knows.
07:57It sees a shadow in a two-dimensional image
08:00and interprets it as depth.
08:02Basically, it creates an artificial perspective of the object in front of us.
08:07In this case, this is what we call a three-dimensional perspective.
08:15These circles seem to turn on themselves very quickly.
08:19Do you think they move for real,
08:21or could we say that they are motionless?
08:25I know it's hard to believe,
08:27but they don't move an inch.
08:29This illusion has disconcerted netizens,
08:31but this is what happens behind the scenes.
08:34There is an inner edge
08:36and an outer edge very, very thin to these circles.
08:39And these edges are of a different color from the rest of the circle.
08:43To create this illusion,
08:45the animators move these outer edges.
08:48The animators move these outer edges.
08:51The animators move these outer edges.
08:54But because of the color variation,
08:56our brain interprets it as if the entire circle were moving.
09:00That's why even if we block the arrows,
09:02we still have the impression that the circles are moving.
09:08Look at this image.
09:09It looks like the square in the middle is breathing, doesn't it?
09:12As if it was growing before shrinking.
09:15And what if we told you that it simply turns on itself,
09:18but doesn't change its size?
09:21Here's what happens.
09:23This illusion is based on a principle called motion binding.
09:26It occurs when our brain tries to predict
09:28the movement of one of the elements in the image.
09:31It's breathtaking, isn't it?
09:36Let's try another one.
09:38Fix the cross in the middle of this image for 10 seconds,
09:41from now on.
09:44All the colors of the image have they disappeared
09:46without letting you see anything but a white page?
09:49Strangely, our brain simply erases all the nuanced colors
09:53and leaves you with this white screen.
09:57First of all, we have to think about
09:59how we can predict the movement of the elements in the image.
10:02How can we predict the movement of the elements in the image?
10:05How can we predict the movement of the elements in the image?
10:08How can we predict the movement of the elements in the image?
10:12First of all, we have what looks like a gray bar
10:15moving from top to bottom on an orange background.
10:18But if you fix this little black dot at the bottom right,
10:21you could see the gray bar take on a different color.
10:25What color did you see?
10:32Did you say blue?
10:34Yes, that's exactly it.
10:37Here is the drawing of a city with a dot in the middle.
10:40Fix this dot for about 10 seconds, from now on.
10:56Wow, but what just happened?
10:58Even after the image turns black and white,
11:01our brain is still able to perceive the opposite colors.
11:05This is another example of remanence.
11:08Once we have fed our brain with a fixed image of something,
11:12when we turn it black and white,
11:14our brain is still trying to guess the colors.
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