00:00Look at the center of the cross. No, do not let yourself be distracted by the glamour of the celebrities.
00:05Just keep fixing the cross. Keep going, just a little longer.
00:10And suddenly, something strange begins to happen.
00:14His faces go from superb red carpet to downright bizarre. Isn't it?
00:18What kind of disturbing spell works here?
00:21We promise you, we have not done any photoshop magic.
00:24Look, if we stop this crazy wheel and you focus on the photos,
00:28you will see that Miley Cyrus always looks superb.
00:31This optical illusion is known as the flash face distortion effect.
00:36Basically, these photos are arranged in such a way as to totally confuse our mind.
00:41And our brain loves to compare things.
00:43So, when the images scroll very quickly,
00:46and you see someone with a little nose just after someone with a normal nose,
00:50your brain is confused.
00:51Suddenly, a normal nose can look as huge as Pinocchio's.
00:56It goes the same for the eyes, the lips, everything you want.
00:59As our brain always compares each face to the one before,
01:03it ends up transforming these magnificent celebrities
01:06into exaggerated and frightening versions of cartoons of themselves.
01:11So, tell me, what do you see here? A horse or a seal?
01:15It depends partly on where your eyes are placed first.
01:18If you look at the bottom of the image, your brain probably thinks it's a horse.
01:23But if your gaze first goes to the upper right corner,
01:26suddenly it looks like the tail of a seal.
01:28But it's not just a matter of gaze.
01:30And something even stranger happens here.
01:33When our brain perceives an ambiguous figure with unclear information,
01:37we essentially see what we want to see.
01:40In an experiment, scientists showed this precise image to a group of people.
01:45And they were told that if they spotted a farm animal,
01:48they would get a treat.
01:49Yum!
01:50But if they saw a marine creature, they would get canned beans.
01:55Which is a bit strange, isn't it?
01:57The results showed that 80% of people saw a horse.
02:01So, they decided to change the rules.
02:04This time, anyone who spotted a marine animal would get a reward.
02:08When they changed the motivation, can you guess what happened?
02:12More participants ended up seeing a seal in the second round.
02:16So yes, it seems that psychology plays an important role
02:19in the way we interpret ambiguous images.
02:24We also have these undecipherable figures.
02:27I mean, no matter how much you try,
02:30you simply won't be able to fully understand the image.
02:33Take the impossible trident, for example.
02:35On one side, it looks like three cylindrical shapes,
02:38but on the other side, it looks like they merge into two rectangular parts.
02:43This happens because the center of vision of our brain
02:45does a lot of its work in a subconscious and automatic way,
02:49interpreting the figure as a three-dimensional object.
02:52But when we see this 3D structure,
02:54it simply doesn't make any rational sense.
02:57It's similar to Penrose's triangle.
02:59This triangle is physically impossible to build in the real world,
03:03so we simply can't understand it.
03:08The next optical illusion is the effect of negative remaining images.
03:12Look at the three dots on his nose.
03:14If you hadn't guessed,
03:16it's Jennifer Lopez looking like an avatar character.
03:19But don't worry,
03:20this strange aspect is about to change right in front of your eyes.
03:24Keep your eyes fixed on these three dots in the center of the image.
03:27Don't look away and don't blink.
03:31Okay, on the count of three, we'll switch to a white screen,
03:34but you have to keep your eyes wide open.
03:36Ready? Here we go.
03:38One, two, three, bam!
03:40Can you see what I see?
03:41Yes, it's J-Lo, gorgeous in her red outfit.
03:45Crazy, isn't it?
03:46But there's a solid reason behind this magic.
03:49Our eyes have millions of small light-sensitive cells
03:52called batons and cones.
03:54Batons help us see in low light
03:57and perceive things in peripheral vision,
04:00while cones are dedicated to color,
04:02bright light and fine details.
04:05When light hits these cells,
04:07they excite and send signals to our brains,
04:10where everything is processed to achieve what we really see.
04:13But here's the hiccup.
04:14Conic cells can get tired.
04:17If they fix the same color for too long,
04:19they need a break.
04:20That's when other conic cells intervene to help.
04:24The different cone cells are better
04:26at processing red, green and blue colors.
04:29So, when some cone cells get tired,
04:32the theory of color processing by opposition is triggered,
04:35allowing other cones to take over.
04:38And that's how the colors in J-Lo's photo magically appear.
04:44Hey, hey, look who it is!
04:46Einstein!
04:47Now, fold your eyes.
04:48Or, if you prefer, take a few steps back.
04:51Wait.
04:52Does Einstein suddenly turn into Marilyn Monroe?
04:55This is a hybrid image,
04:57which is like a mixture of two images.
04:59It combines the blurry parts of one image
05:01with the sharp details of another.
05:03In this case, Einstein's image is centered
05:06on fine lines and sharp contours,
05:08such as wrinkles or hair strands.
05:10While Marilyn Monroe's
05:12is more about the whole, with blurry shapes.
05:15When you look away or fold your eyes,
05:17these little details fade away,
05:19and suddenly, Monroe's face appears.
05:22The same thing happens here.
05:24At first, this woman seems a little ugly,
05:26neither happy nor sad.
05:28But if you fold your eyes a little,
05:30suddenly, she really looks angry.
05:32Oh, oh!
05:35Wow!
05:36What a turnaround!
05:38Here are photos of Kim Kardashian
05:40and Timothée Chalamet upside down.
05:42Have you noticed anything strange about them?
05:44You probably haven't,
05:46but if you look closely,
05:48you will see that their eyes and mouth are not inverted.
05:50This is called the illusion of the inverted face.
05:53This happens because our brains are programmed
05:55to recognize faces in place.
05:57We treat them like a whole
05:59and grasp the details very quickly.
06:01But when a face is upside down,
06:03our brains have trouble perceiving these strange details,
06:06like the lines upside down.
06:10This trick is known as
06:13And what's crazy is that these bricks
06:15are not inclined at all.
06:17In fact, the horizontal lines
06:19are perfectly straight and parallel.
06:21This image deceives our brain
06:23because of the way we treat contrast.
06:25The black and white squares
06:27placed next to each other
06:29create a visual conflict,
06:31leading our brain to think
06:33that these lines are curved.
06:35But if you change the colors for something softer,
06:37like pink and blue,
06:39the illusion disappears.
06:41This does not disturb our perception
06:43in the same way,
06:45so we can clearly see the straight lines.
06:47And there is something else.
06:49Look at the layers of mortar between the bricks.
06:51Yes, these gray lines.
06:53The distortion only occurs
06:55when the brightness of the mortar
06:57is between the dark and light squares.
06:59So, if the mortar is too dark or too light,
07:01the illusion disappears.
07:05These strawberries are red, aren't they?
07:07False.
07:09The strawberries are not red at all.
07:11They are gray.
07:13This magic occurs
07:15due to something called color constancy,
07:17which is our ability to recognize
07:19the color of an object
07:21regardless of lighting changes
07:23or environment.
07:25In this experiment,
07:27all the red pixels in this photo
07:29have been replaced by gray pixels,
07:31and we can prove it by zooming.
07:33We feel like there is red in this image
07:35only because the background is blue.
07:37Then, it determines the color
07:39of the objects by compensating
07:41the color of the light source.
07:43When your brain takes these gray pixels
07:45and subtracts this blue bias,
07:47you end up seeing red.
07:49Interesting, isn't it?
07:51The same thing happens with the dress.
07:53If your brain perceives the lighting
07:55as a little yellowish,
07:57it tries to compensate for this golden glow
07:59by showing you the dress in blue and black.
08:01But if your mind thinks
08:03that the background is darker,
08:05and suddenly, the dress appears
08:07white and golden.
08:09So, what is the real color of the dress?
08:11Well, in this case,
08:13it is actually black and blue.
08:15But let's finish this
08:17before diving into this endless debate.
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