1 The rubber hand illusion
Incredibly, it is possible to make someone believe that a fake hand is their real hand. This effect is achieved by tapping synchronously on a fake hand and a real hand. Some people feel the illusion with such intensity that if a dangerous stimulus threatens the false hand, they become frightened, believing that it is going to hurt them.
2 Thatcher Effect
This effect is achieved by turning the mouth and eyes in someone’s photograph. If you place this image upside down you will barely notice that the eyes and mouth are inverted, however if you place the image right side up you will be horrified to see the face. Thompson was the first to discover this effect, which is called the “Thatcher Effect” because he observed it using a photograph of the former British minister.
3 The Illusion of the Thermal Grill
The title of this illusion is a direct translation from English, and refers to the original procedure to achieve it (you have to use metal grates). However, we can experience it in our own home. Take two glasses, fill one with hot water (about 40º), and the other with cold or room temperature water. Place your index and ring fingers in the hot water, and your middle finger in cold water. You will immediately feel a painful sensation of heat in your middle finger, curiously the one that is immersed in cold water.
4 Einstein-Monroe effect
This effect, designed by Aude Oliva, professor in the Department of Brain and Cognitive Sciences at MIT, was devised with the purpose of creating a test that would easily detect myopia problems. If you don’t have vision problems, at first you will see the image of the Nobel Prize in Physics, but if you move away from the screen and squint you will see one of the sexiest women in history. On the other hand, if you wear glasses or contact lenses, in principle you will also see Einstein, although if you take them off you will see Marilyn’s face. Therefore, if you think that you do not have vision problems and you see the image of Marilyn even from close up, I recommend that you get a check-up at the eye doctor.
5 Bouba-Kiki Effect
This effect is not an illusion in itself, it is a pattern observed in more than 90% of the population. If I asked you which one was called “bouba” and which one was called “kiki,” which figure would you give each name to? Most people would say the one on the left is kiki and the one on the right is bouba. This curious phenomenon occurs due to what is known as synesthesia, by which your brain is able to integrate different sensory inputs (in this case auditory and visual) into a single perception. The effect has been observed even in babies, so it could be an innate property to relate sounds and shapes.
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6 The chess board
The perception of colors, tonality and brightness is something extremely relative. The brain not only looks at the wavelength emitted by a certain stimulus to interpret color, it also takes into account the wavelength of those stimuli that surround it. The perfect example to illustrate this circumstance is that of the chess board. Apparently grid A is darker than grid B, although they are actually the same color. Why is this happening? Grid B is surrounded by black squares so it is perceived lighter, while grid A is surrounded by lighter stimuli so it is perceived darker.
7 Illusion the twinkling grid
If you look at the grid you will see a series of spots that appear and disappear. When you look directly at the intersection of the grid the black spot disappears, while with peripheral vision you can see dozens of spots at each intersection. The illusion was discovered by Hermann back in 1870.
8 Pinocchio’s Nose Illusion
The Pinocchio illusion is achieved by covering someone’s eyes. Later, another person sits in front of the one whose eyes are covered, and the latter touches his nose with one hand while touching the nose of the person sitting in front with the other hand. This experiment generates the sensation that the nose is longer than it really is.
9 McGurck Effect
When faced with the same sound we can have a different perception depending on what we are seeing. This phenomenon is called the McGurck effect. By watching the video you can understand why it happens.
10 Dysmorphopsia
If you have studied psychopathology you will know that dysmorphopsia is an alteration in the perception of the shape of objects. It is common in some mental pathologies, although it can be generated artificially. Don’t worry, the effect lasts about ten seconds, it is not permanent. When you open the video, stare at the center of the screen and when the video ends, look anywhere around you. What do you think will happen?
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