Once a year, researchers who study the perception of visual information by the human brain allow themselves to be distracted from scientific work and take part in the Best Visual illusion of the Year competition. This is a competition where each of them can demonstrate in practice their discoveries. Here is a list of finalists and winners of the 2011 contest.

1 place. Disable color shift perception due to background movement

Description. If you look at a small white dot in the middle of the screen, then the change of colors of the surrounding elements is clearly visible. If the surrounding elements begin to rotate, the brain does not cope with the processing of information about the color change of each of them.


^{mp4 , webm , ogv , vimeo
Authors: Jordan Suchow, George Alvarez, Harvard University
Scientific work}

Other demonstrations of the same effect.
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2nd place. Contrast grouping

Description. The brightness level of four discs changes with time. The upper two brighten simultaneously, while the lower two darken simultaneously - and vice versa. On a contrasting background, it seems that the disks are grouped diagonally, but after replacing the background it can be seen that they are actually grouped horizontally.


^{Authors: Erica Dixon, Arthur Shapiro, Kai Hamburger, American University in Washington, University of Giessen (Germany)}

3rd place. Loch Ness aftereffect

Description. Concentrating on the red dot in the center, over time, it seems that the surrounding gray lines slowly rotate in one direction, and then quickly scroll in the opposite direction. Reverse rotation is an illusion, which is explained by the after-effect of slow rotation.


^{By Mark Wexler, University of Paris Descartes}
Better version with rotation settings.

Finalist. Face morphing

Description. If you follow the red dot, the change in facial features is barely perceptible. If the red dot disappears, it becomes obvious that the shape of the eyes, skin color and even sexual characteristics change in a person.


^{Authors: Rob van Lier, Arno Koning, Donders Institute (Netherlands)}

Finalist. Mask of love

Description. Considering this Venetian mask, many observers can not immediately understand that in fact it consists of an image of two people: a man and a woman kissing each other. When the brain recognizes two objects, it is able to stabilize on one or the other (the so-called “bistable illusion”).


^{Authors: Gianni Sarcone, Courtney Smith, Marie-Jo Waeber}
Source image