The Rabbit Duck
Do you notice the rabbit first, or the duck? This image originally appeared in a German humor magazine in 1892, reportedly inspiring some profound philosophical thoughts from Ludwig Wittgenstein.
Hering Illusion
The Hering Illusion is an optical illusion discovered by German physiologist Ewald Hering in 1861. Both vertical lines are straight, despite the appearance that they are bowed outward. The distortion is created by the pattern of lines in the background, simulating a false perspective of depth.
Optical illusions teach us about visual perception and its limitations. These illusions are specifically designed to trick the human brain. Things aren’t always how they appear… can you handle these dizzying illusions?
Impossible Trident
An impossible trident, also known as an impossible fork, blivet, devil’s tuning fork, etc., is an impossible object that appears to have three cylindrical prongs, which mysteriously transform into two rectangular prongs at the other end. The impossible fork made its debut on the cover of MAD magazine in March 1965.
Cafe Wall Illusion
This illusion was titled after Dr. Richard Gregory observed the pattern on the wall of a Bristol cafe in 1973. The alternating light and dark “bricks” are staggered between straight dividing lines, which appear to be sloped, but are actually parallel. It was first named the Kindergarten illusion in 1898.
Chubb Illusion
The Chubb illusion occurs when the contrast of an object varies based on its relative contrast against the field on which it is displayed. This error in visual perception was discovered by Charles Chubb and colleagues in 1989. Even though the circles depicted here are identical, one seems to have a higher contrast than the other.
Bezold Effect
Does the red on the left look lighter than the red on the right? German meteorologist Wilhelm von Bezold discovered an effect that shows how color can appear lighter or darker depending on its relation to adjacent colors. The red on both sides is actually the same.
Magic Eye Illusion
This optical illusion requires a bit more attention. Get close to the image, unfocus your eyes, and refocus them as if you were looking beyond the image. A three-dimensional illusion, also known as an autostereogram, should appear.
Ebbinghaus Illusion
Although it may seem like the orange circle on the right is larger than the one of the left, both circles are the same exact size. In an Ebbinghaus illusion, the space surrounding an object deceives the eye, altering our visual perception of size and space.
Columns or People?
Which do you see? The stair banister illusion depicts obvious columns, but in the negative space, you can make out the silhouettes of people. This is called a double image. Sometimes, double images are drawn two-dimensionally, making it even more difficult to decipher.
Impossible Elephant
This drawing, aptly titled “L’egs-isential Quandary,” was created by scientist Roger N. Shepard. The elephant is based on a dream he had in 1974. Similarly to the aforementioned trident, this illusion is an example of the impossible image, in which the artist intentionally confuses the viewer between the figure and the background.
Hermann Grid Illusion
The Hermann grid illusion is one of the most common types of illusions, characterized by “ghostlike” gray blobs perceived between intersections of a white or grid on a black background. The gray blobs disappear if you look directly at the intersection.
Fraser Spiral Illusion
Discovered by psychologist Sir James Fraser in 1908, this optical illusion tricks the brain into thinking that the black and white lines are spiraling inward. However, if you trace one individual line, it becomes obvious that the image is made of concentric circles rather than a spiral.
Illogical Cube
The “impossible cube” or “illogical cube” is an ambiguous object that makes the viewer believe they are seeing a three-dimensional object, when in reality, the object is two-dimensional. The illogical cube was invented by famous artist and printmaker M.C. Escher, who is known for many other illusions, such as the infinite Penrose staircase.
Kanisza Triangle
In 1955, Italian psychologist Gaetano Kanizsa created a classic example of illusory contours: the Kanizsa Triangle. The above image forces the eye to perceive a white equilateral triangle even though there are no explicit lines to indicate such. Our eyes naturally try to find suggestions of shapes that aren’t really there.
Floating Leaves
The purple “leaves” in this image appear to be moving against the green background, but the movement is just a result of heavily contrasting colors. If you stop and stare at individual leaves, the image should remain still.
Land or Sea?
This is a double-image painting by Canadian artist Rob Gonsalves, who also painted dozens of other double-image works. The bridge slowly fades away into the sky as the clouds form the sails of a ship.
Lilac Chaser
The lilac chaser illusion, also known as the Pac-Man illusion, consists of 12 blurred lilac dots arranged like numbers on a clock with a black cross in the center. Each dot is blocked out for 0.1 seconds in a clockwise rotation. If you stare at the black cross, the absent dot appears to be replaced with a green dot.
Liar Face
Upon first glance, this is simply a drawing of a man’s face looking to the left. Can you find the word that composes this image? If you look at the portrait sideways, the face disappears, leaving the word “Liar” in its place.
Warped Chair
This chair appears to have a classic silhouette… until the man sits down. It’s actually a custom-made piece of furniture, designed by French studio Ibride to fool the eye. The chair’s left side slopes downward and the seat is deliberately uneven. When perceived from the correct angle, the chair transforms into an optical illusion.
The Muller-Lyer Illusion
The Muller-Lyer Illusion was created in 1889 by Franz Carl Muller-Lyer, a French sociologist. The illusion consists of three stylized arrows. Although they all appear to be different sizes, all the lines are actually the same length.
Vertical-Horizontal Illusion
The vertical-horizontal illusion is the tendency for viewers to overestimate the length of a vertical line when compared with a horizontal line of the same length.
Filling-in Phenomenon
The filling-in phenomenon is responsible for the completion of missing information across a physiological blind spot. When fixating steadily on the central dot for many seconds, the peripheral outline will fade and be replaced by the color of the background.
Color Constancy
Color constancy is a feature of human color perception, ensuring the perceived color of objects remains relatively consistent regardless of varying illumination. For instance, a green apple looks green to us at midday beneath white sunlight, and also at sunset when the sun is red. This helps us to identify objects.
Penrose Stairs
The Penrose stairs, or Penrose steps, is also known as the impossible staircase. It is an impossible object created by Lionel Penrose and his son Roger Penrose in which a two-dimensional staircase makes four 90-degree turns as it ascends or descends on a continuous loop. This way, a person could climb them forever and never get any higher.
Isometric Illusion
An isometric illusion, also called an “ambiguous figure” or “inside/outside illusion,” is an image in which the shape can be perceived as either an inside or an outside corner.
Trompe-l'oeil
Trompe-l’oeil is French for “deceive the eye.” It is an art technique that uses realistic imagery to create an optical illusion that the object exists in three dimensions.
Wagon-Wheel Effect
The wagon-wheel effect, also known as the stagecoach-wheel effect or stroboscopic effect, is an optical illusion in which a spoked wheel appears to rotate differently from its actual rotation. The wheel can appear to rotate slower than its actual rotation, remain stationary, or rotate the opposite direction of ist true rotation.
The Disappearing Model
Disappearing Model is a trompe-l'oeil body painting by Joanne Gair. It is part of the highest-rated episode of Ripley’s Believe It or Not! Gair was noted for her ability to “make people disappear by painting them right into a background or paint clothing on a human body that is virtually indistinguishable from actual fabric.”
Jastrow Illusion
The Jastrow illusion was discovered by American psychologist Joseph Jastrow in 1889. In the above illustration, the two figures are identical, even though one appears to be larger than the other.
Motion Illusion
The motion illusion effect is an optical illusion in which a static image appears to be moving due to the cognitive effects of contrasting colors and the specific arrangement of shapes.
Mach Bands
Mach bands is an optical illusion named after physicist Ernst Mach in which the exaggerated contrast between slightly different shades of gray triggers edge-detection in the human visual system.
Thaumatrope
A thaumatrope is an optical toy that became popular in the 19th century. A disk with a picture on each side is attached to two pieces of string. By twirling the strings quickly between one’s fingers, two pictures appear to blend into one.
Peripheral Drift Illusion
The peripheral drift illusion is a motion illusion created by the presence of sawtooth luminance. It is caused by the brain’s interpretation of patterns seen outside the eye’s area of focus.
Penrose Triangle
The Penrose triangle was created by Swedish artist Oscar Reutersvärd in 1934. It was described and later popularized by mathematician Roger Penrose, who described it as “impossibility in its purest form.”
Orbison Illusion
The Orbison illusion is an optical illusion first founded by psychologist William Orbison in 1939. The rectangle and inner square both appear to be distorted against the radiating lines.
Adelson’s Checker Shadow Illusion
The image features a black-and-white checkerboard with a green cylinder on top of it, casting a diagonal shadow across the board. The black and white squares A and B are actually the same shade of gray.
Necker Cube
The Necker cube is an ambiguous line drawing. The image appears to be a wire-frame drawing of a cube in isometric perspective, but when the parallel lines cross, it’s unclear which side is in front or behind. This allows for two interpretations of the cube. If you stare at the picture, it seems to flip back and forth.
Poggendorff Illusion
The Poggendorff Illusion involves the perception of diagonal lines interacting with horizontal and vertical edges. The image features a straight black line which appears to be connected to a blue line, obscured by a gray rectangle. In reality, the red line is connected to the black line, rather than the blue one.
Zöllner Illusion
In this image, the black lines appear not to run parallel to one another, but that’s not the case. The shorter lines are angled against the longer lines, creating the impression of depth.
White’s Illusion
White’s illusion is a brightness illusion where stripes of black are white are partially replaced by a gray rectangle. Both the gray bars of A and B are the same color and opacity, but the brightness of the gray segments appear to be different based on the background.
Troxler’s Effect
If you stare at the blurry image above without blinking, what do you see? Does it begin to fade away? This is a visual phenomenon called the Troxler Effect, discovered in 1804 by Swiss physician Ignaz Paul Vital. It reveals how the human sensory system adapts to visual stimuli.
Shepard’s Table
Remember the impossible elephant? Roger Shepard’s Mind Sights (1990) features this simple yet confusing visual illusion, in which these two tables appear very different, but are actually identical. The perceptual error is caused by our brain’s desire to make a 3D interpretation of 2D images.
Afterimage Illusion
The afterimage, or “ghost image,” is an optical illusion in which an image appears in one’s vision after exposure to the original image has stopped.
Rubin Vase
A Rubin vase is an ambiguous or bistable (reversing) two-dimensional image. The famous set of forms were developed around 1915 by Danish psychologist Edgar Rubin.
Hybrid Image
A Hybrid image is an optical illusion developed at MIT. This illusion occurs when an image can be interpreted in two different ways depending on its distance from the viewer.
Forced Perspective
Forced perspective is employed in both film and architecture to create the illusion that an object is farther away, closer, larger or smaller than it really is. Visual perception can be manipulated through the correlation between scaled objects and the vantage point of a person or camera.
Waterfall
M.C. Escher’s lithograph Waterfall was first printed in October 1961. The image depicts a perpetual motion machine where water from the base of the waterfall appears to run downhill along a path before reaching the top of the waterfall.
Sander Illusion
The Sander illusion, also known as Sander’s parallelogram, is an optical illusion in which diagonal line bisecting the larger parallelogram on the left appears to be longer than the diagonal line bisecting the smaller parallelogram on the right. However, both lines are the same length.
The Missing Square Puzzle
The missing square puzzle is an optical illusion that can be used in mathematics classes in order to help express reasoning about geometrical figures.
The McCollough Effect
This illusion is a visual phenomenon in which the colorless gratings appear to be colored depending on their orientation.
Cornsweet Illusion
The Cornsweet illusion occurs when two colors appear different when placed directly next to one another, but when the colors are separated by a black line, they look identical.
Barberpole Illusion
The barber pole illusion reveals biases in the processing of visual motion in the human brain. It transpires when a diagonally-striped pole is rotated around its vertical axis, making it look like the stripes are moving in the direction of the vertical axis rather than around it.
Ehrenstein Illusion
This is an optical illusion in which the sides of a square take on a curved shape when placed inside a pattern of concentric circles. The illusion was studied by German psychologist Walter Ehrenstein.
Ames Room Illusion
The Ames room, invented by American scientist Adelbert Ames, Jr. in 1946, is a distorted room that is used to create an optical illusion. It is viewed with one eye through a peephole.
Ames Trapezoid Window
The Ames trapezoid window appears to be a rectangular window but is actually a trapezoid. The cardboard has the same image on both sides and is hung from a wire or attached to a rotating axis so it can rotate around continuously.
Ponzo Illusion
The Ponzo illusion is a geometrical illusion first demonstrated by Italian psychologist Mario Ponzo in 1911. He hypothesized that the human mind judges an object’s size based on its background, demonstrating the suggestion by drawing two identical lines across a pair of converging lines.
Motion Silencing Illusion
Motion silencing is a visual phenomenon in which rapidly changing objects appear to stop changing with motion. The illusion was first described by Jordan Suchow and George Alvarez in an article they published on the topic.
Lunar Terminator Illusion
A lunar terminator tilt illusion occurs when an observer on Earth wrongly expects that the direction of sunlight illuminating the moon will correspond with the position of the sun. However, it does not appear to do so due to the slope of a slight ray changing across the sky.
Fechner Color
The Fechner color effect is an illusion of color that can be seen when looking at certain changing or moving black-and-white patterns. The effect is most commonly demonstrated with Benham’s top.
Hollow-Face Illusion
The Hollow-Face illusion is an optical illusion in which a concave face is perceived as a normal convex face. The illusion is also known as a Hollow-Mask illusion.