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Impossible Decision

An impossible decision on this Penrose Triangle…

The Penrose triangle, also known as the Penrose tribar, is an optical illusion that depicts a three-dimensional object that is physically impossible to construct.

The illusion is a two-dimensional drawing that is designed to create the impression of a triangular structure, but the angles of the lines are inconsistent with the laws of Euclidean geometry, making it impossible to construct in the real world.

How does the Penrose Triangle Illusion work?
Versions of the Penrose Triangle Illusion
Illusions like the Penrose Triangle Illusion
Discovery of the Penrose Triangle Illusion
References and Resources
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How does the Penrose Triangle Illusion work?

The Penrose triangle works by exploiting the way the brain interprets the 2-dimensional image of a triangular structure, but with impossible angles and lines that are inconsistent with the laws of Euclidean geometry.

These impossible angles and lines create a visual illusion of depth and three-dimensionality that is impossible to construct in the real world.

The illusion works by playing with the viewer’s expectations about the relationships between the lines and angles of the object and the viewer’s sense of depth.

The brain uses cues such as perspective, shading, and past experiences to create a 3-dimensional perception of the image.

However, in the case of the Penrose triangle, the brain is unable to reconcile the conflicting information, creating the illusion of an impossible object.

The Penrose triangle illusion also highlights the concept of “perceptual set” which refers to the brain’s ability to focus on specific aspects of the image and ignore others depending on the context.

The brain tends to focus on the lines and angles that suggest depth and three-dimensionality, while ignoring the impossible angles and lines that would make the object impossible to construct in the real world.

Additionally, the concept of “top-down processing” comes into play as the brain uses prior knowledge to interpret the visual information coming from the eyes, and tries to make sense of the image with the information it has.

The brain is unable to reconcile the conflicting information in the Penrose triangle, creating the illusion of an impossible object.

Versions of the Penrose Triangle Illusion

The following are some alternate versions of the Penrose Triangle Illusion:

Penrose Triangle clored — From Wikimedia Commons

Penrose Triangle rainbow GIF — From Wikimedia Commons

Illusions like the Penrose Triangle Illusion

Paradox illusions are a type of optical illusion that involve images that appear to be self-contradictory or impossible. They typically involve the manipulation of visual cues such as size, shape, movement, and depth perception to create an image that appears to be impossible or defies our understanding of the physical world.

In general, these illusions work by exploiting the way the visual system processes information. The brain relies on certain cues, such as perspective, shading, and texture, to infer the 3D structure of an object. When these cues are manipulated in a certain way, the brain can be fooled into perceiving an impossible or self-contradictory image.

Some related illusions include the following:

The Rubin vase, also known as the Rubin face or the figure-ground vase, is a famous optical illusion in which the image of a vase can also be perceived as two faces in profile looking at each other.

The duck-rabbit illusion is an optical illusion that is an image that can be perceived as either a duck or a rabbit depending on how the viewer looks at it.

The Necker cube is an optical illusion that features a simple wireframe drawing of a cube. The cube appears to switch back and forth between two different orientations.

The My Wife and My Mother-in-Law illusion is an optical illusion with an image of a young woman’s face that can also be perceived as an older woman’s face.

The Schröder Staircase is an optical illusion that features a drawing of a staircase. The staircase appears to be either ascending or descending, depending on how the brain interprets the angles of the lines.

Schroeders_stairs — From Wikimedia Commons

The impossible cube is an optical illusion that depicts a three-dimensional object that is physically impossible to construct.

The impossible trident is a three-pronged impossible shape resembling a trident. It is usually depicted as a three-pronged fork with each prong appearing to be a continuation of the next, creating an impossible shape.

The spinning dancer illusion is a visual illusion that depicts a silhouette of a dancer spinning clockwise or counterclockwise. The direction of the dancer’s spin can appear to change depending on the viewer’s perception

Spinning Dancer Gif — From Wikimedia Commons

The Monroe-Einstein illusion works by playing with the viewer’s expectations about the relationships between the features of the faces and the viewer’s sense of facial proportions.

Discovery of the Penrose Triangle Illusion

It was first created by the British mathematician and physicist Roger Penrose and his father Lionel Penrose, a psychiatrist and mathematician, in the 1950s.

Sir Roger Penrose is a renowned British mathematical physicist and Nobel laureate. He was born in 1931 and is still active today. He is known for his work in the fields of cosmology, general relativity, and quantum mechanics. He was awarded the Nobel Prize in Physics in 2020, jointly with Reinhard Genzel and Andrea Ghez, for his contributions to the understanding of the properties of black holes.

Penrose’s research has focused on the fundamental nature of space and time and the structure of the universe, he proposed new ways of understanding the Big Bang, black holes, and the nature of the universe itself. He has also been interested in the connection between physics and mathematics, particularly in the area of geometry. Penrose has written several books on these topics, which have been widely read and discussed by both scientists and the general public.

Penrose is also known for his work on the concept of “cosmic censorship” which is a theory that states that the singularities that occur in black holes are always hidden from the outside observer. He also developed new mathematical techniques, such as the Penrose diagram, which are used to describe the behavior of black holes and other singularities. Penrose is considered one of the most influential theoretical physicist of the 20th century and his work has had a significant impact on our understanding of the universe.

References and Resources

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How Many Black Dots?

How many black dots can you spot in this version of the scintillating grid illusion?

There are 12, but your brain will not let you see them all at once!

About the The Scintillating Grid Illusion

The scintillating grid illusion is also known as the “scintillating checkerboard illusion” and it is a variation of the Hermann grid illusion.

The scintillating grid illusion is caused by the way the visual system processes the edges of the lines forming the grid, creating the appearance of movement in the illusion.

Scintillating-Grid-New — From Wikimedia Commons

How does the Scintillating Grid Illusion work?
Versions of the Scintillating Grid Illusion
Illusions like the Scintillating Grid Illusion
Discovery of the Scintillating Grid Illusion
References and Resources
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How does the Scintillating Grid Illusion work?

The Scintillating Grid Illusion is an optical illusion in which a grid of light gray or white lines on a dark background appears to flicker or “scintillate.” The effect is most pronounced when the observer is looking directly at the intersection of the lines, and it is caused by the way the visual system processes the edges of the lines. The illusion is often used to demonstrate the neural processes that underlie visual perception, and it is related to other optical illusions such as the Hermann grid illusion and the Mach bands illusion.

The Scintillating Grid Illusion is believed to work by the way the brain processes the edges of the lines in the grid. The visual system is sensitive to the contrast between light and dark areas, and the edges of the lines in the grid create a high contrast between the light lines and the dark background. This high contrast causes the visual system to enhance the edges, creating the illusion of flickering or scintillating.

It’s also thought that the mechanism behind this illusion is related to the way the visual system deals with the ambiguous edges of the lines. In the intersection of the lines, the brain receives information that is not clear, and it tries to fill in the missing information by creating the illusion of movement.

Additionally, the illusion is more pronounced when the observer is looking directly at the intersection of the lines, as opposed to looking at the lines themselves. This is likely due to the fact that the visual system is more sensitive to edges that are oriented perpendicular to the line of sight.

Versions of the Scintillating Grid Illusion

The following is an alternate versions of the Scintillating Grid Illusion:

Illusions like the Scintillating Grid Illusion

Color illusions work by exploiting the way that the human visual system processes color and light. The human eye is able to detect light in the visible spectrum, which consists of different wavelengths of light that correspond to different colors. The brain then interprets this information to create our perception of color. However, the way the brain perceives color is not always a perfect representation of the physical reality.

There are several factors that can influence the way that the visual system processes color and light, which can lead to the perception of illusions. These factors include:

Contrast: The way that the brain perceives color can be influenced by the surrounding colors and patterns. High-contrast borders around an area of color can cause the brain to interpret the color as spreading or “bleeding” beyond the actual boundaries of the object.

Lighting conditions: The way that the brain perceives color can also be affected by the lighting conditions. For example, when an object is viewed in bright light, the eye’s color receptors may become fatigued, causing the brain to perceive colors differently than they actually are.

Color adaptation: The brain adapts to the colors that we see over time, which can influence the perception of color. For example, if an individual looks at a red object for an extended period of time, the brain will adapt to the red, and when that person looks at a white object, it will appear to have a pinkish hue.

Color constancy: The brain is able to adjust the perception of color based on the context in which it is viewed. This can create illusions where the same color appears to be different depending on the surrounding colors.

Shape use: Some illusions like the Hermann grid illusion or the Cafe Wall illusion, use specific patterns and shapes to manipulate the perception of color and shape.

Some related illusions include the following:

The Neon Color Spreading illusion refers to the visual phenomenon where an area of color appears to spread or “bleed” beyond its intended boundaries.

The Bezold Effect: This illusion is created by placing two or more colors next to each other, and the way they appear to change when they are close to one another.

The Mach Band Illusion: This illusion is created by the way the brain perceives edges of an object. When an object has a gradient of color, the edges of the object appear to be darker or lighter than they actually are.

Mach Bands Animation — From Wikimedia Commons

The Hermann Grid Illusion: This illusion is created by the way the brain perceives intersections of lines. When the intersections of a grid of lines are viewed, small gray dots appear at the intersections, even though they are not actually there.

The Watercolor Illusion: This illusion is created by the way the brain perceives edges of an object. When an object is surrounded by a colored halo, the object appears to have a different color than it actually does.

The Chevreul Illusion: This illusion is created by the way the brain perceives edges of an object. When the edges of an object are surrounded by a contrasting color, the edges appear to be a different color than they actually are. Chevreul’s illusion is similar to Mach bands, but they work in different ways. Chevreul’s illusion is an effect on the perception of hue, while Mach bands is an effect on the perception of brightness.

The Ishihara Illusion: This illusion is created by the way the brain perceives colors. When a color is surrounded by a contrasting color, the brain perceives the color to be different than it actually is.

Ishihara Plate 9 — From Wikimedia Commons

The flash lag illusion is a visual illusion that is based on the perception of the temporal relationship between a moving object and a flash of light. The illusion occurs when a moving object is followed by a sudden flash of light, and the perceived location of the flash appears to be behind the actual location of the object.

The Café Wall Illusion is a visual illusion that is created by a grid of alternating light and dark horizontal and vertical lines. The lines appear to be bent or tilted, even though they are actually straight.

Discovery of the Scintillating Grid Illusion

It was first described by an American psychologist, Edward H. Adelson in 1995.

Edward Adelson is a professor of vision science at the Massachusetts Institute of Technology (MIT) and a member of the MIT Media Lab.

He is known for his research in the field of computer vision, particularly his work on the perception of lightness and the “checkerboard illusion.”

He is also a recipient of the David Marr Prize, which is given by the International Association for Computer Vision to “outstanding young investigators” in the field of computer vision.

References and Resources

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Checkerboard Bulge

I love these cool checkerboard bulge illusions.

There are a few illusion types at play in here, but the effect is most similar to that of the famous Cafe Wall illusion.

A Few Other Checkerboard Bulge Examples

Table of Contents for the Cafe Wall (Base for Checkerboard Bulge)

How does the Café Wall work?
Versions of the Café Wall Illusion
Illusions like the Café Wall Illusion
Discovery of the Café Wall Illusion
References and Resources
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How does the Café Wall Illusion work?

The Cafe Wall Illusion works by creating the illusion of depth and perspective through the interaction of parallel lines and the edges of the squares in the checkerboard pattern. The parallel lines in the pattern create the illusion of rows of bricks that appear to be slanted, even though they are actually straight. The edges of the squares in the pattern also play a role in creating the illusion by creating the perception of shadows and highlights on the “bricks.”

The way the lines and edges interact with each other creates a conflict in the brain between the perception of the lines as straight and the perception of the rows as tilted. The brain resolves this conflict by interpreting the rows as slanted, which creates the illusion of depth and perspective. Additionally, the alternating light and dark rows also contribute to the illusion, as the brain perceives them as different depths of the wall.

The illusion is also affected by the viewer’s distance from the image, as the perceived tilt of the lines changes as the viewer moves closer or farther away. This is because the angle of the lines changes relative to the viewer’s perspective, which changes the way the lines and edges interact with each other.

Versions of the Café Wall Illusion

The following are some alternate versions of the Café Wall Illusion:

Cafe-Wall-Illusion-Building-Wikimedia-Source — From Wikimedia Commons

Cafe-Wall-Illusion-Original-Cafe-with-Richard-Gregory-Wikimedia-Source. — Original Cafe with-discoverer Richard Gregory from Wikimedia Commons

Cafe-Wall-Illusion-Purple-Yellow-and-Black

Illusions like the Café Wall Illusion

The following are some illusions similar to the Café Wall Illusion.

The Rotating Snakes is a peripheral drift illusion that consists of a grid of shapes, with some of them appearing to be rotating or undulating. The illusion is created by the interaction of the shapes with the neural processing of the visual system.

The Moiré pattern illusion: This illusion is created by superimposing two similar patterns on top of each other, such as a grid of lines or circles. The resulting pattern appears to be moving or changing.

The Scintillating Grid Illusion, in which a grid of black and white squares appears to pulsate or “breathe” when viewed from the periphery of the image.

The Zöllner illusion is a visual illusion in which parallel lines appear to be angled due to the presence of intersecting lines.

The illusion is often used to study the brain’s perception of shape and spatial relationships. It is considered one of the most powerful and striking examples of a geometrical-optical illusion. The perception of the illusion can be explained by the brain’s tendency to group lines together based on their similarity in direction and spacing, which can lead to an overestimation of the angle between the parallel lines.

The Müller-Lyer illusion: This illusion involves lines with arrowheads at the ends, which can make a line appear longer or shorter depending on the direction of the arrowheads.

The Poggendorff illusion is a visual illusion in which the brain perceives a diagonal line as being interrupted by an object, even though the line is actually continuous. The illusion is created by the misalignment of two parallel lines that are intersected by a third line at a certain angle.

Poggendorff illusion transparent gray bar

The Orbison illusion is an illusion of movement that is created when stationary, parallel lines are placed on a background of radiating lines. The parallel lines appear to be moving in the direction of the radiating lines, even though they are actually stationary. This illusion is thought to be caused by the interaction between the parallel lines and the radiating lines, which creates an illusion of movement in the brain.

The Wundt illusion is an optical illusion produces an inversed effect compared to the Hering Illusion. The vertical lines are both straight, but they may look as if they are curved inwards.

Discovery of the Café Wall Illusion

The Cafe Wall Illusion was first described by the British psychologist Richard Gregory in the 1970s.

Gregory was a cognitive psychologist who made significant contributions to the field of visual perception, including the discovery of the Cafe Wall Illusion.

He published his findings on the illusion in the journal “Nature” in 1973. Gregory was also known for his work on the perception of illusory contours and the perception of the Necker cube, which is another famous optical illusion.

References and Resources

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Fun Circles Illusory Motion

With Illusory motion, static image appears to be moving due to the interaction of color contrasts, shapes, and position.

How does Illusory Motion work?
Versions of Illusory Motion
Illusions like Illusory Motion
Discovery of Illusory Motion
References and Resources
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How does Illusory Motion work?

Illusory motion, also known as motion illusion, is the perception of movement in a static image or pattern.

This can occur when the brain is presented with a series of static images that change over time, or when certain visual patterns are arranged in a specific way.

The brain interprets these as if they are moving, even though the image or pattern itself is not actually moving.

There are several theories that try to explain the underlying mechanisms of illusory motion.

One theory is that it is a result of neural adaptation, where the visual system becomes adapted to certain stimuli and continues to respond as if they were present even after they are removed.

Another theory is that it is a result of the brain’s tendency to perceive patterns and to fill in missing information, known as Gestalt principles.

Versions of Illusory Motion

The following are some other examples of Illusory Motion

Peripheral drift illusion — From Wikimedia Commons

peripheral-drift-illusion-giving-a-throbbing-effect — From Wikimedia Commons

Peripheral_drift_illusion_blue-and-orange-wormhole

Illusions like Illusory Motion

The following are some illusions related to Illusory Motion

In Peripheral Drift illusions, the image or pattern appears to move or drift, even though it is actually stationary. This movement is caused by the brain’s attempt to interpret the image or pattern, which is often complex or ambiguous. The movement can be in any direction, such as horizontally, vertically, or diagonally.

Peripheral drift illusion jelly bean — From Wikimedia Commons

The rotating snakes is a peripheral drift illusion that consists of a grid of shapes, with some of them appearing to be rotating or undulating. The illusion is created by the interaction of the shapes with the neural processing of the visual system.

The Scintillating Grid Illusion, in which a grid of black and white squares appears to pulsate or “breathe” when viewed from the periphery of the image.

The Hermann Grid Illusion, in which the intersections of a white grid on a black background appear to be gray, even though they are actually the same color as the background.

The Zöllner Illusion, in which parallel lines appear to be tilted or bent when intersected by diagonal lines.

The Fraser Spiral Illusion, in which a pattern of short, curved lines appears to form a spiral.

These illusions are usually caused by the way our eyes process visual information and the way the brain interprets it. They can also be caused by the interaction of different visual elements, such as lines and angles, in the image. They are often used in research on visual perception and the neural basis of perception.

Discovery of the Illusory Motion

It is not clear who first discovered illusory motion. Some credit Aristotle in approximately 350 BC.

But these type of illusions have been observed and studied by various researchers over time, and many studies have contributed to the understanding of the phenomenon.

For example, peripheral drift illusions have been observed since the early 20th century and have been studied by various researchers in the field of visual perception, including scientists, psychologists, and neuroscientists.

Some of the early studies on peripheral drift illusions were conducted by the German physiologist Ernst Mach in the late 19th century, and later by the German psychologist Max Wertheimer in the early 20th century.

In the 20th century, several scientists and researchers have made significant contributions to the understanding of peripheral drift illusions and the underlying neural mechanisms, such as the American psychologist J.J. Gibson, the American neuroscientist David Hubel, and the British neuroscientist Melvyn Goodale.

References and Resources

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Motion Aftereffect – Starry Night

Van_Gogh_-_Starry_Night_-_Google_Art_Project.

The Motion Aftereffect (also known as the Waterfall Illusion) is a visual illusion experienced after viewing a moving visual stimulus, and then fixating on a stationary stimulus.

Here is an awesome example of this effect

Fixate on the moving image below for 30 seconds, then shift your gaze to The Starry Night and watch Vincent Van Gogh’s masterpiece come to life.

How does the Motion Aftereffect work?
Versions of the Motion Aftereffect Illusion
Illusions like the Motion Aftereffect Illusion
Discovery of the Motion Aftereffect Illusion
References and Resources
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How does the Motion Aftereffect work?

The motion aftereffect (MAE) is a visual illusion that occurs when one looks at a moving visual stimulus for an extended period of time, and then looks at a still object. The still object will appear to be moving in the opposite direction of the original stimulus. T

his effect is thought to occur because neurons in the visual system become adapted to the motion of the initial stimulus, and then continue to fire as if the motion were still present even when the stimulus is removed.

This causes the perceived motion of the still object.

MAE can occur with various type of motion such as rotation, translation, expansion and contraction.

Versions of the Motion Aftereffect

The following are some other examples of the Waterfall Illusion

Illusions like the Motion Aftereffect

The following are some illusions that are related to Motion Aftereffect

Motion-induced blindness (MIB) is an optical illusion that occurs when a stationary pattern or image is presented in the presence of a moving pattern or image. The stationary pattern or image appears to disappear or fade, even though it is still present, this phenomenon is called motion-induced blindness.

Motion-Induced-Blindness-Spinning-Table — Focus on the in the center of the table and the different objects disappear and reappear.

Motion-Induced-Blindness-spinning-squares-blue-dot-yellow-dot — Focus on the center dot and and the other dots disappear and reappear

Troxler’s fading, also known as Troxler’s effect, is a phenomenon in which a stationary visual stimulus eventually disappears from perception, even though it is still present in the visual field.

This occurs because the human visual system adapts to constant stimuli and eventually stops responding to them.

Lilac-Chaser_Troxlers Fading — From Wikimedia Commons
After staring at the cross for several seconds, the dots fade away

Troxler-Fading — From Wikimedia Commons
After staring at the cross for several seconds, colors fade away

Toxler-Fading-Blue-Circle-Red-Dot — From Wikimedia Commons
After staring at the dot for several seconds, the colored ring fades away

The Phi phenomenon is the illusion of movement created by the rapid succession of static images or light sources.

It is the perceptual phenomenon that explains how the human brain perceives motion when presented with a sequence of still images or light sources that are displayed in rapid succession.

Magni-phi-phenomonon. — From Wikimedia Commons

The Scintillating Grid Illusion, in which a grid of black and white squares appears to pulsate or “breathe” when viewed from the periphery of the image.

The Hermann Grid Illusion, in which the intersections of a white grid on a black background appear to be gray, even though they are actually the same color as the background.

The Zöllner Illusion, in which parallel lines appear to be tilted or bent when intersected by diagonal lines.

Discovery of the Motion Aftereffect

Some believe that The Motion Aftereffect effect was first observed and noted by Aristotle in approximately 350 BC.

More recently, the motion aftereffect was described by German physicist and physician Johann Christoph Friedrich von Schiller in 1812.

He observed that after looking at a rotating wheel for a period of time, stationary objects appeared to rotate in the opposite direction. He called this phenomenon the “spinning wheel illusion.”

However, the phenomenon was independently discovered by several other researchers in the 19th century including Peter Mark Roget and Charles Wheatstone.

About The Starry Night

The Starry Night is an oil painting created by Vincent van Gogh in 1889.

The painting depicts the view from the east-facing window of his asylum room at Saint-Paul-de-Mausole, just before sunrise, with the addition of an idealized village.

The work is one of the most recognizable in the history of Western culture and is considered to be among Van Gogh’s finest works.

The painting is characterized by its swirling, dynamic sky and the cypress tree at the center of the composition, which is a symbol of eternity and the unrelenting power of nature.

It is currently housed at the Museum of Modern Art in New York City.

References and Resources

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Cool Blue Cafe Wall Illusion

Cool Cafe Wall Illusion in Blue and Black

This cool blue Cafe Wall Illusion was created by Victoria Skye.

The parallel lines appear to be tilted or slanted, even though they are actually straight. For some, the effect in this version is even more pronounced than in the original Cafe Wall Illusion.

How does the Café Wall work?
Versions of the Café Wall Illusion
Illusions like the Café Wall Illusion
Discovery of the Café Wall Illusion
References and Resources
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How does the Café Wall Illusion work?

Versions of the Café Wall Illusion

The following are some alternate versions of the Café Wall Illusion:

Illusions like the Café Wall Illusion

The following are some illusions similar to the Café Wall Illusion.

The Scintillating Grid Illusion, in which a grid of black and white squares appears to pulsate or “breathe” when viewed from the periphery of the image.

The Zöllner illusion is a visual illusion in which parallel lines appear to be angled due to the presence of intersecting lines.

The Müller-Lyer illusion: This illusion involves lines with arrowheads at the ends, which can make a line appear longer or shorter depending on the direction of the arrowheads.

The Wundt illusion is an optical illusion produces an inversed effect compared to the Hering Illusion. The vertical lines are both straight, but they may look as if they are curved inwards.

Discovery of the Café Wall Illusion

The Cafe Wall Illusion was first described by the British psychologist Richard Gregory in the 1970s.

Gregory was a cognitive psychologist who made significant contributions to the field of visual perception, including the discovery of the Cafe Wall Illusion.

References and Resources

Check out our complete list of illusions.

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All The Balls are The Same Color

Seriously, all the balls are the same color. The brain interprets the color of the ball based on the surrounding colors and lines.

Zoom in for yourself to see…