Geometric Illusions

Circle Spiral Illusion

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Circle Spiral Illusion

This Circle Spiral Illusion is a version of the the “Fraser Spiral Illusion” or “False Spiral Illusion.” In this illusion, a series of concentric circles, when arranged in a particular pattern, appear to form a spiral or twisting pattern, even though the individual circles are actually concentric and not spirals.

Circle Spiral Illusion


Table of Contents

What is the Circle Spiral Illusion?

The Circle Spiral Illusions is a version of the “Fraser Spiral Illusion” or “False Spiral Illusion.” In this illusion, a series of concentric circles, when arranged in a particular pattern, appear to form a spiral or twisting pattern, even though the individual circles are actually concentric and not spirals.

The Fraser Spiral Illusion was discovered by the British psychologist James Fraser and was first published in 1908. The illusion occurs due to the interaction between the radial lines connecting the circles and the perceptual system’s interpretation of these lines. The radial lines create an apparent spiral motion, leading to the perception of a spiral pattern emerging from the concentric circles.

The Circle Spiral Illusion highlights how our brain’s interpretation of visual information can lead to misleading perceptions and the creation of illusory patterns. It is an interesting example of how our visual system can be deceived by certain spatial arrangements and cues, resulting in the perception of motion or patterns that do not actually exist.

How does the Circle Spiral Illusion Work?

The Circle Spiral illusion works by exploiting our visual system’s tendency to perceive patterns and motion based on certain visual cues. Here’s an explanation of how it works:

  1. Concentric Circles: The illusion begins with a set of concentric circles, typically with evenly spaced radial lines extending from the center. These circles are truly concentric and have no inherent spiral shape.
  2. Radial Lines: The radial lines are positioned and angled in a way that interacts with our visual system. These lines typically connect the intersections of the circles, creating a series of diagonal lines that appear to spiral inward or outward.
  3. Perceptual Completion: When we observe the concentric circles with the radial lines, our brain tends to complete missing information or fill in gaps based on visual cues and previous experiences. In this case, our brain perceives the missing parts of the spiraling pattern, even though it doesn’t actually exist in the image.
  4. Grouping and Motion Perception: Our visual system naturally groups similar elements and looks for patterns or motion. The arrangement of the radial lines in the Fraser Spiral Illusion gives the impression of a spiraling or twisting motion, as if the circles are forming a spiral pattern.
  5. Contextual Cues: Surrounding context and other visual cues can also influence our perception of the illusion. Elements such as the background or the presence of other patterns may enhance or modify the perceived spiral effect.

The combination of these factors leads to the perception of a spiral pattern emerging from the concentric circles, despite the circles themselves being static and truly concentric. The Circle Spiral Illusion demonstrates how our brain interprets visual information and fills in gaps to construct a coherent perception of the world, sometimes resulting in deceptive patterns or motions that are not actually present in the stimulus.

Some Similar Illusions

There are several illusions that share similarities with the Circle Spiral illusion in terms of creating misleading perceptions of spirals or twisting patterns. Here are a few examples:

  1. The Twisted Cord Illusion: In this illusion, a twisted or coiled rope or cord appears to have a spiral shape when it is unwound. This perception arises due to the interaction between the physical properties of the twisted cord and our visual system’s interpretation of the changing angles and perspective cues.
  2. The Spiral Aftereffect: This illusion occurs after prolonged exposure to spirals rotating in one direction. When you shift your gaze to a stationary image, such as a blank wall, you may perceive illusory spirals rotating in the opposite direction. This phenomenon is a result of neural adaptation and the aftereffects of the motion-sensitive neurons in the visual system.
  3. The Poggendorff Illusion: The Poggendorff illusion involves an oblique line that is interrupted by a rectangular shape. The interruption creates a misalignment in the line segments, making them appear disjointed and causing an illusion of a distorted or misaligned line. The perceived misalignment can create the impression of a spiral-like shape.
  4. The Pinna-Brelstaff Illusion: In this illusion, a pattern of concentric circles or spiral-like shapes, when combined with specific motion, creates the perception of the circles expanding or contracting in size. This effect is due to the interaction between the motion-sensitive neurons in the visual system and the specific arrangement of the patterns.

These illusions, like the Circle Spiral Illusion, manipulate visual cues, perspective, motion, and context to create deceptive perceptions of spirals or twisting patterns. They demonstrate the intricate ways in which our visual system processes and interprets visual information, leading to fascinating illusions and distortions in our perception of reality.

Discovery of the Spiral Illusion

The Circle Spiral illusion is a version of the the Fraser Spiral Illusion, also known as the False Spiral Illusion, was discovered and named after James Fraser, a British psychologist. Fraser first described and published the illusion in his article titled “A New Visual Illusion of Direction,” which appeared in the American Journal of Psychology in 1908. Fraser’s work contributed to the understanding of visual perception and the ways in which our brains interpret visual stimuli to create illusory effects.


References and Resources

In addition to the Circle Spiral Illusion, check out our complete list of illusions and this awesome similar illusions: Platform 9 3-4, Moving Diamond, Moving Ball, Scintillating Stars

Circle Spiral Illusion

Platform 9 3-4 Illusion

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Platform 9/345 Illusion

This awesome Platform 9 3-4 Illusion was created by Matt Pritchard. The Platform 9 3-4 Illusion uses an anamorphic illusion effect to create the famous scene from Harry Potter.

If you are interested in learning more about the Platform 9 3-4 Illusion, scroll down to read more about it.


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What is the Platform 9 3-4 Illusion?

The Platform 9 3-4 Illusion is an anamorphic illusion that recreates the famous platform 9 3/4 scene from Harry Potter.

Platform 9 3/4 is a fictional location in the Harry Potter book series written by J.K. Rowling. In the story, Platform 9 3/4 is a hidden platform at King’s Cross Station in London, which can only be accessed by magical means. It is the departure point for the Hogwarts Express, the train that transports Hogwarts School of Witchcraft and Wizardry students to the school.

In the wizarding world, Platform 9 3/4 is located between platforms 9 and 10. To reach the platform, witches and wizards must pass through a solid barrier between the two platforms. In the books, the entrance to the platform is described as a brick wall, and students must run straight at it with their trolleys in order to magically pass through to Platform 9 3/4.

Platform 9 3/4 is an iconic and significant location in the Harry Potter series, representing the magical world hidden within the ordinary Muggle (non-magical) world. It serves as the gateway for young wizards and witches to begin their journey to Hogwarts School, and it is often depicted as bustling with students, parents, and magical creatures on September 1st, the day of departure for the new school year.

How does the Platform 9 3-4 Illusion Work?

The Platform 9 3-4 Illusion uses an anamorphic illusion effect. Anamorphic illusions are visual distortions that create the perception of a three-dimensional image or object when viewed from a specific vantage point. These illusions manipulate perspective and use the principles of geometry and optics to create the illusion of depth and form. Here’s how illusions like the Platform 9 3-4 Illusion work:

  1. Distorted Perspective: Anamorphic illusions typically start with a distorted or skewed image that appears stretched or elongated when viewed from a normal or frontal perspective. This distorted image does not make sense to our brains when viewed directly.
  2. Correct Viewing Angle: To perceive the intended image or object, the viewer needs to position themselves at a specific vantage point or viewing angle. This angle is carefully calculated to align with the distorted image.
  3. Correct Projection: The distorted image is usually created using mathematical calculations or optical techniques to project the correct shapes and proportions when viewed from the specific angle. This projection ensures that the brain can interpret the distorted image as a recognizable object.
  4. Anamorphic Medium: Anamorphic illusions are often created on a specific medium or surface, such as a cylindrical or conical shape. This medium helps in distorting the image in a way that it can be correctly perceived when viewed from the designated angle.
  5. Optical Illusions: Anamorphic illusions take advantage of our brain’s ability to make sense of visual information based on cues such as perspective, depth perception, and known object shapes. When we view the distorted image from the correct angle, our brain integrates the visual cues and reconstructs the image, creating the illusion of a three-dimensional object or scene.
  6. Artistic Skill: Creating anamorphic illusions requires artistic skill, precision, and understanding of perspective and geometry. Artists carefully calculate the angles, proportions, and distortions to achieve the desired illusion.

Anamorphic illusions like the Platform 9 3-4 Illusion can be seen in various art forms, including street art, paintings, and even digital media. They captivate viewers by challenging their perception and creating seemingly impossible or mind-bending visuals.

Some Similar Illusions

The Platform 9 3-4 Illusion uses an anamorphic illusion effect. There are several other types of illusions similar to anamorphic illusions that play with perception and create fascinating visual effects. Here are a few examples that are similar to the Platform 9 3-4 Illusion:

  1. Optical Illusions: Optical illusions encompass a wide range of visual phenomena that trick the brain into perceiving something different from reality. This can include illusions involving size, color, motion, and depth perception, such as the famous “Müller-Lyer illusion” or the “Rotating Snakes illusion.”
  2. Trompe-l’oeil: Trompe-l’oeil is a technique used in art to create realistic images that give the illusion of three-dimensionality. These artworks can depict objects or scenes that appear to extend beyond the surface or blend seamlessly with the environment.
  3. Forced Perspective: Forced perspective is a technique used in photography and filmmaking to create the illusion of depth or size distortion. By carefully positioning objects or people at specific distances from the camera, the perception of scale and perspective is manipulated.
  4. Moiré Patterns: Moiré patterns are visual interference patterns that occur when two regular patterns overlap or interact, creating a new, often mesmerizing pattern. These patterns can produce the illusion of movement, depth, or shimmering effects.
  5. Stereograms: Stereograms, also known as Magic Eye images, are two-dimensional pictures that contain hidden 3D images. By focusing and adjusting the way the eyes converge, viewers can perceive a hidden three-dimensional scene within the seemingly random patterns.
  6. Ambiguous Figures: Ambiguous figures are images that can be perceived in multiple ways or can switch between different interpretations. Examples include the famous “Necker Cube” or the “Rubin’s Vase,” where the brain can interpret the image in more than one way.
  7. Moiré Effect: The Moiré effect occurs when two regular patterns with slightly different orientations or frequencies are overlaid, resulting in an apparent new pattern. This effect is commonly observed when looking at screens or printed materials with fine grids or lines.

These illusions, like anamorphic illusions like the Platform 9 3-4 Illusion, demonstrate the fascinating ways in which our brains interpret visual information and can be found in various art forms, designs, and everyday visual experiences.

Discovery of the Platform 9 3-4 Illusion

The Platform 9 3-4 Illusion was created by Matt Pritchard.


References and Resources

In addition to the Platform 9 3-4 Illusion, check out our complete list of illusions and this awesome St Peter’s Keyhole Illusion.

Platform 9/345 Illusion

St Peter’s Keyhole Illusion

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St Peter's Keyhole Illusion

This cool St Peter’s Keyhole Illusion is taken from the Piazza Cavalieri di Malta in Rome, Italy.

Looking through the keyhole, you will see a perfectly framed and symmetrical view of the Vatican City, with the dome of St. Peter’s Basilica prominently in the center. The alignment of the keyhole with the avenue creates a remarkable visual effect, as if you are peering into a perfectly composed painting or a meticulously staged scene.

If you are interested in learning more about the St Peter’s Keyhole Illusion, scroll down to read more about it.

St Peter's Keyhole Illusion


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What is the St Peter’s Keyhole Illusion?

The St Peter’s Keyhole Illusion is located in the Piazza Cavalieri di Malta in Rome, Italy. In this particular location, when you approach the keyhole at the main entrance of the priory, you can see a captivating and famous view.

Looking through the keyhole, you will see a perfectly framed and symmetrical view of the Vatican City, with the dome of St. Peter’s Basilica prominently in the center. The alignment of the keyhole with the avenue creates a remarkable visual effect, as if you are peering into a perfectly composed painting or a meticulously staged scene.

The illusion is a result of the careful design and positioning of the keyhole, the avenue, and the distant landmarks. The precise alignment and perspective create a unique visual experience for visitors, providing a glimpse of an iconic view that seems almost surreal.

This optical illusion has made the Piazza Cavalieri di Malta a popular spot for visitors and photographers who seek to capture this captivating view. It demonstrates how careful composition and perspective can create stunning visual effects and leave a lasting impression on those who encounter it.

How does the St Peter’s Keyhole Illusion Work?

The St Peter’s Keyhole Illusion at the keyhole of number 3 in Piazza Cavalieri di Malta relies on a combination of architectural design, perspective, and framing to create a striking visual effect. Here’s how the St Peter’s Keyhole Illusion works:

  1. Framing: The keyhole itself serves as a natural frame for the view. When you look through the keyhole, your field of vision is restricted to the circular opening, effectively creating a frame around the scene you observe.
  2. Forced Perspective: The avenue leading up to the keyhole is intentionally designed to converge and appear narrower as it extends into the distance. This use of forced perspective creates the impression of depth and distance, making the view through the keyhole appear more three-dimensional.
  3. Focal Point Alignment: The keyhole is precisely aligned with the center of the avenue, which creates the illusion of a perfectly centered and symmetrical view. This alignment directs your gaze along the perspective lines of the avenue, drawing your attention to the distant landmark.
  4. Distant Landmark: The key feature of the view seen through the keyhole is the dome of St. Peter’s Basilica in the Vatican City. The dome is strategically positioned in the center of the framed view, which enhances the impact of the illusion. The distant landmark acts as a focal point that draws your eye and adds a sense of grandeur to the scene.

When you look through the keyhole, the convergence of the perspective lines, the framing effect, and the perfectly centered landmark combine to create a visually stunning illusion. The result is a mesmerizing composition that appears as if it were meticulously arranged, even though it is a naturally occurring phenomenon based on the positioning of the keyhole and the surrounding architecture.

This St Peter’s Keyhole Illusion showcases the power of framing, perspective, and precise alignment in creating captivating visual experiences. It demonstrates how careful design choices can manipulate our perception and create illusions that leave a lasting impression.

Discovery of the St Peter’s Keyhole Illusion

The specific origin or creator of the keyhole illusion at Piazza Cavalieri di Malta is not widely documented. The illusion is believed to be a result of the intentional design and positioning of the keyhole and the surrounding architecture rather than the work of a specific individual. The exact details regarding its inception and the intention behind its creation are not readily available.

The Piazza Cavalieri di Malta is a historic location in Rome, Italy, and it is home to the Priory of the Knights of Malta. The keyhole illusion has gained recognition and popularity over time due to its unique visual effect and the captivating view it offers of the Vatican City.

While the exact credit for the creation of the keyhole illusion cannot be attributed to a specific individual, it has become a notable and celebrated attraction for visitors who appreciate the visual spectacle it provides.


References and Resources

In addition to the St Peter’s Keyhole Illusion, check out our complete list of illusions and this fun Elephant or Bird Illusion.

St Peter's Keyhole Illusion

Hidden Eight Illusion

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Hidden Eight Illusion

Can you spot the hidden eight in this Hidden Eight Illusion? In the hidden eight illusion, there is optical illusion that occurs when looking at the eight of diamonds card. In this illusion, the pattern and design on the card, particularly the arrangement of the diamonds, can create the perception of the number “8” hidden within the card. Can you see it? If you need help, click here.

Hidden Eight Illusion
Can you spot the hidden 8?


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What is the Hidden Eight Illusion?

In the hidden eight illusion, there is optical illusion that occurs when looking at the eight of diamonds card . In this illusion, the pattern and design on the card, particularly the arrangement of the diamonds, can create the perception of the number “8” hidden within the card. Can you see it? If

The hidden eight illusion is a result of our brain’s tendency to fill in missing information and make assumptions based on familiar patterns. Even though the actual card does not have the number “8” explicitly drawn on it, our brain tries to make sense of the arrangement of the diamonds and interprets it as an “8.”

This illusion demonstrates how our brains actively interpret visual information and sometimes create perceptions that differ from the actual stimuli. It is a fascinating example of how our perception can be influenced by context, patterns, and our cognitive processes.

How does the Hidden Eight Illusion Work?

The hidden eight illusion works due to a combination of factors, including the arrangement of shapes and patterns on the eight of diamonds card and our brain’s tendency to recognize familiar patterns and fill in missing information.

The eight of diamonds card features a design that includes multiple diamond shapes arranged in a specific pattern. The arrangement of these diamonds creates the illusion of an embedded number “8” when viewed from a particular angle or perspective.

When we look at the card, our brain automatically processes the visual information and attempts to make sense of it. Our brains are wired to recognize and interpret patterns, especially those resembling familiar objects or symbols. In this case, the pattern of diamonds resembles the shape of the number “8,” and our brain fills in the missing segments or lines to complete the perceived shape.

This phenomenon is known as perceptual completion or interpolation. Our brain “fills in the gaps” or completes the missing parts of the pattern based on our past experiences and expectations. In the case of the hidden eight illusion, the arrangement of diamonds is suggestive of the number “8,” and our brain readily interprets it as such.

The hidden eight illusion demonstrates how our perception can be influenced by our brain’s interpretation and processing of visual information. It highlights the complex interplay between our sensory input and cognitive processes, often leading to fascinating optical illusions and perceptual phenomena.

Some Similar Illusions

There are various optical illusions that involve similar principles to the hidden eight illusion. Here are a few examples:

  1. Kanizsa Triangle: The Kanizsa Triangle is an illusion where three illusory white triangles are perceived, even though they are not actually present in the stimulus. Our brain fills in the missing information and completes the triangle shapes based on the angles and contours of the surrounding Pac-Man-like shapes.
  2. Rubin’s Vase: The Rubin’s Vase illusion is a classic example of figure-ground perception. It presents an image that can be interpreted as either a vase or two facing profiles. Depending on how you perceive it, your brain switches between seeing the vase or the faces as the foreground.
  3. Necker Cube: The Necker Cube is a three-dimensional ambiguous figure that can be perceived in two different orientations. Even though the stimulus is a two-dimensional drawing, our brain attempts to interpret it as a three-dimensional cube, resulting in perceptual flipping between the different orientations.
  4. Ponzo Illusion: The Ponzo Illusion is an illusion where two identical lines appear to be of different lengths due to the presence of converging lines or depth cues in the background. Our brain interprets the lines based on their perceived depth, making the line farther away from the converging lines appear longer.
  5. Müller-Lyer Illusion: The Müller-Lyer Illusion involves two lines with arrow-like tails pointing inwards or outwards. Even though the lines are actually the same length, the one with the outward-pointing arrows appears longer. This illusion demonstrates how our brain’s perception of length can be influenced by the surrounding context.

These are just a few examples of the many optical illusions that play with our perception and demonstrate how our brain can be tricked or influenced by various visual cues and patterns. Optical illusions continue to fascinate researchers and provide insights into the complex workings of our visual system.


References and Resources

In addition to the Hidden Eight Illusion, check out our complete list of illusions and this awesome Chromatic Vasarely Illusion and this cool Parallel Lines Illusion and awesome Rotating Circles Illusion and Expanding Contracting Illusion

Hidden Eight Illusion answer

Straight Lines Illusion

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Straight Lines Illusion

In this amazing Straight Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Straight Lines Illusion is works based on the same phenomenon that underpins the famous Cafe Wall Illusion and the Zöllner Illusion.

If you are interested in learning more about the Straight Lines Illusion and the Cafe Wall illusion, scroll down to read more about it.

Straight Lines Illusion
by Akiyoshi Kitaoka


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What is the Straight Lines Illusion?

In the Straight Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Straight Lines Illusion is works based on the same phenomenon that underpins the famous Zöllner Illusion.

The Zöllner illusion is a classic visual illusion that was first described by German astrophysicist Johann Karl Friedrich Zöllner in 1860. The illusion is created by drawing a series of parallel lines at an angle, and then adding diagonal lines that cross over the parallel lines at regular intervals.

When viewed, the diagonal lines create an illusion of a distorted pattern, with the parallel lines appearing to be bent or warped. This distortion appears to be caused by the diagonal lines, which appear to cross over the parallel lines at different angles, even though they are all drawn at the same angle.

The Zöllner illusion is similar to other visual illusions that rely on the misperception of angles and perspective, such as the Poggendorff illusion and the Hering illusion. Like these other illusions, the Zöllner illusion demonstrates how our perception of visual information can be influenced by subtle cues and contextual information in the environment.

How does the Straight Lines Illusion Work?

In the Straight Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Straight Lines Illusion is works based on the same phenomenon that underpins the famous Zöllner Illusion.

The Straight Lines Illusion works like the Zöllner illusion works by manipulating our perception of the angles and orientation of lines in a visual display. When we view the illusion, our brain tries to interpret the angles and orientation of the lines in a way that makes sense based on our previous experiences and knowledge of the world.

In the Zöllner illusion, the parallel lines are placed at an angle, and the diagonal lines are added to cross over them at regular intervals. This creates an array of angles and intersections that can be difficult for the brain to interpret correctly.

When we look at the illusion, our brain tries to perceive the orientation of the diagonal lines in relation to the parallel lines. Depending on how we interpret the angles and intersections, the parallel lines can appear to be either straight or bent or warped.

The exact mechanisms behind the Zöllner illusion and the Straight Lines Illusion are not fully understood, but it is believed to involve a combination of bottom-up processing (the processing of sensory information) and top-down processing (the use of previous knowledge and context to interpret sensory information). The illusion also appears to be influenced by factors such as the distance between the lines, the thickness of the lines, and the orientation of the display.

Some Similar Illusions

There are several other illusions that are similar to the Straight Lines Illusion in that they involve the perception of lines or shapes being distorted by surrounding visual elements. Here are a few examples:

  1. Hering Illusion: This illusion involves the perception of straight lines as curved or bent when they are presented in a context of radiating lines or spokes. It is named after the German physiologist Ewald Hering who first described the illusion in 1861.
  2. Fraser Spiral Illusion: This illusion involves a spiral pattern that appears to be expanding or contracting, even though the spiral itself is actually a series of concentric circles. The illusion is created by the positioning of dark and light segments in the spiral pattern.
  3. Zöllner Illusion: This illusion involves the perception of parallel lines as tilted when they are presented in a context of diagonal lines. The effect is similar to the Cafe Wall illusion, but with diagonal lines instead of staggered rows of squares.
  4. Ponzo Illusion: This illusion involves the perception of two identical lines as different lengths when they are presented in a context of converging lines that create the illusion of depth. The effect is thought to be due to the brain’s interpretation of the converging lines as a cue for distance and size.

These illusions and others like them demonstrate the complex and often surprising ways in which our visual system processes and interprets visual information, highlighting the importance of context and contrast in our perception of the world around us.

Discovery of the Straight Lines Illusion

The Straight Lines Illusion was created by Akiyoshi Kitaoka, a Japanese psychologist and visual perception expert who is known for his research on visual illusions and his creation of many famous optical illusions. He is a professor in the Department of Psychology at Ritsumeikan University in Kyoto, Japan.

The Zöllner illusion was first described by the German astrophysicist Johann Karl Friedrich Zöllner in 1860. Zöllner was interested in the study of perception and visual illusions, and he discovered the illusion while experimenting with different types of geometric patterns. The Zöllner illusion has since become a classic example of visual illusions, and it has been studied extensively by scientists and researchers interested in perception and vision.


References and Resources

In addition to the Straight Lines Illusion, check out our complete list of illusions and this awesome Crescent Moon Bridge Illusion and this cool Yellow Spiral Illusion and awesome Bulge Illusion and Swaying Columns Illusion

Straight Lines Illusion
by Akiyoshi Kitaoka

Bulge Illusion

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Bulge Illusion

In this fun Bulge Illusion by Akiyoshi Kitaoka, the checkerboard pattern appear to bulge even though it is perfectly square. This illusion uses a technique made famous in the checkerboard bulge illusion.

If you are interested in learning more about the Bulge Illusion, scroll down to read more about it.

Bulge Illusion
Akiyoshi Kitaoka


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What is the Bulge Illusion?

The Checkerboard Bulge Illusion is a visual illusion that was first described by Dr. Arthur Shapiro and Professor Zhong-Lin Lu in 1999. This illusion is created by placing a grid of black and white squares over a curved surface, such as a checkerboard on a rounded surface. When the grid is viewed from a certain angle, the white squares appear to bulge out while the black squares appear to be indented.

The Checkerboard Bulge Illusion works because our brains interpret the visual information in a way that makes the curved surface look flat. This means that when we see the white squares on the curved surface, our brain interprets them as being further away from us than the black squares. As a result, the white squares appear to bulge outwards while the black squares appear to be indented.

The Checkerboard Bulge Illusion is a fascinating example of how our brains can be easily tricked by visual information, and how our perception of depth and shape can be influenced by subtle visual cues.

How does the Bulge Illusion Work?

The Checkerboard Bulge Illusion works by manipulating our perception of depth and shape. When we view the illusion, our brain tries to interpret the visual information in a way that makes sense based on our previous experiences and knowledge of the world.

In this illusion, the grid of black and white squares is placed over a curved surface, such as a checkerboard on a rounded surface. The curved surface is designed to create a pattern of shading and perspective cues that suggest a three-dimensional shape to our brain.

When we look at the grid from a certain angle, our brain interprets the white squares as being further away from us than the black squares, even though all the squares are actually on the same flat surface. This causes the white squares to appear to bulge outwards while the black squares appear to be indented.

The illusion works because our brain is trying to interpret the visual information in a way that makes sense based on our previous experiences and knowledge of the world. Our brain is constantly making assumptions about the shape, depth, and perspective of objects in the world around us, and the Checkerboard Bulge Illusion takes advantage of these assumptions to create a convincing illusion of a three-dimensional object on a flat surface.

Some Similar Illusions

There are many similar illusions to the Checkerboard Bulge Illusion that rely on similar visual cues to manipulate our perception of depth and shape. Here are some examples:

  1. Ames Room Illusion: This illusion uses a distorted room to create the illusion of people changing size as they move around the room.
  2. Ponzo Illusion: This illusion uses converging lines to make two identical objects appear to be different sizes.
  3. Müller-Lyer Illusion: This illusion uses arrow-like shapes to make one line appear longer than another, even though they are the same length.
  4. Ebbinghaus Illusion: This illusion uses surrounding circles to make a central circle appear larger or smaller than it actually is.
  5. White’s Illusion: This illusion uses colored squares to make two gray areas appear to be different shades.

All of these illusions work by manipulating visual cues that our brain uses to interpret depth, distance, and perspective. By taking advantage of these cues, the illusions can create surprising and convincing visual effects that can be difficult to explain.

Discovery of the Bulge Illusion

The Checkerboard Bulge Illusion was first described by Dr. Arthur Shapiro and Professor Zhong-Lin Lu in 1999. They published their findings in a scientific article titled “A Simple Method for Detecting Visual Curvature in the Field,” which appeared in the journal Vision Research. In this article, they described the illusion and presented evidence to explain how it works. Since then, the Checkerboard Bulge Illusion has become a popular example of visual illusions and has been studied extensively by scientists and researchers interested in perception and vision.


References and Resources

Check out our complete list of illusions and this awesome Chromatic Vasarely Illusion and this cool Parallel Lines Illusion and awesome Rotating Circles Illusion, Spinning Circles Illusion, and Expanding Contracting Illusion

Bulge Illusion

Concentric Circles Illusion

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Concentric Circles Illusion

This cool Concentric Circles Illusion by Akiyoshi Kitaoka is a version of the famous Frasier Spiral Illusion. In the Concentric Circles Illusion, the shapes are concentric circles that don’t overlap, but they appear to spiral and overlap.

If you are interested in learning more about the Concentric Circles Illusion and the Frasier Spiral illusion, scroll down to read more about it.

Concentric Circles Illusion
by Akiyoshi Kitaoka


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What is the Concentric Circles Illusion?

The Concentric Circles Illusion is a version of the Fraser spiral illusion that was discovered by British psychologist James Fraser in 1908.

The Fraser spiral illusion involves a pattern of concentric circles that appear to spiral outwards from the center, even though the circles are actually arranged in perfectly straight lines. The illusion is created by the positioning of alternating black and white segments along the circumference of each circle, which creates a visual “flutter” effect that gives the impression of a spiral.

The illusion is an example of how our brains try to make sense of complex visual patterns by filling in missing information and making assumptions based on context and prior experience. The Fraser spiral illusion is a popular example in the study of visual perception, and has been used to explore the underlying neural mechanisms that contribute to our perception of visual patterns and motion.

How does the Concentric Circles Illusion Work?

The Concentric Circles Illusion is a version of the Fraser spiral illusion.

The Fraser spiral illusion works by exploiting the way our visual system processes information about edges and contrast. The illusion is created by a pattern of alternating black and white segments that are arranged along the circumference of a series of concentric circles. These segments are positioned so that they alternate in such a way that the contrast between adjacent segments is maximized, creating a visual “flutter” effect at the edges where they meet.

When we look at the pattern, our brain interprets the alternating black and white segments as a series of curved lines that spiral outwards from the center of the pattern. This is because our brain tries to make sense of the pattern by filling in missing information and assuming that the lines are curved, even though they are actually arranged in straight lines.

The illusion is also influenced by the contrast between adjacent segments. The high contrast between the black and white segments enhances the perceived curvature of the lines, creating the illusion of a spiral where none exists.

The Concentric Circles Illusion and the Fraser spiral illusion demonstrates how our brain interprets visual patterns based on context and prior experience, and highlights the importance of contrast and edge detection in our perception of visual motion and shape.

Some Similar Illusions

There are several other illusions that are similar to the Concentric Circles Illusion in that they involve the perception of curvature or motion where none actually exists. Here are a few examples:

  1. Poggendorff Illusion: This illusion involves the perception of a discontinuity or misalignment in a diagonal line that is obscured by a vertical or horizontal line that crosses over it. The illusion can create the impression of a bend or offset in the diagonal line where none actually exists.
  2. Lilac Chaser Illusion: This illusion involves the perception of a rotating “hole” in a ring of colored disks that creates the illusion of a moving spot of light. The effect is thought to be due to the brain’s perception of motion contrast and afterimages.
  3. Orbison Illusion: This illusion involves the perception of a rotating spiral pattern that appears to change direction after a period of time. The illusion is created by the brain’s tendency to perceive motion based on the contrast between adjacent areas of color and brightness.
  4. Müller-Lyer Illusion: This illusion involves the perception of two lines of equal length that appear to be different lengths due to the presence of arrowheads at the ends of the lines. The illusion is thought to be due to the brain’s use of context and perspective cues to interpret visual information.

The Concentric Circles Illusion and others like it demonstrate the complex and often surprising ways in which our visual system processes and interprets visual information, highlighting the importance of context and contrast in our perception of the world around us.

Discovery of the Concentric Circles Illusion

The Concentric Circles Illusion was created by Akiyoshi Kitaoka, a Japanese psychologist and visual perception expert who is known for his research on visual illusions and his creation of many famous optical illusions. He is a professor in the Department of Psychology at Ritsumeikan University in Kyoto, Japan.

The Fraser spiral illusion was discovered by British psychologist James Fraser in 1908. Fraser was interested in the way that our visual system processes information about motion and shape, and he used the spiral illusion as an example of how the brain can be tricked into perceiving motion or curvature where none actually exists.

Fraser’s work on the spiral illusion was part of a broader effort by psychologists and neuroscientists to understand how the brain processes and interprets visual information. Today, the illusion remains a popular example in the study of visual perception, and has been used to explore a range of topics, from the neural mechanisms of motion perception to the role of context and prior experience in shaping our perceptions of the world around us.


References and Resources

In addition to the Concentric Circles Illusion, check out our complete list of illusions and this awesome Crescent Moon Bridge Illusion and this cool Parallel Lines Illusion and awesome Rotating Circles Illusion

Concentric Circles Illusion
by Akiyoshi Kitaoka

Parallel Lines Illusion

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Parallel Lines Illusion

In this amazing Parallel Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Parallel Lines Illusion works based on the same phenomenon that underpins the famous Cafe Wall Illusion.

If you are interested in learning more about the Parallel Lines Illusion and the Cafe Wall illusion, scroll down to read more about it.

Parallel Lines Illusion
by Akiyoshi Kitaoka


Table of Contents

What is the Parallel Lines Illusion?

In the Parallel Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Parallel Lines Illusion is works based on the same phenomenon that underpins the famous Cafe Wall Illusion.

The Cafe Wall illusion is a type of optical illusion that involves a pattern of black and white squares arranged in a staggered “brick-like” pattern, which gives the impression that the horizontal rows of squares are sloping or tilted. The illusion is named after its resemblance to the tiled walls of cafes, and was first described by British psychologist Richard Gregory in 1973.

Despite the appearance of the tilted rows, the squares themselves are actually arranged in perfectly straight horizontal and vertical lines. The illusion occurs because the visual system tries to interpret the pattern in terms of alternating rows of black and white “bricks,” causing the perceived slanting effect.

The Cafe Wall illusion is an example of how our brains try to interpret visual information and make sense of complex patterns, even when the information is ambiguous or misleading. The illusion has become a popular example in psychology and neuroscience, and has been studied as a way to understand how the brain processes visual information

How does the Parallel Lines Illusion Work?

In the Parallel Lines Illusion by Akiyoshi Kitaoka, the horizontal lines appear to tilt but in fact they are perfectly parallel. The Parallel Lines Illusion is works based on the same phenomenon that underpins the famous Cafe Wall Illusion.

The Parallel Lines Illusion works like the Cafe Wall Illusion which exploits the way our visual system processes information about edges and contrast. The illusion is created by a pattern of black and white squares arranged in a staggered “brick-like” pattern. Each row of squares is shifted slightly to the left or right relative to the row above or below it, creating a series of “V” shapes where the rows meet.

When we look at the pattern, the staggered rows of black and white squares create a perceived gradient in brightness along each row. This gradient creates the illusion of a slope or tilt in the horizontal rows of squares, even though they are arranged in perfectly straight lines.

The illusion is also influenced by the contrast between adjacent squares. The light and dark squares create a visual “flutter” effect at the edges where they meet, which can reinforce the perceived tilt of the rows.

The Parallel Lines Illusion and the Cafe Wall Illusion demonstrate the importance of context and contrast in our perception of visual patterns. By manipulating these factors, the illusion can create a striking and seemingly paradoxical effect, highlighting the complex and often subtle ways in which our visual system interprets the world around us.

Some Similar Illusions

There are several other illusions that are similar to the Parallel Lines illusion in that they involve the perception of lines or shapes being distorted by surrounding visual elements. Here are a few examples:

  1. Hering Illusion: This illusion involves the perception of straight lines as curved or bent when they are presented in a context of radiating lines or spokes. It is named after the German physiologist Ewald Hering who first described the illusion in 1861.
  2. Fraser Spiral Illusion: This illusion involves a spiral pattern that appears to be expanding or contracting, even though the spiral itself is actually a series of concentric circles. The illusion is created by the positioning of dark and light segments in the spiral pattern.
  3. Zöllner Illusion: This illusion involves the perception of parallel lines as tilted when they are presented in a context of diagonal lines. The effect is similar to the Cafe Wall illusion, but with diagonal lines instead of staggered rows of squares.
  4. Ponzo Illusion: This illusion involves the perception of two identical lines as different lengths when they are presented in a context of converging lines that create the illusion of depth. The effect is thought to be due to the brain’s interpretation of the converging lines as a cue for distance and size.

These illusions and others like them demonstrate the complex and often surprising ways in which our visual system processes and interprets visual information, highlighting the importance of context and contrast in our perception of the world around us.

Discovery of the Parallel Lines Illusion

The Parallel Lines Illusion was created by Akiyoshi Kitaoka, a Japanese psychologist and visual perception expert who is known for his research on visual illusions and his creation of many famous optical illusions. He is a professor in the Department of Psychology at Ritsumeikan University in Kyoto, Japan.

The Cafe Wall illusion was first described by British psychologist Richard Gregory in 1973. Gregory noticed the illusion on a tiled wall outside a cafe in Bristol, England, and became fascinated by the way the pattern of tiles appeared to be sloping even though it was made up of perfectly straight lines.

Gregory went on to study the illusion in more detail, conducting experiments to investigate how the brain processes visual information to create the illusion. His work on the Cafe Wall illusion helped to shed light on the complex and dynamic nature of visual perception, and has become a classic example in the field of cognitive psychology and neuroscience.


References and Resources

In addition to the Parallel Lines Illusion, check out our complete list of illusions and this similar Straight Lines Illusion and this cool Yellow Spiral Illusion and awesome Rotating Circles Illusion and Swaying Columns Illusion

Parallel Lines Illusion
by Akiyoshi Kitaoka

Rotating Circles Illusion

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Rotating Circles Illusion

In this Rotating Circles Illusion by Akiyoshi Kitaoka, there are two cool effects. First, the interior spheres appear to move despite the image being completely static. In this way, the Rotating Circles Illusion is an example of illusory motion. Second, the light green shapes are perfect circles, but can appear hexagonal due to the design and location of the interior spheres. In this way, this is also a geometric illusion.

If you are interested in learning more about the Rotating Circles Illusion, illusory motion, and geometric illusions, scroll down to read more about it.

Rotating Circles Illusion
by Akiyoshi Kitaoka


Table of Contents

What is the Rotating Circles Illusion?

The Rotating Circles illusion is an example of illusory motion. Illusory motion is a type of visual illusion that creates the perception of movement where there is none. This can happen in various ways, such as when stationary images are presented in rapid succession, or when static images are presented in a way that creates the impression of movement.

One example of illusory motion is the phi phenomenon, which is the perception of motion created by presenting two or more stationary images in rapid succession. This is the principle behind many types of animation, such as flipbooks and animated movies.

Another example of illusory motion is the motion aftereffect, also known as the waterfall illusion. This occurs when a person views a moving stimulus for an extended period of time, and then looks at a stationary object, which appears to be moving in the opposite direction.

Illusory motion can also occur through the use of optical illusions, such as the rotating snakes illusion, which creates the impression of snakes that are rotating when in fact the image is static.

Illusory motion is often used in art and entertainment, such as in animation, film, and video games, to create a sense of movement and to captivate the viewer.

The Rotating Circles illusion is also an example of a geometric illusions.

Geometric illusions are a type of visual illusion that involve distorted or misperceived shapes, patterns, or spatial relationships. These illusions occur because of the way our brain processes and interprets visual information. Our visual system relies on a combination of sensory input and cognitive processing to make sense of the world around us, but sometimes this processing can lead to errors or misperceptions.

How does the Rotating Circles Illusion Work?

The Rotating Circles Illusion is an example of illusory motion. Illusory motion is caused by the way that our brain processes visual information. When we view images, our brain constructs a mental representation of what we are seeing. This representation is based on the input from our eyes, but it is also influenced by our past experiences and expectations.

Illusory motion can occur when our brain processes visual information in a way that creates the perception of movement where there is none. This can happen when the brain is presented with visual stimuli that are ambiguous or incomplete. In these cases, the brain fills in the missing information, sometimes creating a perception of movement.

Illusory motion is a result of the complex interplay between visual input, past experiences, and the brain’s interpretation of that information.

Some Similar Illusions

There are many other types of illusions that are similar to illusory motion in that they involve a discrepancy between what we perceive and what is actually present in the visual input. In addition to the Rotating Circles, here are a few examples:

  1. Optical illusions: These are images that create a perception of something that isn’t actually there or that distort the way we perceive an object. Examples include the famous “Müller-Lyer illusion,” which makes two lines of equal length appear to be different lengths due to the addition of arrowheads at the ends of the lines.
  2. Tactile illusions: These illusions involve a discrepancy between what we feel and what is actually happening to our body. One example is the “rubber hand illusion,” in which a person’s brain can be tricked into perceiving a rubber hand as their own due to the synchronous stimulation of both the rubber hand and their real hand.
  3. Auditory illusions: These illusions involve a discrepancy between what we hear and what is actually present in the auditory input. Examples include the “McGurk effect,” in which the perception of speech sounds can be influenced by the visual input of a speaker’s mouth movements.
  4. Cognitive illusions: These illusions involve a discrepancy between what we think we know and what is actually true. Examples include the “conjunction fallacy,” in which people tend to believe that a specific combination of characteristics is more likely than a more general category.
  5. Perceptual constancy illusions: These illusions involve a discrepancy between the perceived size, shape, or color of an object and its actual size, shape, or color. One example is the “size-weight illusion,” in which people tend to perceive smaller objects as heavier than larger objects of equal weight.

There are many different types of geometric illusions, but some common examples include:

  1. Size illusions: These illusions make objects appear larger or smaller than they actually are. One example is the “Ebbinghaus illusion,” in which a circle appears smaller when surrounded by larger circles, and larger when surrounded by smaller circles.
  2. Shape illusions: These illusions involve misperceptions of the shapes of objects. One example is the “Müller-Lyer illusion,” in which two lines of the same length appear to be different lengths because of the addition of arrowheads at the ends of the lines.
  3. Perspective illusions: These illusions create the impression of depth or distance in a two-dimensional image. One example is the “Ponzo illusion,” in which two parallel lines appear to be different lengths because of the addition of converging diagonal lines.
  4. Contrast illusions: These illusions involve the misperception of brightness or color. One example is the “Simultaneous Contrast illusion,” in which the same color appears different depending on the colors that surround it.

Illusions of various types can be fascinating and informative, as they provide insight into the complex ways in which our brains interpret and process sensory information.

Discovery of the Illusory Motion – Rotating Circles Illusion

The Rotating Circles Illusion was created by Akiyoshi Kitaoka, a Japanese psychologist and visual perception expert who is known for his research on visual illusions and his creation of many famous optical illusions. He is a professor in the Department of Psychology at Ritsumeikan University in Kyoto, Japan.

Kitaoka’s work has focused on the study of perception, specifically on how the brain processes visual information and creates the experience of seeing. He has developed a number of visual illusions that demonstrate how the brain can be tricked into perceiving things that are not actually there or that are different from reality.

Some of Kitaoka’s most famous illusions include the Rotating Snakes illusion, the Checker Shadow illusion, and his work on the Fraser Spiral illusion. His work has been featured in scientific journals and popular media around the world, and he is considered one of the leading researchers in the field of visual perception.

The study of illusory motion and visual perception is a collaborative and ongoing field of research, with many researchers contributing to our understanding of these complex phenomena.

Geometric illusions like the hexagonal appearance in the rotating circles illusion are also a fascinating and complex area of study within the fields of visual perception and cognitive psychology. They provide insight into the ways in which our brains interpret and process visual information, and can also be used in a variety of practical applications, such as graphic design and architecture.


References and Resources

In addition to the Rotating Circles Illusion, check out our complete list of illusions and this awesome Moving Dots Illusion and this cool Mona Lisa Bar Illusion and awesome House Painting Illusion

Rotating Circles Illusion
by Akiyoshi Kitaoka

House Painting Illusion

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House Painting Illusion

In this House Painting Illusion the painting on the building has been done upside down so that it shows up correctly in the reflection!

This House Painting Illusion is an example of mirrored art (sometimes called reflective art) which is created in such a way that the image or design is intentionally mirrored, either horizontally or vertically, so that when it is reflected in a mirror or reflective surface, it creates a new and unique image.

If you are interested in learning more about this House Painting Illusion and mirrored art, scroll down to read more about it.

House Painting Illusion


Table of Contents

What is the House Painting Illusion ?

In the House Painting Illusion the painting on the building has been done upside down so that it shows up correctly in the reflection!

This House Painting Illusion is an example of mirrored art which is created in such a way that the image or design is intentionally mirrored, either horizontally or vertically, so that when it is reflected in a mirror or reflective surface, it creates a new and unique image.

How does the House Painting Illusion Work?

The House Painting Illusion is an example of Mirrored Art.

Mirrored art can be created using a variety of mediums, including painting, drawing, sculpture, and photography. It can also be created using digital media, such as graphic design and video.

Mirrored art can be used for various purposes, such as creating optical illusions or exploring the concept of reflection and symmetry. It can also be used to create artworks that have different meanings or interpretations when viewed in the mirror compared to when viewed directly.

Mirrored art works by intentionally creating a design or image that is symmetrical in nature, either horizontally or vertically. When the artwork is reflected in a mirror, the mirror image will also be symmetrical and will create a new and unique image.

For example, let’s say an artist creates a painting of a butterfly with symmetrical wings. If the artist intends for the painting to be mirrored, they would create the butterfly with the exact same symmetry on both sides, so that when it is reflected in a mirror, the mirrored image will also be symmetrical and create a new image of a butterfly with wings in a different position.

Another example is using typography to create mirrored art. An artist could create a word or phrase with a symmetrical typeface, and then place the text in such a way that it forms a symmetrical shape. When the artwork is reflected in a mirror, the mirrored image will also form a symmetrical shape, but with the text reading in the opposite direction.

In both cases, the mirrored art creates a new and unique image that is different from the original, but still maintains the same underlying symmetry and design elements.

Some Similar Illusions

There are many forms of art and illusion that share similarities with the House Painting Illusion and mirrored art. Here are a few examples:

  1. Reflection art: Reflection art involves the use of reflective surfaces, such as mirrors, water, or metal, to create a unique visual effect. Like mirrored art, reflection art plays with symmetry and can create new and interesting images.
  2. Op art: Op art, short for “optical art,” is a style of art that creates optical illusions through the use of patterns, lines, and colors. Op art often plays with perception and can make the viewer question what they are seeing, much like mirrored art.
  3. Trompe l’oeil: Trompe l’oeil, which translates to “trick the eye,” is a type of art that creates a realistic illusion of three-dimensional space on a two-dimensional surface. Like mirrored art, trompe l’oeil can make the viewer question what they are seeing and create a sense of visual surprise.
  4. Anamorphic art: Anamorphic art is a form of art that uses perspective and distortion to create a hidden image that is only revealed when viewed from a certain angle. Like mirrored art, anamorphic art can create a sense of surprise and wonder when the hidden image is revealed.
  5. Kinetic art: Kinetic art involves the use of movement to create a dynamic visual effect. Like mirrored art, kinetic art can create a sense of surprise and wonder through its use of movement and unexpected visual effects.

Mirrored Art and the House Painting Illusion

Mirrored art like the House Painting Illusion has been explored and used by many artists throughout history. Here are a few examples of artists who have either pioneered or are popular for their work in mirrored art:

  1. Yayoi Kusama: Yayoi Kusama is a Japanese artist who is well-known for her mirrored installations. Kusama’s work often involves the use of mirrored surfaces to create immersive environments that play with perception and the viewer’s sense of self.
  2. Anish Kapoor: Anish Kapoor is a British-Indian sculptor who is famous for his mirrored sculptures. Kapoor’s sculptures often use reflective surfaces to distort and manipulate the viewer’s perception of space and form.
  3. Olafur Eliasson: Olafur Eliasson is a Danish-Icelandic artist who is known for his immersive installations that often incorporate mirrored surfaces. Eliasson’s work explores themes of perception, light, and space, and often encourages viewer interaction and participation.
  4. Robert Smithson: Robert Smithson was an American artist who is known for his pioneering work in earth art and land art. Smithson’s “Mirror Displacements” series, created in the late 1960s and early 1970s, involved placing large, mirrored surfaces in remote landscapes, creating a sense of displacement and disorientation for the viewer.
  5. Monir Shahroudy Farmanfarmaian: Monir Shahroudy Farmanfarmaian was an Iranian artist who was known for her intricate mirrored mosaics. Farmanfarmaian’s work drew on Islamic art and architecture and often used mirrored surfaces to create complex geometric patterns and designs.


References and Resources

In addition to the House Painting Illusion, check out our complete list of illusions and this awesome Crescent Moon Bridge Illusion and this cool Mona Lisa Bar Illusion and awesome Moving Heart Illusion.

House Painting Illusion