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Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →The Phantom Queen by Matt Pritchard won the 2021 Best Illusion of the Year Contest. The Changing Room Illusion took second prize, and the Double Ring Illusion placed third. Together they show how perspective, attention, motion and assumptions can make perception diverge from the physical scene.
The contest’s official archive is the authoritative ranking for 2021. The examples below combine those finalists with representative illusions highlighted in a 2021 roundup by Creative Bloq.
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| 1 |
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Optical Illusions: The Science of Visual Perception (Illusion Works) | $19.87 | Buy on Amazon |
What counts as an optical illusion?
The contest defines an illusion as “perceptual experiences that do not match the physical reality.” Vision is not a direct recording of the world: the brain constructs a useful interpretation from incomplete sensory signals, context and prior expectations. Studying those errors helps researchers understand sensory perception and some ophthalmic and neurological diseases.
The Best Illusion of the Year Contest has been running since 2005, pairing public demonstrations with research into how perception works.
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The three 2021 contest winners
| Place | Illusion | Creator(s) | Main cue | What appears to happen |
|---|---|---|---|---|
| 1st | The Phantom Queen | Matt Pritchard (UK) | Perspective, mirror and camouflage | A white chess queen appears only in the mirror, although the physical setup hides it from the direct viewing angle. |
| 2nd | The Changing Room Illusion | Michael A. Cohen (Amherst College/MIT, USA) | Attention and gradual change | Dozens of objects change while viewers fail to notice the alterations. |
| 3rd | The Double Ring Illusion | Dawei Bai and Brent Strickland (France/Morocco affiliations) | Motion and occlusion | Two rings seem to switch between full 360-degree rotation and a stable 180-degree oscillation when they overlap. |
1. The Phantom Queen
Pritchard’s winning video places a chessboard and mirror so that a phantom white queen is visible in reflection but not from the ordinary viewing angle. An invisibility cloak conceals the queen in the direct view and is disguised in the mirror view as well. The demonstration also includes anamorphic camouflage and an “invisible cube.”
The effect is a geometry problem rather than a disappearing object: the arrangement controls which surfaces and shapes line up from each viewpoint. Move away from the intended position and the concealment breaks down.
2. The Changing Room Illusion
Cohen’s second-prize demonstration presents gradual, or “graduate,” change blindness. Items in a room can be replaced or altered one after another, yet observers often do not report the changes. Because no single abrupt switch demands attention, the visual system can preserve a broad sense of the scene while failing to compare every object across time.
Rank #2
Cohen argues that the example may also suggest the opposite of the usual lesson: people could perceive and remember more of a scene than they consciously realize, even when they cannot identify each change.
3. The Double Ring Illusion
Two separate bistable rings appear to rotate unpredictably through 360 degrees. When they overlap, the same motion is interpreted as a stable 180-degree back-and-forth oscillation, as if the rings cannot pass through one another. Adding holes that allow one ring to traverse the other restores the 360-degree percept.
The changing interpretation shows how the visual system uses occlusion and object-continuity assumptions to decide which motion is physically plausible.
Other official 2021 finalists
Crocs & Socks
Under green lighting, viewers’ beliefs about whether the socks are white influence whether the crocs look pink or grey. The finalist isolates the interaction between illumination assumptions and colour perception.
Emergent City Flyby with Colossus
Motion parallax creates a vivid city and giant while the viewer moves. Stop the movement and the structured scene disappears, demonstrating how the brain extracts three-dimensional form from changing image motion.
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Oh La La Box
Two pieces built with inverted perspective fuse into a normal-looking box from one precise viewpoint. From other positions, the distorted construction becomes apparent.
Rank #4
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Slime Hand
A mirror, slime and touch produce the feeling that a hidden hand is stretched and transformed. The trick targets body ownership: visual and tactile signals can make an artificial or displaced body part feel like one’s own.
Rising Object Illusion
A horizontal object appears to rise in a vertical mirror. The archive attributes the geometry to a 1.41, or square-root-of-two, expansion viewed at 45 degrees.
Cubic Confusion
Coloured wood veneers laid on a flat surface compel viewers to interpret the pattern as a three-dimensional cube, showing how shading and colour relationships trigger depth assumptions.
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The Phantom Wiggle
Flicker and frame smear make a light appear to dance or wiggle when it is fixated. The motion is generated by the display sequence and the visual system’s response to temporal changes, not by the light physically moving in the same way.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Standout illusions from Creative Bloq’s 2021 roundup
Amelia Bamsey’s Creative Bloq roundup, published 3 January 2022, widened the year’s selection beyond the contest archive. Its examples included:
- A spinning-circles effect that turns repeated circular patterns into apparent motion.
- A black-and-white photograph that appears coloured through a colour-assimilation grid; one calculation cited in the article found only 36% of the image was coloured.
- Identical orange squares that look different when placed on a gradient.
- The “true cyan” afterimage exercise, in which staring at one colour produces a complementary afterimage.
- Strijdom van der Merwe’s Staircase to Heaven.
- Soulwax’s hidden album title, concealed through visual design.
- A perspective trick that changes the apparent size of a car.
- A reverse-phi effect featuring jumping ninjas, in which carefully timed contrast reversals create perceived motion.
How the 2021 illusions differ
| Perceptual cue | Representative examples | Viewing condition | What supplies the false percept | Participation |
|---|---|---|---|---|
| Perspective and geometry | The Phantom Queen; Oh La La Box; Rising Object; Cubic Confusion | Specific viewpoint, mirror or flat arrangement | Shape alignment, scale and depth assumptions | Mostly watch-only demonstrations; some can be rebuilt with careful geometry. |
| Attention and change | The Changing Room Illusion | Gradual substitutions over time | Failure to compare unattended moments | Watch-only unless a second person controls the changes. |
| Motion processing | The Double Ring; Emergent City Flyby; Phantom Wiggle; reverse phi | Overlap, camera movement, flicker or frame sequences | Continuity, parallax and temporal integration | Usually video-based. |
| Colour and lighting | Crocs & Socks; colour-assimilation grid; orange squares; true cyan | Coloured surround, unusual illumination or adaptation | Context, assumed lighting and afterimages | Several are safe to try with an ordinary screen and short viewing periods. |
| Body ownership | Slime Hand | Mirror plus coordinated touch | Conflicting visual and tactile body signals | Interactive demonstration; stop if uncomfortable. |
Safe ways to experience the effects
- Watch each official finalist from the intended viewpoint first, then replay while looking for the construction or viewpoint change.
- For colour effects, use a normal screen, keep room lighting steady and take breaks; afterimages fade when you look away.
- Do not stare at intense flicker if you are sensitive to flashing light or have a photosensitive condition.
- For change-blindness demonstrations, have another person introduce slow substitutions and tell you afterward what changed; avoid moving hazards or distracting someone near traffic, stairs or machinery.
- For mirror or body-ownership experiments, use a stable setup and stop immediately if you feel dizzy, distressed or disoriented.
Why these illusions matter
The 2021 selection is not a list of tricks that all fool vision in the same way. The Phantom Queen and Oh La La Box exploit viewpoint-dependent geometry; Crocs & Socks tests assumptions about illumination; the Changing Room Illusion exposes limits of attention over time; and the Double Ring Illusion shows that the brain favours a physically coherent story when objects overlap. Comparing the cue, viewing condition and reveal makes each illusion easier to understand than simply labeling it “a visual trick.”
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