First prize: Cogs in a machine

Authors: Jacky Z. J. Yueh, Joan Danielle K. Ongchoco

Country: Canada

Description: Making sense of the causal connections between objects is not just a task of reasoning. We can also sometimes perceive these connections, as when two discs collide with each other. Beyond collisions, might perception extract more complex causal dynamics? Here we introduce a “rotating gears” illusion: if you fixate on one of two gears rotating side-by-side at the same speed, the adjacent gear will appear to rotate faster when the gears are causally connected versus not. Thus, our perception of dynamic properties, such as speed, may be altered by the underlying causal mechanics of the system.

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Second prize: 9 Purple Dots


Author: Hinnerk Schulz-Hildebrandt

Country: USA

Description: This illusion reveals a surprising property of color perception: when purple elements are shown on a bluish background, only the element you directly look at appears purple—while all others shift toward blue. As you move your gaze, the purple “spotlight” follows your eyes, and with increasing viewing distance, more and more elements gradually turn purple again. The effect is robust, and easily reproducible on a digital screen.

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Third Prize: The Hole Truth

Author: Dr Matt Pritchard

Country: UK

Description: A sign with cut out letter holes makes a different word when reflected in the mirror. One side reads true, the other false. The sign becomes a 3D ambigram. It incorporates a variation of the liar paradox created by Philip Jourdain where the two statements are logical incompatible. The video also has variations using different word combinations and the famous duck/rabbit illusion. The final shadow effect is left as a mystery for the viewer.

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Anti-Gravity Snow Slopes

Authors: Kokichi Sugihara, Ryoichi Takahashi, Noboru Okamura, Ikeda Art Museum, Hakkai-Sanroku Green Club

Country: Japan

Description: This object was constructed by snow on March 2025 at Hakkai-Sanroku Sky Resort in Minami-Uonuma City, Niigata Prefecture, Japan. The object shape was designed by Kokich Sugihara according to his 3D illusion theory to fit the land shape. The event was organized by Ryoichi Takahashi, director of Ikeda Art Museum, and the slope construction was directed by Noboru Okamura, the president of Hakkai-Sanroku Green Club and performed by the members of Ikeda Art Museum and Hakkai-Sanroku Green Club.

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Illusion Stereograms

Author: John Salmon

Country: USA

Description: This illusion blends traditional stereograms with popular optical illusions to create an immersive 3D experience without special glasses. By slightly crossing your eyes or looking through the screen, your eyes view two side-by-side, repeating geometric patterns at different angles. Your brain automatically merges these separate 2D images, to construct an apparent three-dimensional shape. As the views and patterns interact, the hidden object (in this case, an optical illusion) appears to pop directly out of the screen or float in space. It turns a flat display into an intriguing display of depth perception, showcasing how our brain interprets visual depth and motion.

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Linton Color Constancy Illusion

Author: Paul Linton

Country: USA

Description: One of the central questions in cognitive psychology is how we distinguish perception (what we visually experience) from cognition (what we think or judge about what we see). Color constancy illusions are generally thought to fall on the perception side of this divide: changing the surrounding context of a disk appears to change the color of the disk itself. But is this really a change in visual experience, or merely a change in how we interpret and judge the color? The Linton Color Constancy Illusion challenges the traditional view, suggesting that this effect reflects our cognition rather than our perception.

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The Bending Strings Illusion

Author: Nuno Alexandre De Sá Teixeira

Country: Portugal

Description: In the Bending Strings Illusion, perfectly straight lines – here embedded in a guitar drawing to resemble its strings – appear squiggly or wavy when placed between straight dotted lines. The illusory squiggles appear stronger in peripheral vision. Several variations are presented, each affecting the illusion to different degrees. The behaviour of the illusion hints at the likely involvement of early visual mechanisms. I found this illusion while preparing a diagram for a class, with alternating straight and dotted lines – what at first seemed to be yet another software glitch turned out, after careful inspection, to be just an optical effect.

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The Bubble Illusion

Authors: Masataka Suzuki, Masayo Noda, Kazufumi Takahashi

Country: Japan

Description: Our video contains three still images. The first image shows 16 transparent discs randomly arranged on a black background so that they partially overlap each other. If you look at the whole image with keeping fixation on a central cross, you will immediately notice that one disc appears to be nearer and brighter than the others. This scheme will be succeeded in one of the other discs even in the absence of eye movements, as if a new bubble appears one after another on the surface of water. The second image shows the contours of all the circles in the first image, drawn with only the solid lines. Surprisingly, the dynamic changes in the depth order among circles, which are similar to that experienced in the transparent situation, can be confirmed. However, when the depth order of overlapping circles is uniquely determined, as shown in the third image, perceptual alternation never occurs. When faced with ambiguous images, like those in the first two images, our brain appears to work diligently to find a unique solution.

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Triangles are Amazing: What is in the Box?


Authors: Andrew W. Piotrowski, Gideon Paul Caplovitz

Country: USA

Description: Triangles may be simple shapes, but in certain configurations they are truly amazing! Here, a large red triangle is partially covered by six smaller black triangles all lying flat in the two-dimensional plane. With little effort, one can almost feel the brain re-organize this visual input into a three-dimensional experience of a red ‘propeller’-like shape in front of a black box. The box has gaps along its edges and if you look closely, you’ll see something in the box! The straight edges of the triangles give rise to curvature. What is it? What is in the box? It’s a circle!

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Stroboscopic Effect in a Phenakistiscope

Author: Astuto Santosa

Country: Indonesia

Description: It is a common experience when watching movies that a car wheel can appear stationary, or spin forward or backward. This is called the stroboscopic effect, which happens when the motion of a rotating object is sampled at a particular frame rate. The same effect can be seen in a phenakistiscope, which in this example has 12 pictures. The character appears almost stationary when the disk rotates at 1.25 rps. However, when the rotation speed is changed, the result is different! This shows that our perception of rotating objects depends on temporal sampling. I observed this effect while making a video for my phenakistiscope design.

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