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Human Perception of the Anomalous Mirror Symmetry Illusion

17 reviews


Areas of Science
Time Required
Average (6-10 days)
Ben Finio, PhD, Science Buddies
Illusions based on the work of Dr. Kokichi Sugihara
*Note: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

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The Science Buddies project Design Your Own 3D Printed Optical Illusion shows you how to make your own 3D printed "anomalous mirror symmetry" illusions (Figure 1). The illusions are based on the work of Dr. Kokichi Sugihara. You can read his original paper about the illusions in the Bibliography.

Two versions of the 3D printed impossible arrow that use different triangulation methods for their top surface. One connects triangles across the shape to opposite edges, and one connects triangles to a central point. Both arrows appear to point to the right while their reflection ns in a mirror appear to point to the left.
Figure 1. Two versions of the "impossible arrow" shape that appears to point to the right while its reflection in the mirror appears to point to the left. Which version of the shape do you find to be a more convincing illusion?

A key part of the illusion is your brain's assumption that the top of the shape is flat. However, as you will see if you watch this video, that is not true. The top and bottom surfaces of the shape have a three-dimensional profile.

For a science project, could you explore the factors that affect human perception of this illusion? For example:


icon scientific method

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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Finio, Ben. "Human Perception of the Anomalous Mirror Symmetry Illusion." Science Buddies, 31 May 2022, https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBeh_p064/human-behavior/anomalous-mirror-symmetry-illusion?from=Blog. Accessed 12 Apr. 2024.

APA Style

Finio, B. (2022, May 31). Human Perception of the Anomalous Mirror Symmetry Illusion. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBeh_p064/human-behavior/anomalous-mirror-symmetry-illusion?from=Blog

Last edit date: 2022-05-31
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