======Ebbinghaus Illusion======


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**Alternative titles:** Relative Size Illusion
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====Summary====                   
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====Procedure====  
  - Draw or project two identical central circles.
  - Surround one central circle with several larger circles placed close around it.
  - Surround the other central circle with several smaller circles placed close around it.
  - Ask observers which central circle looks bigger.
  - Reveal that both central circles are exactly the same size.



====Links==== 
The Ebbinghaus Illusion | Optical Illusions - Contact Lens King: 
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Explaining Optical Illusions: Part 4 - The Ebbinghaus Illusion and the Flash lag effect - 
Learning Curve: 
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📄 Ebbinghaus illusion - Wikipedia: [[https://en.wikipedia.org/wiki/Ebbinghaus_illusion]]\\


====Variations====
  * Change the distance between the central circle and the surrounding circles to see if the illusion becomes stronger or weaker.
  * Use different colors or shading for the circles to test if contrast affects perception.
  * Replace circles with other shapes (e.g., squares or triangles) to see if the illusion persists.
  * Present the illusion digitally and allow students to adjust the size of one circle until they believe both are equal, then measure.



====Safety Precautions====
  * Ensure that projections or printed images are clear and visible to avoid eye strain.
  * If drawing by hand, use safe tools (compass, rulers, markers) with caution.




====Questions to Consider====
  * Why does one central circle look larger even though they are the same size? (Because the brain judges size relative to surrounding objects.)
  * How does this illusion demonstrate the role of context in visual perception? (It shows that perceived size is influenced by comparison to nearby objects rather than actual size alone.)
  * Would the illusion still work if the surrounding circles were farther away from the central circle? (The illusion would be weaker.)
  * What real-world examples might relate to this illusion? (Perceiving object sizes in crowded environments, advertising layouts, or optical effects in design.)