The Poggendorff Illusion is an optical illusion that involves the brain's perception of the interaction between diagonal lines and horizontal and vertical edges. It is named after Johann Poggendorff , who first described it in 1860.

In the picture to the left, a straight black line is obscured by a red rectangle. The black line appears disjointed, although it is in fact straight; the second picture illustrates this fact.

External links

• Poggendorf Illusion
• Circular Poggendorf Illusion
• Poggendorf Illusion
• Explanation of the Poggendorff, Hering, and Zoellner illusions