Is the Red Ruler really the same size as the Blue Ruler?

Which ruler is longer, RED or BLUE?

Drag them to different positions to see for yourself.

The Jastrow illusion is an optical illusion attributed to the Polish-American psychologist Joseph Jastrow.

This optical illusion is known under different names: Ring-Segment illusion, Jastrow illusion, Wundt area illusion or Wundt-Jastrow illusion, and Boomerang illusion.