1. Stare at the red dot on her nose for 30 seconds.
2. Turn to face a blank, light coloured surface (ceiling or wall).
3. Blink repeatedly and quickly.
4. Now... what do you see?
- Visit "Museo de las Ilusiones Ópticas" en Barcelona.
- Interactive optical illusions.
- Practice optical illusions with educacionplastica.net. (Spanish)
- Color and contrasts with educacionplastica.net. (Spanish)
- Everything about optical illusions.
- More optical illusions.
- 95 Visual Phenomena and Optical Illusions.