Optical and visual illusions: the art of fooling our senses

Professor Michael Bach works in the research department at the University Eye Hospital in Freiburg.

Through vision-related pathologies, he has taken a very close look at how the eye works and the different ways to distinguish what really a pathology is from a simple abuse of the senses.

And for abusing our vision, the site "Optical Illusions & Visual Phenomena" is incomparable. You'll find 71 interactive illusions on the site, most of which allow you to change various parameters and thus see how far the illusions hold and the principle involved in each illusion. After about 30 of these, my head was spinning!

Each illusion is accompanied by the necessary explanations: what to look at, what to look for, what parameter to change, etc. Many are amazing, to the point of altering your actual vision for a few seconds and providing food for thought about the nature of our senses, balance included, and their precise adjustment.

The illusions are categorized under headings

• Motion and time
• Brightness and contrast
• Color
• Geometric and spatial illusions
• Space, 3D, and dimensional constancy
• Conditioning effects

71 Optical Illusions & Visual Phenomena