OpTiCaL IlLuSiOnS

Here you'll learn about one of my interest, optical illusions. Optical illusions have many different types and forms. This site shows almost all the various types.

The topic of Optical Illusions has been found within numerous texts and publications of many different fields due to the wide area of its application. Biologists studies how optical illusions are perceived by human eyes and brain

An optical illusion is any illusion that deceives the human visual system into perceiving something that is not present or incorrectly perceiving what is present. There are physiological illusions and cognitive illusions.

Optical illusions can occur naturally or be demonstrated by specific visual tricks that show particular assumptions in the human perceptual system.

An optical illusion. Square A is exactly the same
shade of grey as square B.
For more information click on the picture
Larger version

A mirage is an example of a natural illusion that is an optical phenomenon. The variation in the apparent size of the Moon (smaller when overhead, larger when near the horizon) is another natural illusion; it is not an optical phenomenon, but rather a cognitive or perceptual illusion.