Background

The "rotating snakes illusion" was originally created by Akiyoshi Kitaoka as a demonstration of peripheral drift, and has since been subject to many alterations and variations. Whilst it is commonly called the snake illusion, it can also be called the "automatic rotating circles", and to give its scientific title, a demonstration of "anomalous motion".

What is the optical illusion supposed to show?

The rotating snakes illusion is supposed to show - in its simplest form - oscillation of a circle or set of circles when no movement takes place. If that sounds too sciency for you then don't worry. Shortly, it supposedly makes the brain show something as moving when it actually isn't.

How can I make the illusion occur?

Look at the collections of shapes in each image, and the results are immediately apparent. If you struggle to the see the illusory movement, try the image from a distance, and concentrate solely on the whitespace around the main image content. Without directly looking at the mass of colour, you should notice the illusion.

Images

Below are three versions of the "Rotating Snakes". Click on each for an enlarged view of the optical illusion:

How does it work?

The workings of this illusion are too complex to be worth describing here. The science behind it would take pages of detail, and to be frank, I do not think is worth typing. If you are interested in the inner workings, I refer you to this .PDF file produced by Hiroshi Ashida and Akiyoshi Kitaoka.