1. Instant Gratification

This one works immediately – stare at the dot in the center of the image and move your head back and forth – the rings will rotate.

2. Leaning Tower Illusion

The two images above are identical, yet the tower on the right appears to be leaning more steeply. The reason for this is because the visual system treats the two images as if part of a single scene. Normally, if two adjacent towers rise at the same angle, their image outlines converge as they recede from view due to perspective, and this is taken into account by the visual system.

3. Straight Lines

The image above is composed entirely of straight lines. If you don’t believe, try using a ruler to test it.

4. Inverse Image

Stare at the center of the image above for about 30 seconds then immediately look at a blank white wall or a piece of white paper. Stare at the blank paper and an image will emerge. The more you stare, the clearer the image becomes.

5. Sacred Heart Illusion

Click the image above to open it as its full size then slowly move your head away from the image.

6. Color Illusion

This one is amazing – the blue and green lines in the picture above are the same color.

7. Impossible Cube Illusion

The impossible cube or irrational cube is an impossible object that draws upon the ambiguity present in a Necker cube illustration. An impossible cube is usually rendered as a Necker cube in which the edges are apparently solid beams. This apparent solidity gives the impossible cube greater visual ambiguity than the Necker cube, which is less likely to be perceived as an impossible object. The illusion plays on the human eye’s interpretation of two-dimensional pictures as three-dimensional objects.

8. Ebbinghaus Illusion:

The Ebbinghaus illusion is an optical illusion of relative size perception. In the best-known version of the illusion, two circles of identical size are placed near to each other and one is surrounded by large circles while the other is surrounded by small circles; the first central circle then appears smaller than the second central circle.

9. White Illusion

White’s illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contexts. Note, that although the gray rectangles are all of equal luminance, the ones seen in the context with the dark stripes appear brighter than the ones seen in the context with the bright stripes.

10. Color Perception

Believe it or not – the pink spots in the image above are the same – if you don’t believe it, open the image in photoshop and compare them.

• January 29, 2009 -- Some Stunning Optical Illusions (Part I) (1)