Optical Illusions

These are some really neat optical illusions. Many optical illusions are beautiful, astonishing and powerful. I think they show how easy it is to fool the visual system and the brain.

Same color illusion

In the above image, look carefully at the squares marked as A and B. One appears white and the other appears black, right?

Amazingly, both the squares have the same color! Don’t believe it?

To verify that the color’s are the same, try cutting the two squares and place them side by side in paint or photoshop. Or, you could use the colorpicker tool to check that the colors are the same.

There’s an explanation of why this illusion works at the MIT site.

Scintillating Grid Illusion

This is a famous one. You’ll see the sudden appearance of black dots at the crossings. Also, if you keep your eye fixed on a particular intersection, no dots appear there.

I wasn’t able to find any explanation on how this illusion actually works.

Peripheral drift illusion

The ‘rotating snake’ illusion is one of my favorites. The ‘rotation’ of the wheels occurs relative to your eye movements. It’s thought that asymmetric luminance at the periphery of the vision causes this illusion.

Click on the image to get a larger version of the illusion.

Afterimage illusion

Keep concentrating on the sign at the center of the circle.

Do you see the rotating green spot?

Fraser’s Spiral

Actually, there are no spirals!
The intersecting black arcs appear to form a spiral, but they are in fact concentric circles.

Zollner_illusion

Parallel or not?

External Resources

70 Optical Illusions & Visual Phenomena by Michael Bach
Optical Illusions, Wikipedia