Optical illusions

Necker rings

Download the optical illusion (PDF, 40KB)

Motion aftereffect

You should see concentric rings, which recede in the video.

Stare at the centre of the rings for about a minute. Then click on the video to pause it, or simply look at anything else. Whatever you look at should appear to expand!

The lilac chaser

A striking illusion based on the colour aftereffect.

If your eyes follow the movement of the rotating pink dot, the dots will remain only one colour, pink. However, if you stare at the black '+' in the centre, the moving dot turns to green.

Now, continue to concentrate on the black '+' in the centre of the picture. After a short period, all the pink dots will slowly disappear and you will only see only a single green dot rotating.

It's amazing how our brain works. There really is no green dot, and the pink ones really don't disappear. This should be proof enough, we don't always see what we think we see.

The graphic is copied from a website of illusions, just for demonstration purposes.

The hollow face illusion

This video shows how a rotating hollow face mask always appears convex.

The video was copied from Yoshida's web page (now offline) for demonstration purposes only.

Colour-contingent motion aftereffect

You should see red stripes moving up, and green stripes moving down.

Stare at the black vertical strip between the the stripes for about a minute. Then click on the video to pause it.

Click on the red/green video to pause it. Look at the black/white video. The upward stripes should now appear green-ish, and the downward stripes should appear red-ish.