The Andrus Spiral Illusion

was built by Mark Newbold and is named after its inventor, Jerry Andrus.

It is said that Socrates discovered this effect while staring at a waterfall 2-thousand years ago.

Look at the moving patterns in the spiral for 25-30 seconds, or long enough to charge up your light receptors. Now look at your hand, or a friend, or at this paragraph. You will see the “boiling effect” in the air before your eyes for a few seconds. Use the control panel to program the spiral.

The “boiling effect” spiral illusion demonstrates a phenomenon called complementary afterimage perversion. In this case, it means that if you stare at high contrast, moving patterns your mind’s eye can “remember” the movement for a few seconds afterwards.