Ruth's Waterfalls
of the Finger Lakes, Rochester, and Ithaca, NY.

What's New

Waterfall Illusion

We've read about the "Waterfall Illusion" and seen demonstrations in museums and on the Internet, but we didn't really appreciate it until we saw it at a real waterfall—the Upper Falls of the Genesee River in Rochester, NY. Since then, we have noticed this illusion at lots of smaller waterfalls and have found lots more information on the Internet.

The Waterfall Illusion is also known as the motion after-effect illusion. If you stare at a waterfall for about 20 seconds, when you then look at a stationary object, the object seems to be moving in the opposite direction.

Here is a simple demonstration you can try for yourself:
Move the pointer onto the right scroll button at the bottom of the text box. Hold the mouse button down to scroll the message to the right while you read the remainder of the instructions.

(Sorry, this may not work with Macintosh IE.)

For even more amazing demonstrations and an explanation of why this happens,
visit the following web pages:

But do get out and stare at a real waterfall for a while!

Here are some other illusions we like a lot.