Fechner Color Illusion #1 (linear motion)

	Fechner #1 Applet (below) doesn't work even though you installed Java?
	Run the Fechner #1 Web-Start Application instead.
	This downloads a jnlp (Java Web Start) file that tells Java how to run the Fechner #1 outside of your browser.
	See my Java Web Start notes.

Perceive color where there is only black and white.

See also:
Fechner Color Illusion #2
(rotating)

More Java applets here.

This is a Java 1.1 applet. See my Java page for Browser Requirements.

The Illusion:

The moving pattern is drawn with black on white. But if you stare at it without letting your eyes follow the motion, you will probably see a faint illusion of color. Part of the pattern appears to me to be dark brown with yellowish edges. Another part appears purplish. Different observers may see other colors.

Click the Stop button to see the true black and white.

Experiment to see what speed gives the strongest effect (use the slider control).

Click the Reverse button to reverse the motion. The colors switch.

Notes:

This animation is very effective for inducing motion sickness (similar to the movie "The Blair Witch Project"). If you start to feel nauseous, take a break from it.
You can use the Detach button to detach the applet into its own window. Then you can resize it. However, large window sizes don't work very well on a slow computer.
The behavior of the Speed Slider may be discontinuous for higher settings. Above a certain point the animation delay is less than 18 milliseconds -- the clock resolution of many computers.

What Other People Saw:

Go to Fechner Illusion Guestbook

Credits:

I learned about this illusion (in its rotating form) from the "Amateur Scientist" article by C. L. Stong in the March 1971 issue of Scientific American magazine (Stong01).

Stong says: "The experiment was devised by the German experimental psychologist Gustav Theodor Fechner."

After writing the rotating version, I realized that rotation is not required. So I wrote the "linear motion" version on this page.

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