The Beta movement is an optical illusion, first described by Max Wertheimer in 1912^{[citation needed]}. Its illusion is that fixed images seem to move, even though of course the image does not change. It might be considered similar to the effects of animation. Wertheimer wrote his paper in the early days of motion pictures, and this may account for some of his findings, as people were unfamiliar with images moving at all.

Of course the static images do not physically change but give the appearance of motion because of being rapidly changed faster than the eye can see.

This optical illusion is caused by the fact that the human optic nerve responds to changes in light at about 10 cycles per second^{[citation needed]}, so changes about double of this are registered as motion instead of being separate distinct images.

One example of the beta movement effect would be a set of LEDs, as shown at the picture on the right. The LEDs, electronically, are individually controlled, but our eyes and brains perceive them as a snake running clockwise around the four edges of the square picture. This is also seen commonly on LED writing boards.