Acid Trip Illusion


You need to a flashplayer enabled browser to view this YouTube video

When it tells you to look away at the end, look at something with contrast and texture, like with lettering. Not the wall. You can keep looking at the video — the effect you see is in your mind, not in the video.

Illusions: Tricking the Eye or Fooling the Brain?

Optical illusions: caused by eye or brain?

For the past 200 years, researchers have debated whether the illusion of motion in a static image is caused by mechanisms in the eye, in the brain, or by a combination of both. Because measuring these kinds of physiological responses is difficult, no study has successfully measured direct and tightly timed correlations between a kinetic illusion and a physiological precursor.