This trick is about the color perception, also called the ghost dot, which falls under the optical illusions. This illusion is making the mind perceive things that are not there. It's amazing how the psychology of the mind works. To see other examples check our Brain Tricks main page.
Tips for the color perception: On the right you see a circle of blue-violettish (=magenta) patches, one of which briefly disappears, circling around.
Let your gaze rest on the central fixation cross, but observe with your “inner eye” the patches just when they disappear. With good fixation, you should see a strong greenish colour whenever the violet patch has disappeared.
When you are fixating well, after a few cycles you will actually see a rotating green spot! If your gaze is really steady, the magenta patches will disappear completely, leaving only a rotating green spot (this is easier if you reduce saturation to, e.g., ≈20%); when you then shift your gaze the magenta circle reappears.
Notes: With the “color±” button you can switch to other colours and observe the respective opponent colour. [Remember to fixate for a while because the adaptation to the previous colour subsists for several seconds.] It may surprise you that the complementary colour to red is not green (as mentioned in many textbooks), but blue-green. The colour pickers further down let you explore the full range of colours, including the effect of the background colour.
Trick of the Day: The moon when close to the horizon looks bigger than when it's in heart of the sky. That's because when it's close to the horizon, your eyes sees it in comparison to other parts of the horizon, such as trees, mountains and houses, and that's what makes it look bigger. For more tricks of the day check Tricks of the Day.
Other than the color perception trick, the mind can be fooled in different ways within the subject of the optical illusions. It's no longer accurate to say "what you see is what you get". Now choose a related page, or simply click on previous/ next.