If you did the suggested experiments, you should have discovered that:
In fact, when doing a raspberry, nothing happens on the computer screen at all. What changes is the way you see the computer screen. Have you ever blinked your eyes rapidly while watching a ceiling fan? If you have, you will have noticed that what ordinarily is a blur of motion can now be resolved into a fan blade that is stopped. This is called a stroboscopic effect ... the same principle is used by a quickly opening and closing shutter on a camera, which 'freezes' the motion of the subject, and allows the camera to capture one instant in time. Although it doesn't look that way, even a simple screen of text on the computer, or a picture on a TV screen, or a solid colour on a monitor, is actually being 'painted' by a very quickly moving beam of electrons. The screen image is actually redrawn by a line moving back and forth down the screen, hundreds of times a second. When you do a raspberry, the vibrations of your tongue cause your whole head (and your eyes) to vibrate. You are trying to look at one spot on the screen, but your focus point is moving away from, and back to, that point ... hundreds of times (?) a second. This causes the stroboscope effect... one or several line being painted on the screen are 'caught in the act' by your vibrating (quickly moving) eyes. Isn't that neat? Now, quick ... go tell those people what you were really doing, before they start a nasty rumour! |