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You can make this light shine with the power of your mind. Look at the light bulb for about 20-seconds. Count to yourself, or use the handy timer below. When the time is up, look away from the image to a white area on the screen. You should see a ghostly image of a glowing white light bulb. The after image will fade quickly. After images are caused by tired light receptors in our eyes. After being excited by light from the image, they continue to send weak signals to the brain. These weak after-signals are always in the opposite or complimentary of the original color. What color is the after image of the orange area? Is it Blue?