afterimage
n. the image that remains after a stimulus ends or is removed. A positive afterimage occurs rarely, lasts a few seconds, and is caused by a continuation of receptor and neural processes following cessation of the stimulus; it has approximately the color and brightness of the original stimulus. A negative afterimage is more common, is often more intense, and lasts longer. It is usually complementary to the original stimulus in color and brightness; for example, if the stimulus was bright yellow, the negative afterimage will be dark blue.