common examples of mental images include daydreaming and the mental visualization that occurs while reading a book. another is of the pictures summoned by athletes during training or before a competition, outlining each step they will take to accomplish their goal. when a musician hears a song, he or she can sometimes "see" the song notes in their head, as well as hear them with all their tonal qualities. this is considered different from an after-effect, such as an afterimage. calling up an image in our minds can be a voluntary act, so it can be characterized as being under various degrees of conscious control.