APA Dictionary of Psychology

n. the altered perception of a sensory stimulus that results from prolonged exposure to another stimulus. Aftereffects are often visual and are usually the inverted form of the original stimulus. For example, viewing a pattern of lines tilted to the left will make a pattern of vertical lines appear to be tilted to the right (the tilt aftereffect; TAE). There are various other types of aftereffects, including the contingent aftereffect and the motion aftereffect.