Introduction Look in a mirror.
Here are a few experiments you can do to isolate several of the many clues your eye-brain system uses to determine the distance to an object or an image. When you look directly at an object, the visual clues usually agree with each other and all suggest the same location. However, for an image a variety of contradictory clues can suggest different locations for the image. For example, the rule that near objets obscure far objects suggests that an image must be located on the surface of a mirror while the different images seen by our two eyes suggest that the image is as far behind the mirror as the object that made the image is in front. Different people may thus perceive an image made by a mirror to be located in different places.