Reflections on inversion and reversion.Perception. 1993; 22(7):863-8.P
A paper published recently in Perception has drawn attention to a question that appears to mystify psychologists, yet yields simply to the well-known law of reflection. The question of why a mirror reverses left and right, but not up and down, is explained in this paper, in terms of physical optics. The question of how mirror-reflected objects are perceived remains, of course, a psychological one.