Left and Right in Science and Art

An asymmetric object can exist in two left-right mirror-image forms, enantiomorphs, a phenomenon which has fascinated philosophers, cosmologists and artists. Psychologists and neurophysiologists have been particularly puzzled by the extreme difficulty children and other animals have in learning to distinguish left-right mirror images. The authors propose an explanation of why mirror images are so confusing. In the natural world almost all mirror images are actually two aspects of the same object, for example, the two sides of a face or a silhouette viewed from the front and back. Therefore a perceptual mechanism that treats mirror images as equivalent would be adaptive. The perceptual equivalence of mirror images only becomes maladaptive or confusing under very special conditions. One of these is learning an orthography containing mirror images such as b and d. Difficulty in learning to read, may, in part, be due to difficulty in overcoming the normal tendency to treat mirror images as the same stimulus.

In the final portion of the paper the authors consider the effects of mirror-reversing a painting and, more generally, left and right in pictorial space. They suggest that some pictorial anisotropies, such as profile orientation, reflect the influence of lateralized brain functions, whereas others, such as the tendency to look at a picture from left to right, are cultural conventions.