Abstract

Objects in nature often have symmetrical shapes. Many scripts derive from iconographic representations and therefore contain symmetrical letters (intrinsic symmetry). On the other hand there are scripts which contain letters that are the symmetrical counterpart of another letter (such as b-d and p-q). This is called extrinsic symmetry. Scripts are subject to similar conditions of perception as in the perception of space. The following research shows how object constancy is involved in the evolution of scripts. Object constancy is the ability of the brain to recognize objects in 3D space, independent of their orientation. The shape and its mirror image are connected with the same association. A script including letters whose mirror images are connected with a different meaning or sound representation should be less readable because object constancy gives both letters the same association. The study tests the assumption of lower readability in proving an avoidance of extrinsic symmetry. For this purpose a new method in measuring symmetry is used. The examination compares and illustrates symmetry properties of different scripts and shows the following results: Scripts suppress perfect symmetry between two characters by using additional distinctive features. Invented scripts (such as scripts for secret messages, functional scripts and those which are invented for a story) in contrast to widely used scripts are usually not bound to readability. They can therefore use symmetry to create new characters. Such a font is economical with regard to shape variability, and produces an aesthetic and homogeneous impression.