Why do languages tolerate heterography? An experimental investigation into the emergence of informative orthography

Abstract

It is widely acknowledged that opaque orthographies place additional demands on learning, often requiring many years to acquire fully. It is less widely recognized, however, that such orthographies may offer certain benefits in the context of reading. For example, heterographic homophones (e.g., vs. ) impose additional costs in learning but reduce ambiguity in reading. If correct, this would suggest that heterography—and therefore orthographic opacity—might sometimes be selected for in the evolution of writing systems, despite the cost in learning. We investigate this hypothesis by simulating the evolution of orthography as it is transmitted from one generation to the next, both with and without a communicative pressure for avoiding ambiguity. In addition, we consider two mechanisms by which informative heterography might be selected for: differentiation, in which new spellings are created to differentiate words that are homophonous in speech (e.g., from to signal low-fat), and conservation, in which heterography arises as a byproduct of sound change (e.g., vs. resulting from the /ɛː/–/eː/ merger in the Great Vowel Shift). Under pressure from learning alone, orthographic systems become transparent, but when combined with communicative pressure, these systems can become informative, diverging from the spoken language in order to express meaning directly.