Smooth signals and syntactic change

A large body of recent work argues that considerations of information density predict various phenomena in linguistic planning and production. However, the usefulness of an information theoretic account for explaining diachronic phenomena has remained under-explored. Here, we test the idea that speakers prefer informationally uniform utterances on diachronic data from historical English and Icelandic. Our results show that: (i) the information density approach allows us to predict that Subject and Object type will affect the frequencies of OV and VO in specific ways, creating a complex Constant Rate Effect, (ii) the bias towards information uniformity explains this CRE and may help to explain others, and (iii) communities of speakers are constant in their average target level of information uniformity over long periods of historical time. This finding is consistent with an understanding of this bias which places it deep in the human language faculty and the human faculty for communication.