Reliable Detection and Quantification of Selective Forces in Language Change

TL;DR

This paper introduces a method to quantify the strength of selective forces in language change, demonstrating its reliability and interpretability through case studies on English verbs and Spanish spelling reforms.

Contribution

It applies a novel, reliable method to measure selection in language change, extending its use to phonological and social influences in historical corpora.

Findings

Bias towards phonological simplicity can override grammatical simplicity.

The method detects changes in selection strength over time.

Quantitative testing of language change mechanisms is feasible with corpus data.

Abstract

Language change is a cultural evolutionary process in which variants of linguistic variables change in frequency through processes analogous to mutation, selection and genetic drift. In this work, we apply a recently-introduced method to corpus data to quantify the strength of selection in specific instances of historical language change. We first demonstrate, in the context of English irregular verbs, that this method is more reliable and interpretable than similar methods that have previously been applied. We further extend this study to demonstrate that a bias towards phonological simplicity overrides that favouring grammatical simplicity when these are in conflict. Finally, with reference to Spanish spelling reforms, we show that the method can also detect points in time at which selection strengths change, a feature that is generically expected for socially-motivated language change. Together, these results indicate how hypotheses for mechanisms of language change can be tested quantitatively using historical corpus data.