Situating speakers in change: a methodology for quantifying degree and direction of change over the lifespan

Abstract Observations of late adopters catching up with early adopters of language change in a community indicate a potential connection between an individual’s earlier linguistic behaviour and their real-time response to language change. This article provides a means of empirically testing whether such a connection exists, for a given change, by introducing a methodology for obtaining measurements of individuals’ position relative to the change at an earlier time point (a “Cohort Index”) and the direction and extent to which they change over time (a “Difference Index”). Trend and panel data from Australians of Greek and Italian background is used to illustrate both indices for F1 and F2 measurements of fleece, a vowel that has undergone change in Australian English in recent decades. Individuals’ positions in the change for fleece as teenagers are revealed to significantly correlate with the direction and extent to which they have moved in the vowel space over a forty-year period. Specifically, speakers who were originally behind in the change for their generational and ethnic cohort have moved in the direction of change over time more than those who were already ahead. The analysis therefore lays the foundation for the Cohort and Difference Indices to be applied elsewhere.