Published online by Cambridge University Press: 28 November 2008
Although variationists have explored the diffusion of linguistic changes from one social group to another and from one linguistic environment to another in some detail, they have done much less work on the spatial diffusion of changes. In fact, Trudgill's (1974, 1975) use of Hagerstrand's gravity model to explain in hierarchical diffusion of innovations in East Anglia and Norway was the only systematic account of spatial diffusion in the literature. This article uses data from the random sample telephone survey portion of a Survey of Oklahoma Dialects (SOD) to explore the spatial diffusion of linguistic innovations in Oklahoma. It analyzes that data using a variety of techniques of computer cartography and the General Linear Models procedure in SAS. The data clearly show that, whereas some linguistic innovations diffuse hierarchically (as linguists have long contended), others diffuse contrahierarchically, while still others diffuse in complex patterns that show characteristics of both contagious and hierarchical diffusion. An analysis of the barriers to and amplifiers of diffusion suggests that these different types of diffusion are a consequence of the different social meanings that linguistic forms carry.