[POS] Other disciplines

[POS-69] Peripheral linguistic pattern can emerge even when new words are innovated not only in a cultural center but also in peripheral areas

*Seo Hachimaru¹, Motohide Seki¹ (1. kyushu university (Japan))

Keywords:

language evolution,cultural transmission,Bayesian inference,agent-based simulation

Languages evolve through diffusion processes similarly to biological evolution, forming linguistic clusters based on geographic proximity. Recently, several mathematical modeling studies have tested a theory of linguistic diffusion that assumes two conditions: that new words are innovated solely at a cultural center (centralized neologism creation) and that these words spread outward due to the prestige of the cultural center (center prestige), resulting in a concentric distribution of words. However, real-world cases show that innovations can also originate in peripheral regions. To examine how these two assumptions relate to patterns of linguistic distribution, we extended the Iterated Learning Model (ILM) to include multiple agents, which correspond to geographically distinct subpopulations of a nation, per generation. Each agent receives data from agents in the previous generation according to the probabilities described by the connectivity matrix and guesses the frequency of each word using Bayesian inference. We implemented a one-dimensional lattice structure in which each agent exchanges data only with neighboring agents, thereby modeling geographically constrained transmission pathways. Through the repetition of this process across generations, linguistic change is simulated. Using the model, we examined whether and how the two key conditions, the centralized neologism creation and the center prestige, influence the formation of a concentric distribution. Simulations revealed that concentric linguistic distributions can emerge not only when both conditions are present but also when one of the two is absent. These results challenge the assumption that both conditions are necessary for the concentric distributions. According to the analytical solution of word age, the centralized neologism creation leads to the retention of older words in peripheral regions, which pattern has been often reported in empirical studies. Without the centralized neologism creation, the age of words will be constant across all subgroups. If both the centralized neologism creation and the center prestige are present, the age of words increases linearly with the distance from the cultural center. The present model thus indicates that the satisfaction of one or both conditions in a population can be predicted by investigating the word age distribution there.