Although personality-related factors play a crucial role in sociolinguistics as conceivable sources of language variation and change, there is insufficient quantitative evidence on such relationships. Using a large and balanced sample (n = 1000), this study investigated effects of personality traits on the use of a Swiss German plural marker in its early stages of diffusion. Besides age and region, conscientiousness and extraversion emerged as the most important predictors: less conscientious and, to a certain extent, more extraverted speakers were more likely to contribute to the diffusion of the morphological innovations under investigation. Based on our results, we argue that less conscientious speakers might monitor their own speech and that of others less closely, thus adopting innovations earlier, whereas extraverted speakers may act as successful brokers in transmitting innovations from one social group to another.
