Are non-native speakers the drivers of morphological simplification? A Wug experiment on the Dutch past tense system

It has often been suggested that there is an inverse correlation between the number of adult non-native speakers in a language and its morphological complexity. Secluded languages often show more complex morphology, while high-contact languages go through more severe simplifications throughout the ages. One such simplification linked to language contact is the regularization of the Germanic past tense. Yet, a Wug task on the English past tense system by Cuskley et al. (2015) showed that non-native speakers tend to use the irregular past tense even more than native speakers. In this paper, we replicate the Wug experiment for Dutch. Our results show similar evidence for a higher rate of irregularization across non-native speakers. Furthermore, we do not find any other simplification strategies among non-native speakers. Though caution is warranted, these converging results may suggest that non-native speakers are not the drivers of morphological simplification.