Syntactic priming across highly similar languages is not affected by language proficiency

This study explores the mechanism underlying shared syntactic representations for highly similar languages by investigating whether cross-linguistic syntactic priming is affected by language proficiency. In two experiments, native (L1) Mandarin-Chaoshanese speakers with moderate proficiency in Cantonese (L2) heard Chaoshanese and Cantonese dative sentences with a prepositional object (PO) or a double object (DO) structure, and then completed a description of a depicted ditransitive event using Mandarin. Priming from L2 to L1 was equal to that from L1 to L1, irrespective of whether the prime and the target involved cognate verbs. Similarly, priming from L2 to L1 was not affected by speakers' L2 proficiency, suggesting that shared representations across highly similar languages are insensitive to language proficiency. We interpret the results in terms of the development of shared representations for highly similar languages.