Mechanisms of sub-phonemic change in prescriptive bilingualism: The case of Mexican Plautdietsch

This paper investigates the relationship between loanword adaptation and phonological borrowing by looking at the Mexican Plautdietsch speech community. Plautdietsch borrowings from Mexican Spanish sometimes undergo loanword adaptation to fit the native phonological system (e.g. Spanish [peso] > Plautdietsch [pəɪzo] 'peso'), but some community members exhibit a borrowed pattern of deaffrication that targets native lexical items (e.g. [dit͡ʃ ]) 'German' > [diʃ]). I show that the output of /t͡ʃ/ deaffrication in Mexican Plautdietsch follows the phonological pattern of northern Mexican Spanish deaffrication, rather than an inherited pattern that adapts loanwords from High German and Russian. I propose that while some mechanisms of phonetic and phonological interpretation are similar for both loanword adaptation and phonological borrowing, the novel Mexican Spanish pattern could have only entered the community due to the unique structure of phonological representation associated with advanced bilingualism. This prediction is borne out in the social distribution of deaffrication wherein men, who are expected to become advanced bilinguals, exhibit the innovation more than women. By adding a dimension of phonological representation to our models of loanword adaptation, we can expand the model's behavior to also account for outcomes involving the restructuring of the heritage language.