When “they” is singular: The interplay between cognitive and social factors predicts pronoun misinterpretations in bilingual English speakers

Language change is shaped by cognitive biases as well as by sociolinguistic perceptions of linguistic innovation. Although the use of they as a singular pronoun to refer to a generic referent is not new in English (e.g., "An employee can file a complaint if they need to"), a recent innovation extends this usage to refer to known individuals of non-binary gender. This type of socially motivated language change allows speakers to position themselves relative to linguistic innovation. Using the self-paced reading paradigm, we examined the processing of non-binary singular they across unambiguous (one-referent) and temporarily ambiguous (two-referent) contexts. We report on a processing experiment with second-language English speakers from Spain who, by virtue of their bilingual experience, are skilled at language learning and regulating activation of competing representations through cognitive control. We investigate how variability in the adoption of the pronominal innovation is influenced by sociodemographic and cognitive factors. We find that seemingly at-chance group-level performance in resolving temporary ambiguities is the product of bimodal distributions in interpretation within the population. Lingering misinterpretations in some speakers are predicted by a combination of sociodemographic and cognitive factors. Critically, we find that even among participants willing to adopt non-binary language, accurate interpretation of the non-binary singular they is mediated by cognitive resources. The findings bear implications for accounts of language change and the adoption of non-binary pronouns in bilingual communities as a result of individual variability. We outline a proposal for a conceptual Integrated Model of Adaptation to Grammar In Evolution ("IMAGINE").