A quick Google search for "L1 attrition file:pdf" or "first language attrition file:pdf" returns tons of results, so it doesn't seem to be that understudied. I

A quick Google search for "L1 attrition file:pdf" or "first language attrition file:pdf" returns tons of results, so it doesn't seem to be that understudied. I think it mostly depends on what you want to focus on: do you want to know how a specific language or group of languages come to be lost by native speakers (e.g., indigenous languages)? Or are there some linguistics characteristics that you're more interested in analyzing (e.g., writing attrition, phonological attrition, grammar attrition)? Here are some the things that I found; I can't guarantee they're all scientifically sound though, you'll have to do your own checks: [1] Schmid, M.S. 2011. Language Attrition. Cambridge: Cambridge University Press. https://www.cambridge.org/core/books/language-attrition/E01D99C677868227CED2DEB9E35E5E56 https://www.cambridge.org/core/books/language-attrition/E01D... [2] Gallo et al., First Language Attrition: What It Is, What It Isn’t, And What It Can Be (December 23, 2019). Higher School of Economics Research Paper No. WP BRP 113/PSY/2019. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3508640 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3508640 [3] Francis, 2023. When does second language learning lead to first language attrition? https://www.researchgate.net/publication/365372235_When_does_second_language_learning_lead_to_first_language_attrition https://www.researchgate.net/publication/365372235_When_does...