Reminded me of something my mother told me about her school years in Finland in around the 60s: In the beginning of the year for the foreign language classes every student had to came up with a fictional persona that fits the culture of the language being learned and stick with it during the entire year.
As I understand one of the main rationales was, that if it less likely for you to fall back to the native tongue when you don't know how to say something when you are playing a role. I found that pretty interesting. I have no idea how widespread this sort of thing is/was.
When I studied French in high school, we started by choosing a French name. It's not necessarily a fictional persona, but it had the same effect on me - I was able to act like (what I imagined to be) a French person, without worrying about how it reflects on my "real" self.
Not sure if related but when i was an ESL student in Canada it was really common to see Asian students using English names as their natives ones are difficult to pronounce, maybe changing your name could play part of it.
As I understand one of the main rationales was, that if it less likely for you to fall back to the native tongue when you don't know how to say something when you are playing a role. I found that pretty interesting. I have no idea how widespread this sort of thing is/was.