Disclaimer before I go any further: I know almost next to nothing about language acquisition and development. This is simply an opinion I have formed as a non-native speaker of English, and as a foreigner living in Texas.
I have been here 10 years now, and I have not forgotten my native tongue. I think in Romanian ALL THE TIME, especially when I’m upset or intoxicated. It’s just how it is. Interestingly enough, and as a side note, I dream in English when I’m here and in Romanian when I’m home. Fascinating, isn’t it?
I never forgot the rules of grammar, the conjugations (and there’s lots of those, like in French… a nightmare for anyone trying to learn Romanian), the articles, the plurals, the feminine/masculine/neutral nouns (Yes, we have neutral nouns in my language). I never forgot our folk stories and legends, or the idioms and slang I learned growing up. I didn’t forget the words for milk, thirst, bathroom, drink, meal, etc., etc. I didn’t forget when to use formal address and appropriate greetings, or words of appreciation and disgust. I do have issues sometimes with technical terms, especially those related to psychology. This is because I never studied psychology back home (I think), so I generally have to look up Romanian equivalents for terms like working memory, curriculum based assessment, functional communication, mand, tact, fluid reasoning, academic fluency, broad written language, psychopatic deviate and many more.
I only speak Romanian on Sundays, for maybe 20-30 minutes (it’s my weekly phone call with my mom). But I never have any issues speaking when I go back home. I was told there’s a slight accent for the first couple of hours I’m there, and then it’s gone and everything’s back to normal.
The point is that I don’t believe you can actually forget so much of your own language if you don’t use it. Some members of my family spent a few years in Canada and when they went back home, they mixed English and Romanian like crazy. Honestly, it just made them look stupid, and I was so tempted to tell them as much because they thought it made them seem interesting (and above everyone else, which they enjoyed thoroughly). Let’s assume you’re under some distress and forced to not speak your language for a long period of time. Even so, you still have your THOUGHTS. And no one can force those to be in a different language. So, then, how do you forget?
I just don’t get it. I wish someone would explain it to me, because I just don’t get it. If anyone knows of any research on this topic, please point me in that direction. A scientific explanation might make change my mind about this.