I noticed an interesting phenomenon when I was learning my 3rd language. Whenever I was struggling to find a word in the newest language, I was more likely to

I noticed an interesting phenomenon when I was learning my 3rd language. Whenever I was struggling to find a word in the newest language, I was more likely to confuse it with a word in my 2nd language than with my 1st. For some reason, my brain had assigned language #1 as "primary" and then all subsequent languages as "secondary" leading to sometimes substituting words from one to the other under duress.