I used to think that if you spoke several languages, you could only do one at a time. So, if something interesting happened when you were in French mode, you wouldn't remember it if someone asked you in English. I believed this for a very long time.
A childhood belief about foreign languages

others believed things like this
- At the age of four I believed I was soooo smart. I spoke TWO languages...English AND American!— Melinda
- I used to think that even people who spoke something other than English, thought in English— Peaches
- I thought that people who spoke a different languages were aliens.— Phoebe
- I used to think everyone in the world knew and thought in English, but choose to speak different languages. Anon
- i used to think that french was english backwards!— ---pepsi---
- I used to believe that everybody spoke English in the worldAnon