I knew a boy in first grade who didn't think people from England spoke English. As best I can figure it, he figured that accents qualified as other languages.
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 everyone in the world knew and thought in English, but choose to speak different languages. Anon
- I thought that people who spoke a different languages were aliens.— Phoebe
- I used to think that even people who spoke something other than English, thought in English— Peaches
- I used to believe that, no matter what language other people spoke, that everyone thought in EnglishAnon
- I used to believe that everybody spoke English in the worldAnon