Not just code-switching

A large number of linguists are interested in code-switching or any other kind of mixing of languages. Their studies illuminate many aspects of language use. For example, studies of Finglish (Finnish + English) have shown that speakers do not just shift languages out of lack of competence in one or the other language, but because the idioms are different. Idioms are based on ways of thinking about reality, so it is the way of thinking that is different.

Here, for example, is how Anne Putkuri describes the experience of mixing languages: "If you can't find a Finnish word, you quickly replace it with an English one. The word may be English, but you use the inflection rules of Finnish. I do word-for-word translations myself, too; I do the dishes, and I don't seem to be able to learn that in Finnish one washes the dishes."

Writers are even more precise in their choice of languages to mix or to use in a second-language or mixed-language text. The difference between do and wash is major for a poet (they do not rhyme, for instance); the choice is dictated by aesthetic, instead of just mere linguistic reasons.