Victor Mair has an interesting post at Language Log:
...a loyal Language Log reader sent in the following observation this morning:
While in high school in England, I had a Swedish girlfriend who used to switch back & forth between Swedish, English, and French when talking with her sister. I asked her “Why do you do that???” and she said, “it’s just easier to say something in one language than another.” Notably, she got the best grade in our English class.I would simply like to say that often my thoughts will be in different languages, depending what it is that I'm thinking about. Or I'll be talking in English and want to say something in Mandarin or in Japanese. Or I'll be speaking Mandarin and it will seem more suitable to say something in another language, such as Cantonese or Taiwanese. As to why I do that, my best guess is that it feels better to say something in one language than in another. With effort, I can probably say just about anything I want to get across in any of the languages I know, but it is easier and more efficient to say certain things in one language than in another.
There are eleven comments so far, some quite interesting. Code switching seems common among multilinguals. One HomerM offers this amusing observation that speaks to the power of context:
Just an added thought. I learned to ski in French. When I returned to the U.S., I was totally unable to communicate in an American ski shop.