Someone here will probably know this better than I do (unfortunately :( ), but I believe there have been a series of studies done on the interplay between language and culture within certain countries--that certain constructions within the language allow for the development of differing types of cultural standards. The example that is coming to my mind is a language like German when compared to English. In English, you tend to be able to interrupt people more often, because you know where a sentence is going (You can go fuck--), whereas in German (I believe), since verbs come at the end (you yourself can go fuck--I know this isn't how it would be set up exactly), you can't interrupt nearly as much. Perhaps there is some ground in the idea that since learning languages forces you to subconsciously accept new modes of communicating, your way of looking at rational choice changes.

Of course, there's probably also an effect of simply needing to be more rigorous in a language that's not your own. My ability to be lazy in English is in part because I've spent a lot of time in this language and feel comfortable assuming things that I probably should not be. Whereas if I began to learn Mandarin, I would have to think about everything I say and do.