Fascinating paper: Your Morals Depend on Language (Costa et al., 2014). People make significantly more utilitarian choices in moral dilemmas when the dilemma is presented in a foreign language, apparently because a foreign language dulls emotional responses and shifts the balance toward deliberative thinking.

It matches my own experience. Thinking in a foreign language feels like rendering graphics without GPU acceleration: everything runs on raw CPU, slower and more laborious. After a full day of conversations in English or Japanese, I'm physically exhausted in a way that Korean never does to me. What I didn't quite register until reading this paper is that the “GPU” doing all that fast, effortless processing is largely the emotional system. When it steps back, you end up doing more of the reasoning yourself. Whether that's a feature or a bug probably depends on what you're deciding.

@hongminhee I have often noticed that it's a lot easier to swear in a second language, because the emotional hurdle is lower. I've always considered that it could be because I wasn't raised in it. Maybe it's a related mechanism.
@julian Yes, that's actually cited in the paper as supporting evidence: swearwords in a foreign language produce weaker physiological responses than in a native one, so it very likely is the same mechanism running in reverse. I personally avoid swearing in foreign languages because I can never be fully sure of the nuance, but I do notice people around me swear more freely in their second languages, which fits the pattern exactly.