Thinking in a foreign language is essentially a form of visualization or rehearsal that prepares you for the real deal (an actual conversation). With visualization we can go through the steps of making an attempt, to identifying a mistake, to correcting it in a very short period of time. In other words, the feedback loop is very tight. As researcher Kathryn Schulz points out in this TED video, being wrong is quite normal and perhaps even good – as long as you become aware of your mistakes and correct them when possible.