One simple trick for keeping multiple languages distinct in your mind

If you are learning your third or fourth (or fifth, sixth, seventh...) language, keeping them straight in your head can be daunting. Here's a simple trick that I think will help you compartmentalize learning and using new languages. I used to have trouble resetting to the local tongue when arriving in a new destination. Usually I could understand sufficiently but my first responses would come out uncontrollably in a totally different language.  I'd even visualize the response in the wrong language. It's hilarious but ultimately useless to speak to passport control in Spanish when landing in PVG. As an aside, my fall back language when I'm first adapting or dead-dog jetlagged is almost always Spanish, my second language. To overcome this, I developed a mental exercise to compartmentalize languages by associating each with a specific color. This works well for me for two reasons. First, the process is deliberate and places one in a mental state focused on retrieving a specific subset of knowledge. Second, I'm a grapheme-color synesthete and already associate colors with letters, words, and sometimes sounds. This experience is even more a cute for me when learning and recalling vocabulary of foreign languages. In practice, my process works something like this: En route, I review my language notebooks and listen to recorded dialogue and language lessons. While doing this, I meditate on the associated color sometimes with a small print out or colored sheet of paper in front of me corresponding to the language to further strengthen the association. Later, I will do guided meditations / yoga nidras focusing on the appropriate color, eyes closed. For reference, here are my current color <-> language associations. Spanish : red French : blue Portugese : green Japanese : gray Thai : yellow Mandarin : purple Do you have any tricks for keeping languages distinct in your head? I'd love to hear them!