What language do you think in?
I don’t think in any language. I think in images. I don’t believe that people think in languages. They don’t move their lips when they think. It is only a certain type of illiterate person who moves his lips as he reads or ruminates. No, I think in images, and now and then a Russian phrase or an English phrase will form with the foam of the brainwave, but that’s about all.
From Vladimir Nabokov’s 1962 interview to BBC Television as published in Strong Opinions1973.
(This quote came to my mind when I saw the NPC meme. It turned out others had drawn the same parallel. The meme now has a strangely detailed Wikipedia article.)