I know this is true because whenever I watch a movie from my childhood I realize there is an element from the film that was burned into my neural circuitry and when I wasn’t looking it made its way into the pages of my writing. For a concrete example is the warehouse at the beginning of my book Trespassing IS the warehouse from Adventures in Babysitting. Now I only know this because the movie plays a couple times a year on cable. But the minute I saw it, I knew it was the absolute truth.
Armed with my blue pen and journal, no one is safe from my roving eyes. Mannerisms, clothing, and Muni time activities are mine for the taking. You never know how each of these tiny, seemingly irrelevant, bits of information will work its way into your writing. Trust your brain to bring you what you need but writing it down, being intentional with your observations will help too.
Another important directive for writers (and probably tyrants) is: “Your focus determines your reality.” When Qui-Gon Jinn told that to a young Anakin Skywalker it redeemed Phantom Menace for me. But we can talk about that one another time.