There's supposedly a study (I saw someone mention it in a Youtube video) where some unspecified military needed to find hidden tanks when looking at a battlefield. There were two people who were much better at this than everyone else, so there was a study done on how they did it, and they wrote an in-depth report on their methods. But eye tracking software showed they were actually doing it a totally different way from their description. The lesson being that people don't always consciously know how they perform a particular cognitive task.

I cannot find any original source for this. Resolves YES if anyone provides me one, NO at close if no one does, N/A if I manage to find it myself.

Intermediate sources (like someone else repeating the story without saying where they got it) are not sufficient to resolve YES but would certainly be useful clues, so please share any you know of.