Just remembered that very small children can't conceptualize the idea of a False Belief and idk why that's throwing me all of a sudden but omg what the hell
A False Belief is just a perception of reality based on available evidence, prior knowledge, and logical reasoning. The most famous example showing how children have yet to aquire it goes like this:
A small child is shown a labeled box of candy. The researcher will ask "what's in the box?", and the child will say "candy". Then the researcher will open the box, and reveal that the box is filled with marbles. The research will ask "what's in the box?" and the child will say "marbles".
Then, the researcher will ask "if I show this box to mommy, what will she think is inside?" And the child will say "marbles", not "candy". When pressed, a child will maintain the reasoning that their mom will expect the candy box to have marbles inside, even though there's no reason to.
"Why would Mommy think there's marbles inside? "Because there is marbles inside!"
Even though all evidence and prior knowledge would point an older person to assuming there's candy inside, and even though that child themselves also made the assumption that there was candy inside, the child cannot conceptualize the idea of their mother operating without the amount of information that they have themselves. They know that there's marbles inside, so how could anyone else expect there to be candy?
"How long do they think like that?" Until they're about 5ish.
"Oh, then how do they figure it out?" Who fucking knows!
(I'm being dramatic, we do know that it's the inevitable result of several other intellectual skills developing, but still. Then we get into the discrepancies between what causes people to develop things like this or not! It's fascinating~)