13/10/2022
It's important to note as well that 3.5-4 is the very very earliest that this skill really develops.
This isn't a moral thing, it's a literal brain skill. There have been studies done where there was no "right" or "wrong", just the rules of a casual game (not even a game with winning/losing). They gave toddlers a series of cards with colors and shapes on them and told them to sort them in a specific way, like "put the red ones here and the blue ones here". The kids were able to do that. Then they switched the rules of the game: "put the square ones here and the circle ones here."
Under a certain age, the children would all continue to follow the first set of "rules". They could repeat the new rule to the tester. They could say out loud that they were supposed to be putting circles here and squares there. But they couldn't make their brains actually make that physical shift.
"But wait a second," you might think. "There's never any two sets of rules. I don't sometimes say 'hit your brother' and sometimes say 'don't hit your brother', so that can't possibly generalize to what my kid is doing.”
You forget: they have a code inside their brain, too. :) Their own impulse is the other set of "rules". Their brain tells them to do one thing -- "he took your toy, get him!!" -- and they might be able to say out loud what the other codified "rule" is, but they can't make their body actually do it.
It's literally a matter of age and maturity and time to grow up enough for their brain to learn how to have one impulse, yet ignore it and choose another. And that's why I say 3.5-4 is the young end of this...that's the age at which the card test starts shifting (to where kids can accurately sort the cards when tested), but that situation has no emotional difficulty involved and it's not a challenging or sudden situation. There are lots of factors that stay in play for many more years to come when kids are struggling to "follow the rules”.
[Image description: A dark blue background with a blue logo of a brain on it. The image reads, “Even when young children have the ability to repeat a rule to you, until they’re about 3 1/2 to 4, they don’t have the impulse control to act on it.” The image is made by ZERO TO THREE, whose logo is also on the image. End description.]
