Personally I also remember (as a child) thinking that the US had 52 states but that's mostly because "51st state" is a common expression I likely came across frequently enough to think that there are at least 51 states, 50 feeling too rounded and 52 being a close enough number that frequently pops up elsewhere (52 cards in a deck, weeks in a year).
I don't like the term "Mandela effect" because of the pseudo-scientific connotations, though. It's just a false memory and in many cases it's not even a memory, just a misconception (like thinking there are penguins at the North Pole because it's easy to mix up the Arctic and Antarctic or to mistake puffins for some kind of penguin).
EDIT: As for Korea: googling yields several claims of people misremembering its placement on the map but if I had to guess I'd blame news reports that like to highlight countries on the map by showing them in isolation or exaggerating their borders by creating a small gap around them.
Personally I also remember (as a child) thinking that the US had 52 states but that's mostly because "51st state" is a common expression I likely came across frequently enough to think that there are at least 51 states, 50 feeling too rounded and 52 being a close enough number that frequently pops up elsewhere (52 cards in a deck, weeks in a year).
I don't like the term "Mandela effect" because of the pseudo-scientific connotations, though. It's just a false memory and in many cases it's not even a memory, just a misconception (like thinking there are penguins at the North Pole because it's easy to mix up the Arctic and Antarctic or to mistake puffins for some kind of penguin).
EDIT: As for Korea: googling yields several claims of people misremembering its placement on the map but if I had to guess I'd blame news reports that like to highlight countries on the map by showing them in isolation or exaggerating their borders by creating a small gap around them.