South Korea’s government eventually phased out its “anti-Communist” education program in 1988, replacing it with a more North Korea-friendly “unification” education.

But among some South Koreans, the image of North Koreans as beasts persists decades later. How did it live on for so long?

“It’s very hard to change people’s opinions once they’ve been formed early in life,” says Sheri Berman, a Barnard College political scientist specializing in authoritarian regimes and propaganda.

“The techniques for instilling these beliefs have always been more or less the same. You want to start with children, because they’re the most impressionable and that’s where your belief systems tend to form and stick,” she says.