At the height of the Cold War, in the 1960s and beyond, South Korean students were taught — and believed — some startling falsehoods about Communist North Koreans. One of these gained credence and lasted far longer than the Cold War itself.

Over the course of my reporting in Seoul, some interviews with North Korean defectors and older South Koreans have revealed a South Korean notion that North Koreans are really more like ... beasts.

"I once met a senior in South Korea who asked me if North Koreans have horns on their heads," said North Korean defector Lee Gwang-sung, who arrived in Seoul in late 2015. "I said: 'Are we cows? How can we have horns on our heads?' "

Shin Eun-mi, an elderly Korean-American who grew up near Seoul, mentioned something similar in a separate interview.

"When I was in elementary school in South Korea, teachers taught me that North Koreans had horns on their heads like monsters," Shin said.

She eventually realized it wasn't true.

"I knew that biologically, it is impossible for human beings to have horns," she said, "but the demonized images of North Koreans had lingered into my life."

Researchers say the notion of North Koreans — who are the same ethnicity as South Koreans — as being animal- or beast-like is a product of years of propaganda and misleading education.

"It was coordinated from the government. And the political leadership wanted people to believe that North Korea is the biggest enemy in the whole world," says Seoul National University education professor Park Sung-Chung.

North and South Korea were split along an arbitrary line — the 38th parallel— and engaged in a bitter war in the early 1950s before an armistice ended the fighting. The two countries remain technically at war, even today.

"Back in the 1970s, it was about Cold War mentality. We were against any kind of thing that comes from Communism, Communist country," Park says. As to the question of whether North Koreans might have horns, "I never thought that. Maybe when I was in elementary [school], I might have thought that they had horns, but when I was in high school, I didn't believe it."

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.

Park, the education researcher, remembers a hit animated film shown across South Korea when he was a child called Doree Changun. It pits "dorees of courage," witty kids, against evil red wolves, who represent North Koreans.

"This is part of what dictatorships do to mobilize citizens for violence or the potential for violence," Berman says, arguing it's easier to be violent against groups you see as non-human. In other words, if you take away a perceived enemy's humanity, it's easier to fight them. The technique has been used the world over, throughout history.

"It's very difficult, once it's sort of begun, to fight it back," Berman says. "But you know the best way to do that is by letting citizens gain free access to information."

Information about North Korea was especially scarce during the height of the Cold War, says Park.

"We couldn't have any access to North Korea and North Korean people. We didn't have any access to the news releases from North Korea," Park says.

That kind of government censorship hasn't changed. A Cold-War era national security law is still on the books in South Korea — making it illegal for South Koreans to share North Korean content like news reports. The government blocks Internet users from accessing North Korean sites.

The result? Misinformation can live on — as Lee, the North Korean defector, found out.

"I thought, well, we're people, how can we, human beings, have horns on their heads? So I was very surprised and quite weirded out by that," he says of the lingering beliefs.

Even in systems that are considered free, long-indoctrinated beliefs can take generations to change.

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