Natalie Portman and Keira Knightley look identical. Can't see it? Well, go back and watch Star Wars: Episode I The Phantom Menace. Actually, don't do that. It's not a great movie. But Knightley played the decoy for Portman. If you still can't see it, then you have something in common with these Korean people.
In the video by sw yoon, a group of Korean men and women are presented with multiple photos of popular Western celebrities and asked to match up the photos that depict the same person. The task proves difficult because people can't recognize subtle differences in other ethnicities due to what's called cross-race effect.
In this instance, these Korean people can't tell a Zooey Deschanel from a Katy Perry, (OK, no one in America can, either) and after 30 attempts, the group gave only three correct answers, demonstrating that there's something to the cross-cultural failure to recognize faces unlike your own.