Take a look at these two photographs. One of them shows a genuine smile; the other shows a fake smile. See if you can spot the fake smile.
Give yourself one point if you chose this photograph. Now try again with these photographs. Here's the correct answer. And finally, try to spot the fake smile here.
If you scored three out of three, then you're good at reading other people's expressions. Two out of three, and you're okay. And if you scored one or zero, then you might want to know the secret to spotting a fake smile.
During the genuine smile, tiny crinkles appear around the sides of the eyes. During a fake smile, these crinkles are missing. So next time you want to know if someone's really happy to see you, simply look at the sides of their eyes.