美国国家公共电台 NPR The Science Of Smiles, Real And Fake（在线收听）

STEVE INSKEEP, HOST:

Just to let you know, I'm smiling right now. In theory, this is good for me. And smiling can be good for you. Back in the 1800s, Charles Darwin suggested that smiling could improve your mood, and that idea is still taught in psychology class. But researchers are now finding this phenomenon is more complicated than they thought. Maanvi Singh reports.

MAANVI SINGH, BYLINE: Scientists call it the facial feedback hypothesis. Here's Dick Van Dyke explaining how it works.

(SOUNDBITE OF SONG, "PUT ON A HAPPY FACE")

DICK VAN DYKE: (Singing) Gray skies are going to clear up. Put on a happy face. Brush off the clouds and cheer up. Put on a happy face.

SINGH: The idea is, physically expressing an emotion intensifies the feeling. So if you smile, you feel happier. If you frown, you feel angrier.

NICK COLES: This has sort of been a textbook psychological phenomenon.

SINGH: That's Nick Coles, a social psychologist at the University of Tennessee, Knoxville.

COLES: I feel like a lot of people have heard at one point in their lives that they can smile their way to happiness, but psychologists have actually disagreed about this for, really, over a hundred years - since the dawn of psychology, really.

SINGH: So Coles decided to analyze 50 years of data, including nearly 300 separate experiments that tested the facial feedback theory. He and his colleagues found that smiling did increase happiness, but only a tiny bit. The data suggests that if 100 people smiled, only about seven would experience that mood boost.

COLES: These effects are extremely tiny. They're fascinating from the scientific perspective.

SINGH: Coles' study isn't the only one to question the facial feedback theory. Recently, researchers cast doubt on one of the seminal studies in the field.

COLES: It was the first study that demonstrated that smiling could influence emotions, even if the participants were not aware that they were actually smiling.

SINGH: Seventeen labs across the globe failed to replicate the findings, and only one succeeded. And there's more bad news. It seems that in some cases, forced smiling can backfire. Another recent study found that service workers who were compelled to slap on a smile for customers were more likely to drink heavily after work.

Paula Niedenthal, a psychologist at the University of Wisconsin-Madison, wasn't involved in these recent studies. She says part of the problem may be that there are lots of different kinds of smiles.

PAULA NIEDENTHAL: There are multiple kinds of smiles, and they don't all relate to feelings of joy.

SINGH: Some smiles are sarcastic, more like smirks. Some smiles beam; others simper. And scientists are still trying to tease apart the relationship between genuine, joyful smiles and genuine joy. Until then, here's Coles' take.

COLES: I'm personally of the opinion that smiling is not going to make any important differences in your life.

SINGH: So for now, maybe hold back from telling people to turn their frowns upside down.

COLES: Because I know when I'm sad and people tell me to just smile through it, it just makes me more angry.

SINGH: For NPR News, I'm Maanvi Singh.