The concept of facial feedback has been a standard in self-help for many years. According to its advocates, facial movement by itself can influence emotions.
You can be feeling as miserable as sin, and all you have to do is force yourself to smile and pretty soon you’ll be feeling on top of the world. Or vice versa, if you’re feeling happy and force yourself to frown.
In other words, “Fake it till you make it; sulk until you hulk. Act the way you want to feel, and the rest will fall into place. A frown can rev you up. Smiling can make you happy or decrease your stress.”
Indeed, a famous study conducted in 1988 by Fritz Strack, a Würzburg psychologist, was credited with having shown that “movements of the face lead to movements of the mind” and “proved that emotion doesn’t only go from the inside out but from the outside in.”
What Strack did was place a pen between the teeth of one group of subjects, forcing them to smile; and between the lips of a second group, forcing them to frown. The result was the group with the pen between their teeth scored higher on the “happiness scale” than the group with the pen between their lips.
Then it was decided to conduct a more comprehensive replication of the facial-feedback study.
The results came back — and they weren’t good anymore for the pro-smile advocators.
They showed that “the difference between the smilers and frowners had been reduced to three-hundredths of a rating point, a random blip, a distant echo in the noise.”