The Real Reason You Can't Always Control When You Smile

It's happened to us all. You're walking along the street and someone smiles at you. You smile back before you realize that you don't even know this person. Or maybe you're watching a scary movie and the villain cracks a smile. You smile back and then catch yourself wondering why you would smile at someone you don't even like.

And then there are times when nobody else around you is smiling. You're hurt or you're sad or you might even be so furious your hands are shaking, but you're still smiling. You know the smile might even be inappropriate depending on where you are, but you just can't help it. In these cases, smiling might just be your go-to response. According to BBC, researchers have identified 19 different types of smiles and only six of them are connected to positive feelings.

That doesn't explain the involuntary smiles, though. It's a behavior that baffles most people. But researchers have known for years that mimicking another person's facial expression is human nature. A study from 1982, upheld by more recent studies, found that people struggle to frown at a picture of a smiling person and vice versa (via Psychophysiology). Humans instinctively want to mimic the expressions of the people around them.

Although this first well-known study was published in 1982, researchers as recently as 2016 have been investigating this phenomena. They wanted to know why we smile when we see another person smiling, even if we know that smiling may not be an appropriate response.

This 2016 study, published in Trends in Cognitive Sciences, led researchers to the theory that the part of our brain in charge of facial recognition is also in charge of mimicry or the habit of mirroring. As soon as our brains process that we're looking at a human face, we process the expression on that face and seek to mimic it. The researchers behind the study theorize that it's a means of securing social safety. By mimicking those around us, we can fit more easily into any given situation even if we have no idea what's going on.

Practice and awareness makes it easier for us to avoid this gut reaction. But if you catch yourself smiling back at the bad guy on your favorite television show or scowling when you walk past a grumpy coworker's cubicle, it's not your fault. It's an instinctual reaction that you can blame on human evolution.