Can You Resist a Smile?

11/07/2012 05:09 pm ET | Updated Jan 07, 2013

"A smile is a curve that sets everything straight." -- Phyllis Dyer

Have you noticed that when you smile at someone, especially if you catch them off-guard, that they smile back?

OK, not everyone smiles back! Or do they?

I was telling a few friends about the exciting scientific research that shows how we are wired to smile back at others. Being determined to prove me wrong (I have nice friends!) they decided to test it out by just randomly smiling at people that morning.

One of my friends told me about her shopping trip to the local supermarket and how, after a few curious looks, people smiled back at her. It even led to a conversation with an elderly gentlemen and also a pleasant exchange at the cash register.

My other friend gave up after about half an hour because he hadn't been able to raise a smile from a single person. People either just looked straight through him or looked at him funnily.

It might have been the area that he lived in. Maybe people aren't too happy there. Or maybe it's because he's a man. That was his argument, anyway. But I assured him that even though people might not have visibly smiled back, they really did. They just didn't know that they did! That's when he looked at me funnily.

In the research, people were shown neutral faces on a computer screen (neither smiling nor frowning).... or so they thought. Actually, a happy face was flashed on the screen for about 30 milliseconds (thousandths of a second) before the neutral face appeared. It was so fast that the person wasn't consciously aware of it. But their brain saw it, and it reacted to it by pulling their smile muscle (the zygomaticus major muscle) into a superfast smile and relaxing it again in the blink of an eye.

The researchers measured this by fitting tiny electrodes to the facial muscles. The technique is called "facial EMG," and it can measure tiny movements of the muscles.

In another experiment, people were even shown happy faces and were instructed to frown as soon as they saw the faces. As expected, each person scowled as soon as they saw the happy faces. But they smiled first, even though they didn't know it. Facial EMG measured a superfast smile, again within a few thousandths of a second.

So I reassured my friend that everyone he smiled at that day really did smile back. They just didn't know that they smiled back.

And he smiled when I suggested that even if they don't visibly smile back at him, at least they'll be wondering what he's been up to.

For more by David R. Hamilton, Ph.D., click here.

For more on emotional intelligence, click here.