"Hey, all you artists out there! Since I have a face model I thought I'd take a crack at describing how some simple expression plays out on the face. How about a smile...that's pretty basic!"
"I mugged in the mirror for a while before writing this, and I'm already forgetting what I saw, so I better hurry up."
"OK, in the mirror I leaned back and registered surprise before smiling but I need to simplify things so I'll skip the lean. Here I just tried to look mildly surprised. You can see that all the features are flattened out. "
"My type of smile begins with the eyelids. They close softly and gently. It happens fast but if you could see it slowed down you'd be impressed by how innocent and tranquil the expression looks."
"Now the cheeks begin to dominate. They go up, out and in under the eye, describing (in the picture above) the letter "C" It's not symmetrical...one cheek usually gets a head start on the other. While all this is going on, the eyebrow begins to push the eyelash area farther down."
"This is the part I like the most. There comes a point when the scrinching eyes and cheek look like they've gone as far as they can go. It looks like the smile is over, but wait...."
"....it's not over at all! The eyebrow unexpectedly becomes dominant and violently forces a farther, deeper, more intense squinch. Even the cheeks are drawn into it. It fattens and wrinkles up the whole area around the eyes. But that's not all!
Toward the end of all this, before the face is completely wrinkled, the mouth suddenly springs to life. It had been busy traveling outward in order to help push the cheek upward, but now it asserts itself and makes a bid to dominate. It redoubles its effort, forcefully stretching the chin waaaay back and really far up before it settles to a red hot, smoking stop. When that ends, that's the end of the smiling mechanics. Fascinating, huh?
To summarize all this, what we have here is a quick fight for dominance. First the eye lids dominate, then the cheeks, then the eyebrows, then the mouth. It all happens very fast and a lot of it overlaps. I had to do this over and over before I could isolate the steps.
Of course, this is how I smile. Maybe you're different."
"Well, that's it! See ya next time on....'Science Corner!' "