[pmoriarty]

The photographer stresses slightly raising one's lower eyelids (what he calls "squinching" -- a slight form of squinting), but if you notice, most of the examples he gives show people also slightly smiling more when they do this.

[TeMPOraL]

Today I learned that humans can control their lower eyelids. Now, I wonder how to learn to do that...

[slowmotiony]

It's a bit hard to describe but you gotta look at yourself in the mirror and just try it for a while. After a few moments your brain will figure it out. Took me around 15 minutes to get my lower eyelids to move, but now after some days of practicing I can even do it with a single eyelid only!

[AstralStorm]

Some work in front of the mirror. It is relatively easy.

There are muscles that are much harder to control, especially independently.

[acjohnson55]

My wife can't wink, or even close one eye independently. My eye muscles barely work together at all, so this is difficult for me to imagine!

[e12e]

To me this looks like the difference between "real" and "fake" smile (smiling with the eyes - or predator grin vs friendly smile). I have a friend who's a theathre actress - she smiles a lot wider than these models, but the eyes behave similarly.

Interesting video, thanks for sharing.