I got 16 correct. My main method, as with others', was to watch for the expression before and after the smile, which really meant that I wasn't much looking at the smile at all, but attempting to work out whether they were forcing it or were being shown something to make them smile. It killed the challenge. I think it would have been much more difficult if the before and after smile parts of the videos were taken out, and perhaps then I'd only have managed to get around half correct. In the real world, I think it's much easier to tell if people are genuine or not, because you have context and other body language to read.
Very interesting though.
14 out or 20, but then again there are only 2 possible answers so a lot can simply be flukes

Man I must suck badly at this lol.
Okay... which is the fake smile:

<----->

LOL LOL LOL
15/20... next time when we fake our smiles, make sure to move the eyes too!
Why?! After the test it says: "Most people are surprisingly bad at spotting fake smiles. One possible explanation for this is that it may be easier for people to get along if they don't always know what others are really feeling. ...."
I scored 9 of the 20, only felt sure on a few of any of my answers. It's a rather awkward-looking test. I can only imagine how the people were instructed to smile, how a genuine smile was 'generated,' and it would seem to me that unless it was set up with them being instructed that the videos would be about something *other* than genuineness of the smile, they'd all (or nearly all) be fake to some extent. I'm tired & probably not explaining this well. Did that make sense at all?
Makes perfect sense to me.
I actually started writing something similar, but I felt it didn't make much sense, so instead of writing what I wanted to say, I wrote..:
I usually end up thinking to complicated, and destroy the test results with my own thoughts.

I got 15/20, I did two focusing on the eyes, how much the crinkled, and the cheeks. The rest, I focused on the throat, whether or not it did that little jump thing that happens when someone laughs, and then smiles.
Oh, just 13 out of 20. I found it strange that they all stopped smiling so suddenly and so quickly.
Really interesting quiz. I actually thought I would do better at it than I did. I got 12 out of 20.
What I mean by I thought I would do better is that in real life I am fairly good at spotting fake people, but I think I do that more by their tone of voice and the feeling that I get from them than how they are smiling.
Still I found the test hard. A few of the smiles came too fast and I just had to guess.
Results
You got 13 out of 20 correct
ooh dear!
gonna have to work on that then! 
Oh dear, 10 out of 20 for me, and that was very scary being stared at by 20 different people!
Its all in the eyes to tell. The way I see it though they are all fake afterall they are being told to smile

16 out of 20. That's pretty okay, but with some smiles I was like, 'was that the smile already? Did I miss something?'

Spot The Fake Smile
Results
You got 19 out of 20 correct
I'm NT
Spot The Fake Smile
Results
You got 16 out of 20 correct
I've spotted uncomfortable amounts of bogus smiles in classes dominated by pre-meds. I mean if a professor flipped his sausage on the table these pre-meds would fight over lipspace.. UNY if you know the place.