Maybe a number of us have had the experience of heading out for the night, feeling good, snapping a few selfies with your friends to memorialize for all time how great your hair is looking.
The next day, though, you're tagged in someone else's photos and… yikes.
How did you look so good in your photos and not in your friends?
Was that actually what you looked like all night?
Well, it could be the angle of the photo or the composition, or maybe your friend didn't get your left side, which we tend to think is our good side.
But it was probably related to exposure.
And I don't mean the exposure of the photo,
The mere exposure effect says that just becoming familiar with something makes us like it more.
For example, in one study of this phenomenon, researchers showed participants photos of men's faces, some of them repeatedly.
75% of the time, participants preferred faces they had seen before.
And when it comes to our own faces, we are more familiar with seeing them backwards.
Most of the time, we see our faces in the mirror, so what we see is reversed from other people and their cameras see.
The right side of your face looks like it's the left side, and vice versa.
And that matters because human faces are not perfectly symmetrical, which means we see our asymmetrical features on the wrong side of our face.
Maybe your crooked smile is higher on the right than on the left, or the corner of your left eye group instead of the right, and that birthmark, what you actually see on one cheek is now on the other.
Now, depending on the manufacturer of your phone, when you take a selfie, you're probably taking a picture as if your camera were a mirror.
In the final picture, everything is flipped so it looks exactly like what you'd expect to see after a lifetime of looking in the mirror.
When you look at a photo someone else took, you're looking at yourself the way the rest of the world sees you.
And those little asymmetries are enough to produce a slightly different face than you're used to.
That's why people tend to prefer reversed images of themselves over images from someone else's perspective; it's just more familiar.
In a 2015 study of female plastic surgery patients, 73% preferred looking at mirror-reversed photos of themselves.
But this is not a thing to worry about.
Just because you aren't used to it doesn't mean your friends think your un-flipped face is ugly.
In fact, since our friends have more exposure to seeing our faces the real way, they tend to prefer non-selfie photos of us.
Now, as it turns out, the mere exposure effect was way beyond selfies.