This suggests two solutions: Either make sure people don't see the candidates, an amazing but obviously impossible idea, or make sure people are educated—that they know what the candidates are about. That significantly reduces the biasing effect of facial competence.

Personality traits are also fraught, in that most studies rely on self-reported personality tests. "If I rate myself as extroverted and I try to look it in my pictures, you might rate me that way, but it doesn't mean I am." If there was some actual measure, like that when a person goes to parties, they make X number of friends, then we could start to talk about accuracy. But really, these studies just affirm that people see themselves the same way others see them.

(Trends in Cognitive Sciences, Olivola et al./The Atlantic)

In online dating, Olivola said, people are selecting pictures because they want to convey something. "You might think, 'Wow, this person looks really fun and outgoing.' Well, yeah, they're not going to post a picture of themselves where they're deep inside their books at the library. (Unless they're trying to attract a certain kind of person.) But if you ask an acquaintance, they may say, no, that person's not that fun. They think they are, but they're not."

All that these studies really tell us, Olivola said, is "'I've managed to fool you into thinking I'm extroverted, because that's how I like to be seen.' Of course I want everyone to think I'm intelligent and fun, and I like to think I am—"

"I'm sure you are," I said.

"So this is kind of dangerous," he continued after a beat. "I mean, is it wise for us to tell people, 'Oh, yeah, people are great at telling political orientation on the basis of faces.' If someone looks like they're conservative, or if they look like they're gay or whatever, it's totally okay for you to think you're probably right? We need to be more careful about that. It makes for great articles and everything, but when you look at the data critically, it paints a much less generous picture of the human ability to draw accurate inferences from faces. We need a lot of strong evidence before putting that message out there."

So this interesting research walks a thin line between relevant psychology and physiognomy. In the 1883 textbook Types of Insanity: An illustrated guide to the physical diagnosis of mental disease, Dr. Allan Hamilton wrote of a time when psychiatric practice was largely based on appearances. "When one walks through the wards of any asylum for the insane," Hamilton wrote, "he will be immediately impressed with the repulsiveness of the faces about him." The doctor includes characteristic sketches of people with melancholia, idiocy, imbecility, and mania—recognizable in a patient with "brows being corrugated, teeth covered by compressed lips, [and] eyes widely open."