Economists have long known that attractive people get paid more than their more ordinary-looking colleagues. But why? A new experiment suggests an intriguing reason: It’s because employers expect beautiful people to accomplish more.

In the experiment, the researchers picked two groups of students: One would act as the “employers”, and one would act as the “applicants.” The employers were told they were going to interview applicants and pick the best ones for a job solving mazes.

The employers were given various levels of information about their prospective hires. In some cases, they were given only a resumé; in other cases, they were given a resumé and a photograph — or a resumé, photograph, and the ability to talk to the applicant on the phone. In other cases they got all of the above plus a face-to-face interview.

Then the employers had to pick which applicants they wanted to hire. By the way, the applicants had been tested for their maze-solving ability — and as you’d imagine, there was no correlation at all between their appearance and how good they were at solving mazes.

So who did the employers pick? Well, when they were allowed only to see the resumé — and had no idea what the person looked like or sounded like — physical appearance had no impact on the hiring. But in every other mode, the beautiful people did better.

Why? Because the employers thought that the attractive applicants were more likely to be highly productive than the others. Interestingly, the beautiful applicants themselves rated their own productivity highly; they were more confident. (The PDF of the paper is here if you want to read it yourself.)

The wildest thing, according to a story in today’s New York Times, is this:

Interestingly, employers thought beautiful people were more productive even when their only interaction was via a telephone interview. It appears that the confidence that beautiful people have in themselves comes across over the phone as well as in person.

But even when the experimenters controlled for self-confidence, they found that employers overestimated the productivity of beautiful people. The economists estimated that about 15 to 20 percent of the beauty premium is a result of the self-confidence effect, while oral and visual communication each contribute about 40 percent.

So this is what’s going on: Physical beauty produces a virtuous feedback loop. People constantly give you the sense that you’re better than everyone else, so you begin to believe it yourself — which just means that everyone is more likely to pick up on your radiant self-aura, and assess you even more highly. This, of course, falls squarely into the “yeah, I pretty much knew that already” camp of social-science research. But it’s always nice have new data confirming one’s grim opinion of humanity. It tracks nicely with recent findings that parents are more likely to be violent and neglectful with ugly children than with cute ones. Or the recent study finding that tall people make more than shorter ones — an extra $789 in annual pay per inch, in fact.

So the question is: Is it possible to hack one’s way into the cycle of positive self-assessment? If people who radiate confidence tend to be assessed more positively by employers, maybe it makes sense for everyone — not just obviously-attractive people — to barge into the job interview convinced that they’re god’s gift to humanity. Or does this ploy simply not work if you’re not actually hot? There are probably some strong gender determinants here: Most women rate “self confidence” as trait so desirable that it makes even troll-like men seem attractive; many men, on the hand, are freaked out by self-confident women.

It’s interesting how social science is finally generating some hard facts to quantify the social biases that second-wave feminists have long decried.