To get an unbiased estimate of how attractive the subjects were, the experimenters showed the photographs of all subjects to a separate panel of students and asked them to rate the subjects on a beauty scale, using standard procedures for normalizing the scores.

Armed with the data from these experiments and surveys, the economists found several interesting results. It turned out that beautiful people were no better than ordinary people in solving mazes. But despite having the same productivity as others in this task, beautiful people were a lot more confident about their own abilities. Being good looking seems to be strongly associated with self-confidence, a trait that is apparently attractive to employers.

When employers evaluated employees only on the basis of résumés, physical appearance had no impact on their estimates, as one would expect. But all of the other treatments showed higher productivity estimates for beautiful people, with the face-to-face interviews yielding the largest numbers.

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.

It seems that good-looking people are good communicators as well, and their oral communication skills contribute about as much to employers' perceptions as their looks.

As the researchers put it, "Employers (wrongly) expect good-looking workers to perform better than their less-attractive counterparts under both visual and oral interaction, even after controlling for individual worker characteristics and worker confidence."