I'm responding to the discussions I have been reading around the internets concerning judging competition winners by the way the finalists look. Everything seems to be based on this study.
I learned the hard way (during my periods of relatively unattractive adolescence and young adulthood), that looks really matter when you are trying to have people take you seriously as a musician. I was relatively clueless, and I had the clothes to prove it. My teacher, Julius Baker, even told me that I needed to do something to improve the way I looked, but I was simply not equipped to respond properly. To put it bluntly, I would have been an excellent candidate for What Not to Wear. Being a female flutist didn't help matters. I was surrounded by attractive young men and young women who knew how to dress. I knew how to practice, I knew how to grow myself intellectually and musically, and I knew how to make friends, but I did not know how to make my outside reflect the expressive parts of my insides. Being short but not, er, petite, never helped either.
Nothing is new here. Everyone who has a working pair of eyes would tell you that how a person looks when s/he is performing makes an impression. You can often tell something about the quality of a string player's sound by the way s/he draws the bow, and you can see personal involvement in any musician's face, as long as they don't have an instrument getting in the way. Consider the faces of oboists at work. Body language tells a lot as well, but body language tells a lot in any field of activity.
This study used samples of finalists from major international competitions in which all of the musicians could play their instruments at an extremely high level. In rare instances someone with a spectacular musical personality and original musicianship makes it into the finals, but more often people get to the final round of a music competition by either playing flawlessly, or make fewer mistakes than the other semi-finalists.
A competition is a truly subjective situation that is used by our culture as an objective measure of musicianship. Competition medals then become the currency for musical careers.
I doubt that any non-musician presented with a very short audio clip of three stellar musicians playing the same piece on the same instrument could be able to tell you the difference between the playing of each person. I know for certain that the same person could give details about how each person looked if given a video-only clip. If you can't tell the difference in the sound (and on recordings you really can't), the only basis on which to judge is the visual. Unfortunately many professional musicians would be guilty of the same kind of reaction.
I would take this study more seriously if there were controls concerning the piece of music the finalists played. The same piece might give a decent basis for comparison. I would also take it more seriously if the time involved was longer than six seconds, because we are all guilty of spending the first minute of watching any musical performance accustoming ourselves to the visual. It takes time to hear.
Also, the results of this study do not show that we can predict competition winners by the way they look, because the actual success rate (i.e. picking the winner) is just above 50%. I'm not able to do the math (you can thank my Juilliard education for that), but it seems to me that when you have three choices, and you choose one, you are bound to be right at least 30% of the time.